Manufacture and Modification of Tank Cars and Ton Containers for Transport of Dangerous Goods

8.1 General

8.1.1 Scope

The requirements set out in clauses 8.1 and 8.2 are general and basically apply to all tank cars and ton containers used in Canada for the handling, offering for transport, or transporting of dangerous goods. The requirements in clauses 8.3 to 8.6 apply to the design and manufacture of TC specification tank cars and ton containers. Specific requirements may have broader scope when referenced in other sections of this standard.

8.1.2 Responsibility of Manufacturer

The manufacturer of a tank car or ton container is responsible for obtaining approval of the Committee or Director, as applicable, for the design and manufacture of the tank car or ton container and for ensuring that the tank car or ton container conforms to all the applicable requirements of this standard.

8.1.3 Responsibility of Owner

The owner of a tank car or ton container is responsible for obtaining approval of the Committee or Director, as applicable, for the modification of the tank car or ton container and for ensuring that the tank car or ton container conforms to all the applicable requirements of this standard.

8.1.4 Marking and Certification

If this section requires a tank car or ton container to be marked with a TC Specification, the manufacturer of the tank car or ton container is responsible for ensuring compliance with that marking requirement.

8.2 General Technical and Safety System Requirements

8.2.1 Interior Heater Systems

8.2.1.1 Hydrostatic Test

Interior heater systems are authorized on Class 111 and 115 tank car tanks. Each interior heater system must be hydrostatically tested at the time of manufacture at not less than 13.8 bar (200 psi) and hold the pressure for 10 min without showing evidence of yielding or leakage. 

8.2.2 Minimum Burst Pressure 

The minimum burst pressure of a Class 111, a Class 115, or a pressure tank car tank must be the minimum burst pressure that corresponds to the tank test pressure set out in the following table:

Tank Test Pressure (TP) bar (psi)	Minimum Burst Pressure bar (psi)
4.14 (60)	16.6 (240)
6.90 (100)	34.5 (500)
TP ≥ 13.8 (200)	2.5 x TP

8.2.3 Protection for Service Equipment

8.2.3.1 Filling or Discharge Connections

If a tank car specification permits the location of filling or discharge connections in the bottom shell, the connections must be designed, manufactured and protected in accordance with paragraphs E9.0 and E10.0, of the AAR Specifications for Tank Cars publication.

8.2.3.2 Protective Housing

A Class 105, 112, 114, or 120 tank car must be equipped with a protective housing that conforms to the following requirements:

1. Except as provided in clause 8.3.23, a protective housing of cast, forged or fabricated materials must be bolted to the manway cover with not less than twenty 19 mm (¾ in.) nominal diameter studs or bolts;
2. The total ultimate shear strength of the studs or bolts attaching the protective housing to the manway cover must be equal to or less than 70% of the total ultimate shear strength of the studs or bolts attaching the manway cover to the manway nozzle;
3. The protective housing must have steel sidewalls equal to or greater than 19 mm (¾ in.) in thickness and must be equipped with a metal cover equal to or greater than 6 mm (¼ in.) in thickness that can be securely closed;
4. The protective housing cover must have a suitable stop to prevent the cover from striking the loading and unloading connections and must be hinged; and
5. Openings in the wall of the protective housing must be equipped with screw plugs or other closures.

8.2.4 Tank Car Capacity

A tank car manufactured after November 30, 1970 must not exceed, and existing tank cars must not be modified to exceed, a capacity of 130 582 L (34 500 US gallons).

8.2.5 Coupler Vertical Restraint System

8.2.5.1 Performance Standard

Each tank car must be equipped with couplers capable of sustaining, without disengagement or material failure, vertical loads equal to or greater than 90 718 kg (200 000 lb.) applied in upward and downward directions in combination with horizontal coupler compressive loads of 907 kg (2000 lb.), when coupled to railway vehicles which may or may not be equipped with couplers having this vertical restraint capability.

8.2.5.2 Test Verification

Except as provided in clause 8.2.5.4, compliance with the requirements of clause 8.2.5.1 must be verified by testing of a representative prototype of the coupler vertical restraint system in accordance with clause 8.2.5.3.

8.2.5.3 Coupler Vertical Restraint Test

A coupler vertical restraint system must be tested under the following conditions:

1. The test coupler must be tested with another coupler or simulated coupler having only frictional vertical force resistance at the mating interface; or having the capabilities described in clause 8.2.5.1;
2. The testing apparatus must simulate the vertical coupler performance at the mating interface and must not interfere with coupler failure or otherwise inhibit failure resulting from force applications and reactions; and
3. The test must be conducted as follows:
   1. A vertical downward load of not less than 90 718 kg (200 000 lb.) must be applied continuously for not less than 5 min to the test coupler head simultaneously with the application of a nominal horizontal coupler compressive load of 907 kg (2000 lb.);
   2. The procedures set out in the preceding clause must be repeated with a vertical upward load equal to or greater than 90 718 kg (200 000 lb.); and
   3. For each load combination specified in the two preceding clauses, not less than three consecutive successful tests must be performed. A test is successful if a vertical disengagement or material failure does not occur during the application of any of the loads specified in this clause.

8.2.5.4 Permitted Couplers

The following couplers are deemed to satisfy the testing requirements of clause 8.2.5.2:

1. E double shelf couplers designated by AAR Catalogue Nos. SE60CHT, SE60CC, SE60CHTE, SE60CE, SE60DC, SE60DE, SE67CC, SE67CE, SE67BHT, SE67BC, SE67BHTE, SE67BE, SE68BHT, SE68BC, SE68BHTE, SE68BE, SE69AHTE, and SE69AE; and
2. F double shelf couplers designated by the AAR Catalogue Nos. SF70CHT, SF70CC, SF70CHTE, SF70CE, SF73AC, SF73AE, SF73AHT, SF73AHTE, SF79CHT, SF79CC, SF79CHTE, and SF79CE.

8.2.6 Pressure-relief Devices

8.2.6.1 Performance Requirements

Except for ton containers, Class 113 and AAR 204W tank cars, tank car tanks must be equipped with one or more pressure-relief devices with sufficient flow capacity so that pressure buildup in the tank car tank, in fire conditions set out in Appendix A of the AAR Specifications for Tank Cars publication, does not exceed the flow rating pressure of the pressure-relief device.

8.2.6.2 Material

The pressure-relief device must be made of material compatible with the dangerous goods.

8.2.6.3 Settings for Reclosing Pressure-relief Devices

A reclosing pressure-relief device must have a start-to-discharge pressure:

1. equal to or greater than the WP;
2. equal to or less than 33% of the minimum tank car tank burst pressure; and
3. equal to or greater than 517 kPa (75 psi).

8.2.6.4 Flow Rating

The flow capacity and rating of pressure-relief devices must conform to the following requirements:

1. Each reclosing or non-reclosing pressure-relief device must conform to the requirements set out in Appendix A of the AAR Specifications for Tank Cars publication;
2. The manufacturer of a reclosing or non-reclosing pressure-relief device must verify conformity of any pressure-relief device to the requirement of Appendix A of the AAR Specifications for Tank Cars publication by testing a representative prototype of each pressure-relief device design; and
3. The flow rating pressure must be:
   1. for tank car tanks having a minimum burst pressure greater than 34.5 bar (500 psi), 110% of the start-to-discharge pressure; and
   2. for tank car tanks having a minimum burst pressure less than or equal to 34.5 bar (500 psi), not less than 110% and not greater than 130% of the start-to-discharge pressure.

8.2.6.5 Tolerances

Reclosing pressure-relief devices must conform to the following requirements:

1. The tolerance for the start-to-discharge pressure is ±21 kPa (±3 psi) for devices with a nominal start-to-discharge pressure equal to or less than 690 kPa (100 psi) and ±3% for devices with a nominal start-to-discharge pressure greater than 690 kPa (100 psi); and
2. The vapour-tight pressure must be equal to or greater than 80% of the start-to-discharge pressure.

8.2.6.6 Non-reclosing Pressure-relief Devices

A non-reclosing pressure-relief device must:

1. incorporate a rupture disc designed to burst at 33% of the tank car tank minimum burst pressure;
2. have an approach channel and a discharge channel that do not reduce the minimum flow capacity of the pressure-relief device;
3. be designed to not be interchangeable with other fittings installed on the tank car;
4. have a structure that encloses and clamps the rupture disc in position in order to prevent, when properly applied, any distortion or damage to the rupture disc; and
5. have a cover designed to direct any discharge of the dangerous goods downward and with a means of preventing misplacement.

8.2.6.7 Rupture Disc

A rupture disc must:

1. be compatible with the dangerous goods;
2. be manufactured in accordance with the requirements set out in Appendix A of the AAR Specifications for Tank Cars publication;
3. not have an opening; and
4. have an actual burst pressure within +0 to -15% of the burst pressure marked on the disc.

8.2.6.8 Pressure-relief devices in combination

1. If a non-reclosing pressure-relief device is used in series with a reclosing pressure-relief device, the reclosing pressure-relief device must be located outboard of the non-reclosing pressure-relief device;
2. If a breaking pin device is used in combination with a reclosing pressure-relief device, the breaking pin device must be designed to fail at the pressure set out in clause 8.2.6.3, and the reclosing pressure-relief device must be set to start discharging at a pressure no greater than 95% of that pressure;
3. If a rupture disc is used in combination with a reclosing pressure-relief device:
   1. the rupture disc must be designed to burst at the pressure set out in clause 8.2.6.3;
   2. the reclosing pressure-relief device must be set to start to discharge at a pressure no greater than 95% of the pressure set out in clause 8.2.6.3;
   3. a needle valve, trycock, or telltale indicator must be installed to allow detection of any accumulation of pressure between the rupture disc and the reclosing pressure-relief device; and
   4. the vapour-tight pressure and the tolerance of the start-to-discharge pressure of the reclosing pressure-relief device must be based on the discharge setting of that device.

8.2.6.9 Location of Pressure-relief Devices

A pressure-relief device must communicate with the vapour space above the dangerous goods and be located as near as practicable on the longitudinal centreline and centre of the tank.

8.2.6.10 Marking of Pressure-relief Devices

A pressure-relief device must be permanently marked in accordance with the requirements set out in Appendix A of the AAR Specifications for Tank Cars publication.

8.2.7 Thermal Protection Systems

8.2.7.1 Performance Standard

If a thermal protection system is specified by this standard, the system must be capable of preventing the release of any dangerous goods from a tank car filled to its authorized loading limit, except release through the pressure-relief device, when subjected to the following conditions:

1. A pool-fire for 100 min; and
2. A torch-fire for 30 min.

8.2.7.2 System Survivability and Thermal Analysis

Compliance with the requirements set out in clause 8.2.7.1 must be verified first by testing the system for survivability in accordance with Appendix D and be verified then by analyzing the behaviour of the tank car and dangerous goods when subjected to fire conditions set out in clause 8.2.7.1, and such analysis must take into account the following parameters acting in combination:

1. the fire effects on and heat flux through tank discontinuities, protective housings, underframes, metal jackets, insulation, and thermal protection;
2. an upright and a 120° roll over orientation along the longitudinal axis of the tank car;
3. a pool-fire which completely engulfs the tank car with fire temperatures equal to or greater than 815.5°C (1500°F) and a torch-fire temperature equal to or greater than 1204.4°C (2200°F);
4. tank external surface emissivity being equal to or greater than 0.9;
5. a discharge coefficient of the pressure-relief device of 0.8 for vapour and 0.6 for liquids or the use of other values, provided the use of such other values is supported by actual test data;
6. the heat transfer properties of the thermal protection or insulation material as a function of temperature, as established by actual test data;
7. the dangerous goods being at an initial temperature of 46°C (115°F) or the highest lower temperature at which the dangerous goods can exist in the liquid state within the tank;
8. the maximum volumetric filling limit specified for the dangerous goods excluding any modified filling limit applicable during winter; and
9. the composition and thermal properties of the dangerous goods.

8.2.7.3 Record retention

A complete record of each analysis must be made and retained by the owner of the tank car.

8.2.8 Tank-head Puncture-resistance Systems

8.2.8.1 Performance Standard

If a tank-head puncture-resistance system is specified, it must be capable of sustaining the coupler to tank-head impacts specified in Appendix C, at relative tank car speeds of 29 km/h (18 mph) without any loss of dangerous goods when:

1. the mass of the impacting car is equal to or greater than 119 295 kg (263 000 lb.);
2. the impacted tank car is coupled to one or more stationary backup cars that have a total mass equal to or greater than 217 724 kg (480 000 lb.) and the hand brake is applied on the last backup car; and
3. the internal pressure of the impacted tank car is equal to or greater than 6.9 bar (100 psi).

8.2.8.2 Verification

Conformance with the requirements of clause 8.2.8.1, must be verified by full-scale testing in accordance with Appendix C or, as an alternative, compliance with the requirements of clause 8.2.8.1, is considered to be achieved by installing a full-head protection shield or a full tank-head jacket on each end of the tank car that conforms to the following requirements:

1. The shield or jacket must be equal to or greater than 12.7 mm (0.5 in.) in thickness, shaped to the contour of the tank-head and made from steel that has a minimum specified tensile strength equal to or greater than 380 MPa (55 000 psi);
2. The design and test requirements of the shield or jacket must conform to the impact test requirements set out in par. 5.3, of the AAR Specifications for Tank Cars publication; and
3. The workmanship for the shield or jacket must conform to the requirements set out in Chapter 5 of the AAR Design, Fabrication, and Construction of Freight Cars publication.

8.2.8.3 Deeming Provision

Unless otherwise specified in this standard, a Class 105 tank car that has a tank test pressure equal to or greater than 34.5 bar (500 psi) is deemed to conform to the tank-head puncture-resistance system requirements of clause 8.2.8.

8.3 General Requirements Applicable to TC Class 111 Tank Car Tanks and TC Pressure Tank car Tanks

8.3.1 General

A TC Specification 111 or a TC pressure tank car tank must conform to the requirements set out in this clause, except where otherwise provided by the individual specification.

8.3.2 Pressure Tank Car Tanks

A pressure tank car tank must:

1. be fusion welded with formed convex outward heads;
2. be circular in cross section;
3. be provided with a manway nozzle on top;
4. have a manway cover where all valves, measuring devices and sampling devices are mounted;
5. have a protective housing conforming to clause 8.2.3.2;
6. not have openings in the tank; and
7. have normalized shell and heads when made from carbon steel. Heads must be normalized after forming unless the Committee specifically approved otherwise.

8.3.3 TC Specification 111 Tank Car Tanks

A TC Specification 111 tank car tank must:

1. be fusion welded with formed convex outward heads;
2. be circular in cross section; and
3. have at least one manway.

8.3.4 Welding

Welders must comply with and welding procedures must conform to the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.3.5 Metal Plate

8.3.5.1 

Carbon and low alloy steel plate used must conform with Appendix M of the AAR Specifications for Tank Cars publication.

8.3.5.2 Aluminum Alloy Plate:

1. alloys must be used in one of the following tempers: 0, H112, or H32, except for alloy 5083 which must be used in the 0 temper only;
2. filler material alloy conforming to Unified Numbering System UNS A95556 must not be used; and
3. the plate must conform to one of the specifications and corresponding minimum tensile strength, set out in the following table:

   Specification	Minimum Tensile Strength MPa (psi)
   ASTM B209M or B209, Alloy 5052	170 (25 000)
   ASTM B209M or B209, Alloy 5083	265 (38 000)
   ASTM B209M or B209, Alloy 5086	240 (35 000)
   ASTM B209M or B209, Alloy 5154	205 (30 000)
   ASTM B209M or B209, Alloy 5254	205 (30 000)
   ASTM B209M or B209, Alloy 5454	215 (31 000)
   ASTM B209M or B209, Alloy 5652	170 (25 000)

8.3.5.3 High Alloy Steel Plate:

1. the plate must conform to one of the specifications and corresponding minimum tensile strength set out in the following table; and

   Specification	Minimum Tensile Strength MPa (psi)
   ASTM A240/A240M, Type 304L	485  (70 000)
   ASTM A240/A240M, Type 316L	485  (70 000)

2. the plate must be tested in accordance with the procedure indicated for the plate material and, after sensitizing treatment, must exhibit a corrosion rate in testing no greater than the corresponding value indicated in the Test and Maximum Corrosion Rate table:

        Test and Maximum Corrosion Rate

   ASTM A262 Test Procedure	Material	Corrosion Rate mm (in.) per month
   Practice B	Types 304L and 316L	0.1016 (0.0040)
   Practice C	Type 304L	0.0508 (0.0020)

8.3.6 Minimum Thickness

8.3.6.1 

The minimum thickness, in millimetres (inches), after forming of the tank shell and of 2:1 ellipsoidal heads must be the greater of:

1. the minimum plate thickness specified in clauses 8.3.22 or 8.3.24; or

2. the plate thickness calculated using the following formula:

    

   
    

   where:

   t = minimum thickness of plate, in mm (in.), after forming

   P = minimum burst pressure, in bar (psi)

   d = inside diameter, in cm (in.)

   S = minimum tensile strength of plate material, in MPa (psi), as specified in clause 8.3.5

   E = 0.9, a factor representing the efficiency of welded joints, except that for welds that are 100% radiographed, E = 1.0

8.3.6.2

If cladding material having minimum tensile strength properties equal to or greater than the base plate is used, the cladding may be considered to be a part of the base plate when determining thickness. However, if cladding material that has lower tensile strength is used, the base plate alone must conform to the thickness requirement.

8.3.7 Tank Heads

8.3.7.1

External tank heads must have the form of an ellipsoid of revolution in which the major axis is equal to the diameter of the shell and the minor axis is equal to one half the major axis.

8.3.7.2

Internal compartment tank heads on a Specification 111 tank car tank must either have the form of a 2:1 ellipsoid or be flanged and dished to a thickness, as set out in clause 8.3.6. A flanged and dished internal head must have:

1. a main inside radius equal to or less than 3 m (10 ft.); and
2. an inside knuckle radius equal to or greater than:
   1. 9.5 cm (3¾ in.) for steel, alloy steel, or nickel tanks; and
   2. 12.7 cm (5 in.) for aluminum alloy tanks.

8.3.7.3

Subject to clause 8.3.7.4 each tank head made from steel which is required to be "fine grain" or "fine grain practice" by the material specification and which is hot-formed at a temperature equal to or greater than 926.7°C (1700°F) must be normalized after forming by heating the steel to a temperature between 843.3°C and 926.7°C (1550°F and 1700°F), holding at that temperature for the greater of 30 min or a minimum of 1 h per 25 mm (1 in.) of thickness, and cooling in air.

8.3.7.4

If the material specification requires quenching and tempering, the treatment requirements set out in that specification must be used instead of the one set out in clause 8.3.7.3.

8.3.8 Compartmented Specification 111 Tank Car Tanks

8.3.8.1 

If a tank is divided into compartments by inserting internal heads:

1. the internal heads must be inserted in conformance with the requirements set out in par. E7.0, of the AAR Specifications for Tank Cars publication, and must conform to the requirements specified in clause 8.3.24;
2. voids between compartment heads must be provided with at least one tapped drain hole at their lowest point and a tapped hole at the top of the tank and the tapped holes must not be less than ¾ NPT and not greater than 1½ NPT in size; and
3. the top and bottom holes must be closed with solid NPT plugs.

8.3.8.2 

If a tank is divided into compartments by manufacturing each compartment as a separate tank:

1. the separate tanks must be joined together by a cylinder made of plate having a thickness equal to or greater than that required for the tank shell;
2. the cylinder must
   1. be applied to the outside surface of the tank head flanges;
   2. fit the straight flange portion of the compartment tank head tightly;
   3. contact the head flange for a distance of at least two times the plate thickness or a minimum of 25 mm (1 in.), whichever is the greater; and
   4. the cylinder must be joined to the head flange by a full fillet weld.
3. the distance from head seam to cylinder must be equal to or greater than 38 mm (1½ in.) or three times the plate thickness, whichever is the greater;
4. voids created by the space between heads of tanks joined together to form a compartment tank must be provided with a tapped drain hole at their lowest point and a tapped hole at the top of the tank and the tapped holes must not be less than ¾ NPT and not greater than 1½ NPT in size; and
5. the top and bottom holes must be closed with solid NPT plugs.

8.3.9 Attachments

8.3.9.1 

A tank manufactured after November 1971 must have reinforcing pads between external brackets and tank if the attachment welds to tank are equal to or greater than 150 linear mm (6 linear in.) of 6 mm (¼ in.) fillet or equivalent weld per bracket or bracket leg. Reinforcing pads are not required for the following attachments:

1. thin attachments, such as exterior heater coils and drip ledges;
2. cast bottom outlet skids that are attached to tanks over a broad area;
3. full-girth attachments, such as compartmented tank attachment rings and tank stiffening rings, that are continuously attached to tanks; or
4. tank bottom reinforcing plates or bars and attachments welded thereto.

8.3.9.2 

Regardless of date manufactured, reinforcing pads are required for:

1. any air brake equipment support attachments; and
2. any other bracket or attachment, regardless of weld length, if they could cause damage to the tank either through fatigue, over-stressing, denting or puncturing in the event of an accident.

8.3.9.3 

Reinforcing pads must:

1. be equal to or greater than 6 mm (¼ in.) in thickness;
2. not exceed the thickness of the tank shell to which they are welded, by more than 15%;
3. have each corner rounded to a radius equal to or greater than 25 mm (1 in.);
4. be attached to the tank by continuous fillet welds, except for venting provisions; and
5. a pad-to-tank fillet weld leg size not exceeding the tank shell thickness.

8.3.9.4 

The distance between a bracket and the edge of the reinforcing pad to which it is attached must not be less than three times the thickness of the pad.

8.3.9.5 

The ultimate shear strength of the bracket to reinforcing pad weld must be equal to or less than 85% of the ultimate shear strength of the reinforcing pad to tank weld.

8.3.10 Bottom Outlets

8.3.10.1 

The bottom outlet must not extend from the tank shell more than that authorized in Appendix E of the AAR Specifications for Tank Cars publication.

8.3.10.2 

Each bottom outlet reducer and closure and their attachments must be secured by, at least, a 10 mm (3/8 in.) chain or its equivalent, except that outlet closure plugs may be secured by a 7 mm (¼ in.) chain;

8.3.10.3 

If the bottom outlet closure is of the combination cap-and-valve type, the pipe connection to the valve must be closed by a plug, cap, or quick-coupling device.

8.3.10.4 

The bottom outlet must include only the valve, reducer, and closures that are necessary for the attachment to unloading equipment.

8.3.10.5 

Each bottom outlet must be provided with a liquid tight closure at its lower end.

8.3.10.6 

On tank cars with continuous centre sills, a ball valve may be welded to the outside bottom of the tank or mounted on a pad or nozzle that is attached to the outside bottom of the tank using a tongue-and-groove or male-and-female flange attachment. The breakage groove or its equivalent must not extend below the bottom flange of the centre sill.

8.3.10.7 

On tank cars without continuous centre sills, a ball valve may be welded to the outside bottom of the tank or mounted on a pad using a tongue-and-groove or male-and-female flange attachment. The pad must be attached to the outside bottom of the tank.

8.3.10.8 

The pad referred to in clauses 8.3.10.6 and 8.3.10.7, must have a maximum thickness of 64 mm (2½ in.) measured on the longitudinal centreline of the tank.

8.3.10.9 

The valve operating mechanism must include a means of locking the valve in the closed position during transport.

8.3.10.10 

To provide for the attachment of unloading connections, the bottom of the main portion of the outlet nozzle or valve body of exterior valves, or any fixed attachment thereto, must be provided with:

1. a bolted flange closure arrangement including a 1 in. NPT pipe plug or including an auxiliary valve with a threaded closure;
2. a threaded cap closure arrangement including a 1 in. NPT pipe plug or including an auxiliary valve with a threaded closure;
3. a quick-coupling device that has a threaded plug closure equal to or greater than 1 NPT or has a threaded cap closure with a 1 in. NPT pipe plug. A minimum 1 in. nominal size auxiliary test valve with a threaded closure may be substituted for the 1 in. NPT pipe plug. If the threaded cap closure does not have a pipe plug or integral auxiliary test valve, a 1 in. NPT pipe plug must be installed in the outlet nozzle above the closure; or
4. a two-piece quick-coupling device using a clamped dust cap must include an in-line auxiliary valve either integral with the quick-coupling device or located between the primary bottom outlet valve and the quick-coupling device. The quick-coupling device closure dust cap or outlet nozzle must be fitted with a 1 in. NPT closure.

8.3.10.11 

If the outlet nozzle extends 152 mm (6 in.) or more from the shell of the tank, the outlet nozzle must conform to the following requirements:

1. A breakage "V" groove must be cut, not cast, into the upper part of the outlet nozzle at a point immediately below the lowest part of the valve to a depth that leaves the thickness of the nozzle wall at the root of the "V" equal to or less than 6 mm (¼ in.);
2. If the outlet nozzle on interior valves or the valve body on exterior valves is steam-jacketed, the breakage groove or its equivalent must be below the steam chamber but above the bottom of the centre sill for tank cars with continuous center sills;
3. If the outlet nozzle is not a single piece or if exterior valves are applied, provision must be made for the equivalent of the breakage groove;
4. On tank cars without continuous centre sills, the breakage groove or its equivalent must be equal to or less than 381 mm (15 in.) below the tank shell; and
5. On tank cars with continuous centre sills, the breakage groove or its equivalent must be above the bottom of the centre sill.

8.3.10.12 

The thickness of the flange on the outlet nozzle or the valve body of exterior valves must be sufficient to:

1. prevent distortion of the valve or valve seat by any change in contour of the shell resulting from the expansion of the dangerous goods or from the expansion due to other causes; and
2. ensure that accidental breakage of the outlet nozzle will occur at or below the breakage "V" groove or its equivalent.

8.3.10.13 

The valve must have no wings or stem projecting below the breakage "V" groove or its equivalent. The valve and valve seat must be readily accessible or removable for repairs, including grinding.

8.3.11 Bottom Washouts

8.3.11.1 

The bottom washout must not extend from the tank shell more than that authorized in Appendix E of the AAR Specifications for Tank Cars publication.

8.3.11.2 

If the washout nozzle extends 152 mm (6 in.) or more from the tank shell, the washout nozzle must conform to the following requirements:

1. A breakage "V" groove must be cut, not cast, in the upper part of the washout nozzle at a point immediately below the lowest part of the inside closure seat or plug to a depth that leaves the thickness of the nozzle wall at the root of the "V" equal to or less than 6 mm (¼ in.);
2. If the washout nozzle is not a single piece, provision must be made for the equivalent of the breakage groove;
3. The thickness of the washout nozzle must be sufficient to ensure that accidental breakage will occur at or below the breakage "V" groove or its equivalent;
4. On tank cars without continuous centre sills, the breakage "V" groove or its equivalent must be equal to or less than 381 mm (15 in.) below the tank shell; and
5. On tank cars with continuous centre sills, the breakage "V" groove or its equivalent must be above the bottom of the centre sill.

8.3.11.3 

The closure of the washout nozzle must be equipped with a ¾ in. NPT solid plug. The plug must be attached to its nozzle by, at least, a 7 mm (¼ in.) chain.

8.3.12 Manway Nozzles and Covers on a TC Pressure Tank Car Tank

8.3.12.1 

A manway nozzle must be manufactured of forged or rolled steel for steel tanks or of aluminum alloy for aluminum tanks and must have an access opening with an inside diameter equal to or greater than 457 mm (18 in.) or at least 356 X 457 mm (14 X 18 in.) obround or oval. The nozzle must be welded to the tank and the opening reinforced in conformance with the requirements set out in Appendix E of the AAR Specifications for Tank Cars publication.

8.3.12.2 

The manway cover must be attached to the manway nozzle by bolts or studs not entering the tank.

8.3.13 Manway Flanges, Safety Device Flanges, Bottom Outlet Nozzle Flanges, Bottom Washout Nozzle Flanges, and Other Attachments and Openings on a Specification 111 Tank Car Tank

8.3.13.1 

The attachments must be fusion-welded to the tank and reinforced in conformance with the requirements set out in Appendix E of the AAR Specifications for Tank Cars publication.

8.3.13.2 

The opening in the manway must have a diameter equal to or greater than 406 mm (16 in.), except that lined manways must have a diameter equal to or greater than 457 mm (18 in.) before lining.

8.3.13.3 

The manway flange must be made of cast, forged, or fabricated metal that is weldable to the metal of the tank shell.

8.3.13.4 

Openings for manways or for other service equipment must be reinforced.

8.3.14 Post-weld Heat Treatment

8.3.14.1 

After welding is completed, steel tanks and all attachments welded thereto must be post-weld heat-treated as a unit in conformance with the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.3.14.2 

For aluminum tanks, post-weld heat treatment is prohibited.

8.3.14.3 

Tanks and welded attachments fabricated from high alloy steel materials do not require post-weld heat treatment.

8.3.15 Manway Covers on a Specification 111 Tank Car Tank 

Manway covers must conform to the requirements set out in par. E4.3 of the AAR Specifications for Tank Cars publication.

8.3.16 Venting Valves, Loading and Unloading Valves, Gauging, Measuring, and Sampling Devices on a TC Pressure Tank Car Tank

8.3.16.1 

The venting valves and loading and unloading valves must be made of metal compatible with the dangerous goods and must withstand the tank test pressure without leakage.

8.3.16.2 

The venting valves and loading and unloading valves must be bolted directly to seatings on the manway cover, except as provided in clause 8.3.23.

8.3.16.3 

The outlets of venting valves and loading and unloading valves must be closed with screw plugs or other closures fastened to prevent misplacement.

8.3.16.4 

The interior pipes of the loading and unloading valves must be anchored.

8.3.16.5 

Gauging devices, sampling devices, and thermometer wells must:

1. be made of metal compatible with the dangerous goods and withstand the tank test pressure without leakage;
2. the interior pipe of the thermometer well must be anchored in a manner to prevent breakage; and
3. the thermometer well must be closed by a valve attached near the manway cover and closed by a screw plug. Other arrangements that permit testing the thermometer well for leaks without complete removal of the closure may be used.

8.3.16.6 

A sump or siphon bowl, welded or pressed into the shell, must conform to the following requirements:

1. The sump or siphon bowl must be made of cast, forged, or fabricated metal that is weldable to the metal of the tank shell;
2. If the sump or siphon bowl is pressed into the bottom of the tank shell, the wall thickness of the pressed section must be equal to or greater than that specified for the shell;
3. The section of a tank of circular cross section to which the sump or siphon bowl is attached need not conform to the out-of-roundness requirement set out in par. W14.6 of the AAR Specifications for Tank Cars publication; and
4. Any portion of the sump or siphon bowl not forming a part of a cylinder of revolution must have walls of such thickness and be so reinforced that the stresses in the walls caused by internal pressure are equal to or less than the circumferential stress caused by the same internal pressure in the wall of a tank of circular cross section designed in conformance with the requirements set out in clause 8.3.6. The wall thickness must be equal to or greater than that specified in clause 8.3.22.

8.3.17 Gauging Devices, Top Loading and Unloading Devices, Venting, and Air Inlet Devices for a Specification 111 Tank Car Tank

8.3.17.1 

Each device must be of a design that will prevent interchange with any other service equipment.

8.3.17.2 

Unloading pipes must be securely anchored within the tank.

8.3.17.3 

When the device is equipped with valves or fittings to permit the loading and unloading, each device, including valves or fittings, must be provided with a protective housing.

8.3.17.4 

Protective housings are not required when plug or ball-type valves are used and their operating handles are removed.

8.3.17.5 

Provision must be made for closing the pipe connections of valves.

8.3.17.6 

A protective housing is not required for a vacuum-relief valve.

8.3.17.7 

When a tank car with a hinged manway cover is equipped with a fixed internal gauging bar an outage indicator visible through the manway opening must be provided.

8.3.17.8 

If loading devices are applied to permit tank loading with the cover closed, a telltale pipe may be used. The telltale pipe must be capable of indicating that the required outage is provided. The pipe must be equipped with a control valve equal to or less than ¼ NPT mounted outside the tank and enclosed within a protective housing.

8.3.17.9 

Other devices may be used instead of the outage indicator or telltale pipe referred to in clauses 8.3.17.7 or 8.3.17.8.

8.3.17.10 

A sump or siphon bowl, welded or pressed into the shell, must conform to the following requirements:

1. The sump or siphon bowl must be made of cast, forged, or fabricated metal that is weldable to the metal of the tank shell;
2. If the sump or siphon bowl is pressed into the bottom of the tank shell, the wall thickness of the pressed section must be equal to or greater than that specified for the shell;
3. The section of a tank of circular cross section to which the sump or siphon bowl is attached need not conform to the out-of-roundness requirement set out in par. W14.6 of the AAR Specifications for Tank Cars publication; and
4. Any portion of the sump or siphon bowl not forming a part of a cylinder of revolution must have walls of such thickness and be so reinforced that the stresses in the walls caused by internal pressure are equal to or less than the circumferential stress caused by the same internal pressure in the wall of a tank of circular cross-section designed in conformance with the requirements set out in clause 8.3.6. The wall thickness must be equal to or greater than that specified in clause 8.3.24.

8.3.17.11 

If top loading,discharge, venting or air inlet devices are installed at a location remote from the manway and with exposed piping:

1. shut-off valves must be applied directly to reinforcing pads or nozzles at their communication through the tank shell and must be enclosed in a protective housing with provision for a seal;
2. the piping must include breakage grooves and suitable bracing;
3. relief valves must be applied to liquid lines for protection in case dangerous goods are trapped; and
4. provision must be made to ensure closure of the shut-off valves during transport.

8.3.17.12 

Protective housing, if required, must have a cover and sidewalls no less than 3.0 mm (0.119 in.) in thickness.

8.3.18 Plugs for Openings

8.3.18.1 

Each plug must be solid, with NPT threads, and must be of a length that will screw at least six threads inside the face of the fitting or tank.

8.3.18.2 

Each plug, if inserted from the outside of a Specification 111A tank head, must have the letter "S" equal to or greater than 10 mm (3/8 in.) in height stamped or cast on the outside surface. The letter "S" indicates that the plug is solid.

8.3.19 Insulation

Specification 105, 111A100W3 and 120 tank cars require insulation. When insulation is required, the insulation must conform to the following requirements:

1. The tank shell, head and manway nozzle must be insulated;
2. The insulation must be covered with a metal jacket that has a thickness equal to or greater than 3.0 mm (0.119 in.) and must be flashed around all openings so as to be weathertight;
3. The exterior surface of a carbon steel tank and the inside surface of a carbon steel jacket must be given a coating to protect against corrosion;
4. If exterior heaters are attached to the tank, the thickness of the insulation over each heater element may be reduced to one half that required for the shell; and
5. The insulation must be of sufficient thickness so that the overall thermal conductance at 15.6°C (60°F) is equal to or less than 1.533 kJ/h m² °C (0.075 Btu/h ft.² °F).

8.3.20 Permanent Markings

Subject to clause 7.3 a tank car tank must conform to the following marking requirements:

8.3.20.1 

Each tank must have permanent markings, including:

1. tank car tank specification;
2. month and year of the original tank test;
3. tank manufacturer's identifying mark;
4. tank car assembler's identifying mark, if different from the tank manufacturer; and
5. material specification of the tank wall, including separate material specifications for the shell and heads if they are different and the cladding material specification if the tank is internally clad.

8.3.20.2 

The permanent markings must be stamped in letters and figures equal to or greater than 10 mm (3/8 in.) in height into the metal on the external surface and near the centre of both heads.

8.3.20.3 

In the case of a TC Specification 111 tank car tank, the last numeral of the Specification number may be omitted from the marking; for example, a "TC 111A100W" marking for a specification 111A100W2 tank car. The following is an example of the required markings:

8.3.21 Pressure Testing of Tanks

8.3.21.1 

Each tank must be tested by:

1. completely filling the tank and manway nozzle with water or other liquid having similar viscosity, at a temperature equal to or less than 37.8°C (100°F) during the test; and
2. applying a pressure equal to or greater than the tank car tank test pressure for at least 10 minutes.

8.3.21.2 

Tanks must be tested before insulation is applied.

8.3.21.3 

Tanks must be tested before any lining or coating is applied.

8.3.21.4 

Repairs must be made in conformance with the requirements set out in Appendix R of the AAR Specifications for Tank Cars publication.

8.3.21.5 

Testing of exterior heaters is not required.

8.3.21.6 

For a successful pressure test there must be no evidence of tank yielding or leakage during the 10 minutes hold period.

8.3.22 Additional Requirements for TC Pressure Tank Car Tank Specifications

The requirements of column 2 to 7 of this table apply to the corresponding specification indicated in the first column:

     Individual Specification Requirements

TC Specification	Minimum Plate Thickness  =mm (in.)	Tank Test Pressure bar (psi)	Minimum Manway Cover Thickness mm (in.)	Bottom Outlet	Bottom Washout	Specific Requirement
105A100ALW	15.9 (5/8)	6.9 (100)	63.5 (2½)	No	No	8.3.22.1
105A200ALW	15.9 (5/8)	13.8 (200)	63.5 (2½)	No	No	8.3.22.1
105A300ALW	15.9 (5/8)	20.7 (300)	66.7 (2 5/8)	No	No	8.3.22.1
105A100W	14.3 (9/16)	6.9 (100)	57.2 (2¼)	No	No	8.3.22.2
105A200W	14.3 (9/16)	13.8 (200)	57.2 (2¼)	No	No	8.3.22.2
105A300W	17.5 (11/16)	20.7 (300)	57.2 (2¼)	No	No	8.3.22.2 8.3.22.3 8.3.22.4
105A400W	17.5 (11/16)	27.6 (400)	57.2 (2¼)	No	No	8.3.22.2 8.3.22.3 8.3.22.4
105A500W	17.5 (11/16)	34.5 (500)	57.2 (2¼)	No	No	8.3.22.2 8.3.22.3
105A600W	17.5 (11/16)	41.4 (600)	57.2 (2¼)	No	No	8.3.22.2 8.3.22.3
112A200W	14.3 (9/16)	13.8 (200)	57.2 (2¼)	No	No	8.3.22.2 8.3.22.5
112A340W	17.5 (11/16)	23.4 (340)	57.2 (2¼)	No	No	8.3.22.2 8.3.22.3
112A400W	17.5 (11/16)	27.6 (400)	57.2 (2¼)	No	No	8.3.22.2 8.3.22.3
112A500W	17.5 (11/16)	34.5 (500)	57.2 (2¼)	No	No	8.3.22.2 8.3.22.3
114A340W	17.5 (11/16)	23.4 (340)		Optional	Optional	8.3.22.2 8.3.22.3 8.3.22.6
114A400W	17.5 (11/16)	27.6 (400)		Optional	Optional	8.3.22.2 8.3.22.3 8.3.22.6
120A200ALW	15.9 5/8	13.8 (200)	63.5 (2½)	Optional	Optional	8.3.22.1
120A100W	14.3 (9/16)	6.9 (100)	57.2 (2¼)	Optional	Optional	8.3.22.2
120A200W	14.3 (9/16)	13.8 (200)	57.2 (2¼)	Optional	Optional	8.3.22.2
120A300W	17.5 (11/16)	20.7 (300)	57.2 (2¼)	Optional	Optional	8.3.22.2 8.3.22.3
120A400W	17.5 (11/16)	27.6 (400)	57.2 (2¼)	Optional	Optional	8.3.22.2 8.3.22.3
120A500W	17.5 (11/16)	34.5 (500)	57.2 (2¼)	Optional	Optional	8.3.22.2 8.3.22.3

8.3.22.1 

If material other than aluminum alloys are used, the thickness must be equal to or greater than 57 mm (2¼ in.).

8.3.22.2 

The steel of the shell and heads must be in the normalized condition.

8.3.22.3 

If steel of 485 to 560 MPa (70 000 to 81 000 psi) minimum tensile strength is used, the plate thickness must be equal to or greater than 16 mm (5/8 in.) and, if steel of 560 MPa (81 000 psi) minimum tensile strength is used, the plate thickness must be equal to or greater than 14 mm (9/16 in.).

8.3.22.4 

If the characteristics of the dangerous goods require the use of nickel or nickel alloy, the thickness must be equal to or greater than 50 mm (2 in.).

8.3.22.5 

For a tank car tank having an inside diameter equal to or less than 221 cm (87 in.), the plate thickness must be equal to or greater than 13 mm (½ in.).

8.3.22.6 

The requirements set out in clause 8.3.23.2 and par. E4.1 of the AAR Specifications for Tank Cars publication apply.

8.3.23 Additional Requirements for TC Specification 114 and 120 Pressure Tank Car Tanks

8.3.23.1 Service equipment and openings

Service equipment need not be mounted on the manway cover and one opening may be provided in each head for use in purging the tank interior.

8.3.23.2 Manway Cover

A protective housing is not required if no service equipment is mounted on the manway cover.

8.3.23.3 Venting Valves, Loading and Unloading Valves, and Measuring and Sampling Devices

Venting valves, loading and unloading valves, and measuring and sampling devices must conform to the following requirements:

1. if used, they must be attached to a nozzle or nozzles on the tank shell or heads;
2. they must be grouped in one location and, except as provided in clause 8.3.12, must be equipped with a protective housing with cover or must be recessed into the tank shell with cover. An additional set of venting valves, loading and unloading valves, and measuring and sampling devices grouped in another location is permitted;
3. the protective housing with cover, if used, must have steel sidewalls of a thickness equal to or greater than 19 mm (3/4 in.) and a metal cover that can be securely closed and has a thickness equal to or greater than 6 mm (¼ in.); and
4. for service equipment recessed into the tank shell with cover, the cover must be made of metal having a thickness equal to or greater than 6 mm (1/4 in.).

8.3.23.4 Pressure-relief Devices and Pressure Regulators 

Pressure-relief devices and pressure regulators must conform to both of the following requirements:

1. they must be located on top of the tank near the centre of the car on a nozzle, mounting plate, or recessed in the shell. Any bolt or stud, if used, must not enter the tank; and
2. metal guards must be provided to protect pressure-relief devices and pressure regulators from damage.

8.3.24 Additional Requirements for TC 111 Tank Car Tank Specifications 

The requirements of column 2 to 6 of this table apply to the corresponding specification indicated in the first column:

     Individual Specification Requirements

TC Specification	Minimum Plate Thickness mm (in.)	Tank Test Pressure bar (psi)	Bottom Outlet	Bottom Washout	Specific Requirement
111A60ALW1	12.5 (1/2)	4.14 (60)	Optional	Optional	8.3.27.1
111A60ALW2	12.5 (1/2)	4.14 (60)	No	Optional	—
111A100ALW1	15.8 (5/8)	6.9 (100)	Optional	Optional	8.3.27.1
111A100ALW2	15.8 (5/8)	6.9 (100)	No	Optional	—
111A100W1	11.1 (7/16)	6.9 (100)	Optional	Optional	8.3.27.1
111A100W2	11.1 (7/16)	6.9 (100)	No	Optional	—
111A100W3	11.1 (7/16)	6.9 (100)	Optional	Optional	8.3.27.1 8.3.19
111A100W5	11.1 (7/16)	6.9 (100)	No	No	8.3.25 8.3.27.2
111A100W6	11.1 (7/16)	6.9 (100)	Optional	Optional	8.3.26 8.3.27.1 8.3.27.3
111A100W7	11.1 (7/16)	6.9 (100)	No	No	8.3.25 8.3.27.3

8.3.24.1 TC Specification 111 Suffixes

A TC Specification 111 tank car tank listed in the table of clause 8.3.24 must conform to the following requirements:

1. An "ALW" TC Specification tank car tank must be manufactured from aluminum alloy plate;
2. A "W1" through "W5" TC Specification tank car tank must be manufactured from carbon steel plate;
3. A "W6" and "W7" TC Specification tank car tank must be manufactured from high alloy steel plate; and
4. A "W5" TC Specification tank car tank must have an interior lining that conforms to the requirements set out in clause 8.3.25.

8.3.25 Lined Tanks

8.3.25.1 Rubber lined Tanks:

1. A tank or each compartment of a tank must be lined with acid resistant rubber or other rubber compound vulcanized or bonded directly to the metal tank to provide a non-porous laminated lining. The thickness of the lining must be equal to or greater than 4 mm (5/32 in.);
2. The rubber lining must:
   1. overlap at least 38 mm (1½ in.) at all edges and the edges must be straight and beveled to an angle of approximately 45° or, if the edges of the rubber lining are butted, the butted edges must be sealed with a minimum 76 mm (3 in.) strip of lining having 45° beveled edges; or
   2. be joined with a skived butt seam and then capped with a separate strip of lining having a width of 76 mm (3 in.) and having 45° beveled edges. If this method is used;
      1. an additional rubber reinforcing pad having an area equal to or greater than 0.4 m2 (4½ ft.2) and a thickness equal to or greater than 13 mm (½ in.) must be applied by vulcanizing the rubber reinforcing pad to the lining on the bottom of the tank directly under the manway opening;
      2. the edges of the rubber reinforcing pad must be beveled at an angle of approximately 45°;
      3. an opening in the rubber reinforcing pad for sump is permitted;
      4. no part of the lining or pad must be under tension when applied; and
      5. the interior of the tank must be free from scale, oxidation, moisture, and all foreign matter during the lining operation.
3. Before a tank car tank is lined with an acid-resistant rubber or other rubber compound, a report certifying that the tank and its equipment are in compliance with TC Specification 111A100W5 must be furnished by the tank car owner to the party who is to apply the lining. A copy of this report, certifying that the tank has been lined in conformance with all requirements of TC Specification 111A100W5, must be furnished by the party lining the tank to the tank car owner. The tank car owner must retain reports of the latest lining application until the next relining has been accomplished and recorded.

8.3.25.2 Tanks Lined with Other Materials

Other lining materials may be used provided the material is compatible with the dangerous goods and is suitable for the service temperatures.

8.3.25.3 Other Related Requirements

1. A tank car tank or each compartment of a tank car tank may be lined with elastomeric polyvinyl-chloride having a lining thickness equal to or greater than 2.3 mm (3/32 in.);
2. A tank car tank or each compartment of a tank car tank may be lined with elastomeric polyurethane having a lining thickness equal to or greater than 1.6 mm (1/16 in.);
3. Hard rubber or polyvinyl chloride may be used for the pressure-retaining parts of safety vents provided the material is compatible with the dangerous goods and is suitable for the service temperatures;
4. All surfaces of attachments or service equipment and their closures that are exposed to the dangerous goods must be covered with acid-resistant material having a thickness equal to or greater than 3 mm (1/8 in.). Attachments made of metal that are not affected by the dangerous goods need not be covered with rubber or other acid-resistant material.

8.3.26 Material

All service equipment, tubes, castings, and all projections and their closures, but not protective housings, must conform to the requirements specified in ASTM A262, except that when preparing the specimen for testing, the carburized surface may be finished by grinding or machining.

8.3.27 Manways and Manway Closures

8.3.27.1 

The manway cover must be designed to make it impossible to remove the cover while the interior of the tank is under pressure.

8.3.27.2 

In the case of a TC Specification 111A100W5 tank car tank:

1. the manway cover must be made of metal;
2. the bottom of the manway cover must be lined with an acid-resistant material applied in accordance with the requirements set out in clause 8.3.25 unless it is made of metal that is compatible with the dangerous goods; and
3. through bolt holes must be lined with acid-resistant material having a thickness equal to or greater than 3 mm (1/8 in.).

8.3.27.3 

The manway flange and cover must conform to the requirements set out in par. M3.3 of the AAR Specifications for Tank Cars publication.

8.4 General Requirements Applicable to TC Class 115 Tank Car Tanks Consisting of an Inner Container Supported Within an Outer Shell

8.4.1 General

TC Specification 115 tank car tanks must conform to the requirements set out in this clause, except where otherwise provided by the individual specification.

8.4.2 TC Specification 115 Tank Car Tanks

TC Specification 115 tank car tanks must consist of an inner container, a support system for the inner container, and an outer shell.

8.4.3 Inner Container and Outer Shell

8.4.3.1

The inner container must:

1. be a fusion-welded tank of circular cross section with formed convex outward heads; and
2. have a manway on top of the tank conforming to the requirements set out in this section.

8.4.3.2

If the inner container is divided into compartments, each compartment is considered to be a separate container.

8.4.3.3

The outer shell must be a fusion-welded tank with formed convex outward heads.

8.4.4 Insulation

The annular space between the inner container and the outer shell must contain insulation material. The insulation material must be of sufficient thickness so that the overall thermal conductance at 15.6°C (60°F) is equal to or less than 0.777 kJ/h m² °C (0.038 Btu/h ft.² °F).

8.4.5 Minimum Thickness

8.4.5.1

The minimum thickness, in millimetres (inches), after forming of the inner container shell and of 2:1 ellipsoidal heads must be the greater of:

1. the minimum plate thickness specified in clause 8.4.23.1; or

2. the plate thickness calculated using the following formula:

    

   
    

   where:

   t = minimum thickness of plate, in mm (in.), after forming

   P = minimum burst pressure, in bar (psi)

   d = inside diameter, in cm (in.)

   S = minimum tensile strength of plate material, in MPa (psi), as specified in clause 8.4.6

   E = 0.9, a factor representing the efficiency of welded joints, except that for welds that are 100% radiographed, E = 1.0

8.4.5.2

The minimum thickness, in millimetres (inches), after forming of the inner container heads, if the heads are flanged and dished, must be the greater of:

1. the minimum plate thickness specified in clause 8.4.23.1; or

2. the plate thickness calculated using the following formula:

    

   
    

   where:

   t = minimum thickness of plate, in mm (in.), after forming

   P = minimum burst pressure, in bar (psi)

   L = main inside radius to which the head is dished, measured on the concave side, in cm (in.)

   S = minimum tensile strength of plate material, in MPa (psi), as specified in clause 8.4.6

   E = 0.9, a factor representing the efficiency of welded joints, except that for welds that are 100% radiographed, E = 1.0

8.4.5.3

The wall thickness, after forming, of the cylindrical section and heads of the outer shell must be equal to or greater than 11 mm (7/16 in.).

8.4.5.4

If the inner container is divided into compartments, the thickness must conform to the requirements specified in clauses 8.4.9 and 8.4.10.

8.4.6 Metal Plate for Inner Container and Nozzles

8.4.6.1 Carbon and Low Alloy Steel Plate:

1. must conform to one of the following specifications and grades: ASTM A516/A516M, Grade 70/485 or AAR TC128, Grade B;
2. must have a maximum carbon content of 0.31%; and
3. may be clad with other materials authorized in Appendix M of the AAR Specifications for Tank Cars publication.

8.4.6.2 Aluminum Alloy Plate:

1. must be used in one of the following tempers: 0, H112, or H32, except for alloy 5083 that must be used in the 0 temper only;
2. filler material alloy conforming to unified Numbering System UNS A95556 must not be used; and
3. the plate must conform to one of the specifications and corresponding minimum tensile strength set out in the following table:

Specification	Minimum Tensile Strength MPa  (psi)
ASTM B209M or B209, Alloy 5052	170 (25 000)
ASTM B209M or B209, Alloy 5083	265 (38 000)
ASTM B209M or B209, Alloy 5086	240 (35 000)
ASTM B209M or B209, Alloy 5154	205 (30 000)
ASTM B209M or B209, Alloy 5254	205 (30 000)
ASTM B209M or B209, Alloy 5454	215 (31 000)
ASTM B209M or B209, Alloy 5652	170 (25 000)

8.4.6.3 High Alloy Steel Plate

In the case of high alloy steel plate, the plate must conform to one of the following specifications and types: ASTM A240/A240M Type 304, 304L, 316, or 316L.

8.4.6.4 Manganese molybdenum Steel Plate

In the case of manganese-molybdenum steel plate, the manganese-molybdenum steel plate must conform to specification ASTM A302/A302M, Grade B.

8.4.7 Metal Plate for Outer Shell

8.4.7.1

The cylindrical section and heads of the outer shell must be manufactured from the materials listed in clause 8.4.6, and, in the case of steel plate materials, listed in clauses 8.4.6.1, 8.4.6.3, or 8.4.6.4;

1. The maximum carbon content is 0.31%; and
2. The steel plate may be clad with other materials authorized in Appendix M of the AAR Specifications for Tank Cars publication.

8.4.8 Material for Service Equipment

All service equipment on the inner container in contact with the dangerous goods must be made with materials that are compatible with the plate material of the inner container and be compatible with the dangerous goods or must be coated or lined with suitable corrosion-resistant material. Materials for castings and fittings must conform to the requirements set out in par. M4.5 of the AAR Specifications for Tank Cars publication.

8.4.9 Tank Heads

8.4.9.1

Heads of the inner container, the compartments of the inner container, and the outer shell must be flanged and dished or have the form of an ellipsoid and must be convex outward.

8.4.9.2

Ellipsoidal heads must be an ellipsoid of revolution in which the major axis is equal to the diameter of the shell and the minor axis is equal to one-half the major axis.

8.4.9.3

Flanged and dished heads must have:

1. a main inside radius equal to or less than 3 m (10 ft.); and
2. an inside knuckle radius equal to or greater than:
   1. 9.5 cm (3¾ in.) for steel and alloy steel tanks; and
   2. 12.7 cm (5 in.) for aluminum alloy tanks.

8.4.10 Compartmented Tanks

8.4.10.1

The inner container may be divided into compartments by:

1. inserting interior heads;
2. manufacturing each compartment as a separate container and joining the compartments with a cylinder; or
3. manufacturing each compartment as a separate tank without joining the compartments with a cylinder.

8.4.10.2

Each compartment must be capable of withstanding, without evidence of yielding or leakage, the required tank test pressure applied in each compartment separately or in any combination of compartments.

8.4.10.3

If the inner container is divided into compartments by manufacturing each compartment as a separate container and joining the compartments with a cylinder:

1. the cylinder must have a plate thickness equal to or greater than that required for the inner container shell;
2. the cylinder must be applied to the outside surface of the straight flange portion of the container head;
3. the cylinder must fit the straight flange tightly for a distance of at least two times the plate thickness or 25 mm (1 in.), whichever is greater;
4. the cylinder must be joined to the straight flange by a full fillet weld; and
5. the distance from fillet weld seam to container head seam must be equal to or greater than 38 mm (1½ in.) or three times the plate thickness, whichever is greater.

8.4.11 Welding

8.4.11.1

Welders must comply with and welding procedures must conform to the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.4.11.2

Radiography of the outer shell is not a specification requirement.

8.4.12 Post-weld Heat Treatment

8.4.12.1

Post-weld heat treatment of the inner container is not required.

8.4.12.2

Post-weld heat treatment of the cylindrical portions of the outer shell to which the anchorage or draft sills are attached must conform to the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.4.12.3

If cold-formed heads are used on the outer shell and post-weld heat treatment is not practicable due to assembly procedures, the cold-formed heads must be heat-treated before welding to the cylindrical section of the outer shell.

8.4.13 Inner Container Manway Nozzle and Cover

8.4.13.1

A manway nozzle must be designed with an access opening having an inside diameter equal to or greater than 457 mm (18 in.) or at least 356 x 457 mm (14 x 18 in.) obround or oval.

8.4.13.2

The design of the manway nozzle and its cover must ensure a secure closure and must prevent the removal of the cover while the tank interior is under pressure.

8.4.13.3

All joints between manway covers and their seats must be made vapour-tight and liquid-tight by the use of suitable gaskets.

8.4.13.4

Manway covers must be of cast, forged, or fabricated metal and must conform to the requirements of clause 8.4.8.

8.4.13.5

A seal must be provided between the manway nozzle of the inner container and the opening in the outer shell.

8.4.14 Opening in the Tanks

Openings in the inner container and the outer shell must be reinforced in conformance with Appendix E of the AAR Specifications for Tank Cars publication. In calculating the required reinforcement area for openings in the outer shell, "t" must be equal to 6 mm (¼ in.).

8.4.15 Support System for Inner Container

8.4.15.1

The inner container must be supported within the outer shell by a support system of such strength and ductility that, at the operating temperature of the support system, the system is capable of supporting the inner container when filled with liquid dangerous goods to any level.

8.4.15.2

The support system must be designed to support, without yielding, impact loads producing accelerations of the following magnitudes and directions when:

1. the inner container is loaded so that the tank car is at its rail load limit; and
2. the tank car is equipped with a conventional AAR Specification M-901 draft gear:
   1. Longitudinal 7g
   2. Transverse 3g
   3. Vertical 3g

8.4.15.3

The longitudinal acceleration may be reduced to 3g if a cushioning device, which has been tested to demonstrate its ability to limit tank car tank forces to a maximum of 1779 kN (400 000 lb.) at an impact speed of 16 km/h (10 mph), is used between the coupler and the tank structure.

8.4.15.4

The inner container must be thermally isolated from the outer shell to the maximum practical extent.

8.4.15.5

The inner container and outer shell must be electrically bonded to each other, either by the support system used, by piping, or by a separate electrical connection.

8.4.16 Gauging Devices, Top Loading and Unloading Devices, Venting and Air Inlet Devices

8.4.16.1

Each device must be designed to prevent interchange with any other service equipment.

8.4.16.2

Each pipe must be securely anchored within the inner container.

8.4.16.3

Each inner container or compartment of an inner container may be equipped with one separate air connection.

8.4.16.4

If the dangerous goods are such that a device must be equipped with valves or fittings to permit the loading and unloading of the dangerous goods, each device, including valves or fittings, must be enclosed within a protective housing.

8.4.16.5

Protective housings are not required when plug or ball-type valves are used and their operating handles are removed.

8.4.16.6

Provision must be made for closing the pipe connections of valves.

8.4.16.7

An inner container may be equipped with a vacuum-relief valve and, if an inner container is so equipped, a protective housing is not required.

8.4.16.8

When a gauging device is required, an outage indicator visible through the manway opening must be provided.

8.4.16.9

If loading devices are applied to permit tank loading with the cover closed, a telltale pipe may be used. The telltale pipe must be capable of indicating that the required outage is provided. The pipe must be equipped with a control valve equal to or less than ¼ in. NPT mounted outside the tank and enclosed within a protective housing.

8.4.16.10

Other devices may be used instead of the outage indicator or a telltale pipe referred to in clauses 8.4.16.8 or 8.4.16.9.

8.4.16.11

A sump or siphon bowl, welded or pressed into the shell, must conform to the following requirements:

1. The sump or siphon bowl must be made of cast, forged, or fabricated metal that is weldable to the metal of the tank shell;
2. If the sump or siphon bowl is pressed into the bottom of the inner container shell, the wall thickness of the pressed section must be equal to or greater than that specified for the shell;
3. The section of a tank of circular cross section to which the sump or siphon bowl is attached need not conform to the out-of-roundness requirement set out in par. W14.6 of the AAR Specifications for Tank Cars publication; and
4. Any portion of the sump or siphon bowl not forming a part of a cylinder of revolution must have walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are equal to or less than the circumferential stress that would exist under the same internal pressure in the wall of a tank of circular cross section designed in conformance with the requirements set out in clauses 8.4.5.1 and 8.4.10 The wall thickness must be equal to or greater than that specified in clause 8.4.23.1.

8.4.16.12

Protective housing, if required, must have a cover and sidewalls having a thickness equal to or greater than 3.0 mm (0.119 in.).

8.4.17 Bottom Outlets and Outer Shell Openings

8.4.17.1

The bottom outlet must not extend from the outer shell more than that authorized in Appendix E of the AAR Specifications for Tank Cars publication.

8.4.17.2

Each bottom outlet reducer and closure and their attachments must be secured to the tank car by, at least, a 10 mm (3/8 in.) chain or its equivalent, except that outlet closure plugs may be secured by a 7 mm (¼ in.) chain.

8.4.17.3

If the bottom outlet closure is of the combination cap-and-valve type, the pipe connection to the valve must be closed by a plug, cap, or quick-coupling device.

8.4.17.4

The bottom outlet equipment must include only the valve, reducer, and closures that are necessary for the attachment to unloading equipment.

8.4.17.5

Each bottom outlet must be provided with a liquid-tight closure at its lower end.

8.4.17.6

The valve and its operating mechanism must be applied to the outside bottom of the inner container and the valve operating mechanism must include a means of locking the valve in the closed position during transport.

8.4.17.7

To provide for the attachment of unloading connections, the bottom of the main portion of the outlet nozzle or valve body, or any fixed attachment thereto, must be provided with a threaded cap closure arrangement or bolted flange closure arrangement having a maximum 1 in. NPT solid plug.

8.4.17.8

If the outlet nozzle and its closure extend below the bottom of the outer shell, the outlet nozzle must conform to the following requirements:

1. A breakage "V" groove or its equivalent must be cut, not cast, into the upper part of the outlet nozzle at a point immediately below the lowest part of the valve to a depth that leaves the thickness of the nozzle wall at the root of the "V" equal to or less than 6 mm (¼ in.);
2. If the outlet nozzle on interior valves or the valve body on exterior valves is steam-jacketed, the breakage groove or its equivalent must be below the steam chamber but above the bottom of the centre sill for tank cars with continuous center sills;
3. If the outlet nozzle is not a single piece or if exterior valves are applied, provision must be made for the equivalent of the breakage groove;
4. On tank cars without continuous centre sills, the breakage groove or its equivalent must be equal to or less than 381 mm (15 in.) below the outer shell; and
5. On tank cars with continuous centre sills, the breakage groove or its equivalent must be above the bottom of the centre sill.

8.4.17.9

The thickness of the valve body must be such that it is capable of:

1. preventing distortion of the valve or valve seat by any change in contour of the inner container shell resulting from the expansion of the dangerous goods or from other causes; and
2. ensuring that accidental breakage of the outlet nozzle will occur at or below the breakage "V" groove or its equivalent.

8.4.17.10

The valve must have no wings or stem projecting below the breakage "V" groove or its equivalent. The valve and valve seat must be readily accessible or removable for repairs, including grinding;

8.4.18 Bottom Washouts

8.4.18.1

The bottom washout equipment must not extend from the outer shell more than that authorized in Appendix E of the AAR Specifications for Tank Cars publication.

8.4.18.2

If the washout nozzle extends below the bottom of the outer shell, the washout nozzle must conform to the following requirements:

1. A breakage "V" groove must be cut, not cast, in the upper part of the washout nozzle at a point immediately below the lowest part of the inside closure seat or plug to a depth that leaves the thickness of the nozzle wall at the root of the "V" equal to or less than 6 mm (¼ in.);
2. If the washout nozzle is not a single piece, provision must be made for the equivalent of the breakage groove;
3. The thickness of the washout nozzle must be sufficient to ensure that accidental breakage will occur at or below the breakage "V" groove or its equivalent;
4. On tank cars without continuous centre sills, the breakage "V" groove or its equivalent must be equal to or less than 381 mm (15 in.) below the outer shell; and
5. On tank cars with continuous centre sills, the breakage "V" groove or its equivalent must be above the bottom of the centre sill.

8.4.18.3

The closure plug and seat must be readily accessible or removable for repairs, including grinding.

8.4.18.4

The closure of the washout nozzle must be equipped with a ¾ in. NPT solid plug. The plug must be attached to its nozzle by, at least, a 7 mm (¼ in.) chain.

8.4.18.5

Joints between closures and their seats must be gasketed with suitable material.

8.4.19 Plugs for Openings

8.4.19.1

Each plug must be solid, with NPT threads, and must be of a length that will screw at least six threads inside the face of the fitting or tank.

8.4.19.2

Each plug, if inserted from the outside of the outer shell tank heads, must have the letter "S" equal to or greater than 10 mm (3/8 in.) in height stamped with a steel stamp or cast on the outside surface. The letter "S" indicates that the plug is solid.

8.4.20 Pressure Testing of the Inner Container

8.4.20.1

Each inner container or compartment must be tested hydrostatically to a pressure equal to or greater than the specification test pressure.

8.4.20.2

The temperature of the pressurizing medium must be equal to or less than 37.8°C (100°F) during the test.

8.4.20.3

The inner container must hold the specified pressure for at least 10 min without evidence of yielding or leakage.

8.4.20.4 

Pressure-relief devices must be removed during the test.

8.4.20.5 

The inner container must be pressure-tested before installation within the outer shell.

8.4.20.6

Items that, because of assembly sequence, must be welded to the inner container after its installation within the outer shell must have their attachment welds thoroughly inspected by a non destructive evaluation method conforming to Appendix T of the AAR Specifications for Tank Cars publication

8.4.21 Permanent Markings

Subject to clause 7.3 the marking on a Specification 115 tank car tank must conform to the following requirements:

8.4.21.1

Each outer shell must have permanent markings, including:

1. tank car tank specification;
2. month and year of the original pressure test of the inner container;
3. inner container manufacturer's identifying mark;
4. material specification of the inner container;
5. as-built thickness of the shell and heads of the inner container;
6. material specification of the outer shell;
7. outer shell manufacturer's identifying mark; and
8. tank assembler's identifying mark, if different from the inner container or outer shell manufacturer; and

8.4.21.2

The permanent markings must be stamped in letters and figures equal to or greater than 10 mm (3/8 in.) in height into the metal near the centre of both outside heads. The inner container heads must not be stamped. The following is an example of the required markings.

8.4.22 Stencilling

8.4.22.1

The outer shell must be stencilled in conformance with the requirements set out in Appendix C of the AAR Specifications for Tank Cars publication.

8.4.22.2

The safe upper temperature limit, if applicable, for the inner tank, insulation and support system must be applied by stencilling on both sides of the outer shell near the centre in letters and figures equal to or greater than 38 mm (1½ in.) in height.

8.4.23 Individual Specification Requirements Applicable to TC Specification 115 Tank Car Tanks

8.4.23.1 Individual Specification Requirements

In addition to the applicable requirements set out in clause 8.4.1, the inner container must conform to the individual specification requirements corresponding to the TC Specification set out in the following table:

     Individual Specification Requirements

TC Specification	Minimum Inner Container Thickness mm (in.)	Test Pressure bar (psi)	Bottom Outlet	Bottom Washout
115A60ALW	4.8 (3/16)	4.14 (60)	Optional	Optional
115A60W1	3 (1/8)	4.14 (60)	Optional	Optional
115A60W6	3 (1/8)	4.14 (60)	Optional	Optional

8.5 General Requirement Applicable to TC Class 106A and TC Class 110A Ton Containers

8.5.1 General

A TC Specification 106A and TC Specification 110A ton container must conform to the requirements set out in this section and any other applicable requirements set out in this standard.

8.5.2 TC Specification 106A and 110A ton containers

Each ton container must be cylindrical and circular in cross section. All openings must be located in the head. Each ton container must have a water capacity of at least 679.5 kg (1500 lb.) and not more than 1177.8 kg (2600 lb.).

8.5.3 Insulation

Insulation is prohibited.

8.5.4 Burst Pressure

The minimum burst pressure must conform to the requirements specified in clause 8.5.19.

8.5.5 Minimum Shell Thickness

The shell thickness must conform to the following requirements:

8.5.5.1

For a Specification 110A ton container, the shell thickness of the cylindrical portion, must be the greater of:

1. the minimum thickness of shell specified in clause 8.5.19; or

2. the shell thickness calculated using the following formula:

    

   
    

   where:

   t = minimum thickness of shell, in mm (in.), after forming

   P = minimum burst pressure, in bar (psi)

   d = inside diameter, in cm (in.)

   S = minimum tensile strength of plate material, in MPa (psi), as specified in clause 8.5.6

   E = 1.0, a factor representing the efficiency of welded joints

8.5.5.2

For a Specification 106A ton container, the shell thickness of the cylindrical portion must be equal to or greater than that specified in clause 8.5.19 and must be such that, at the tank test pressure, the maximum fibre stress in the tank shell is equal to or less than 108.6 MPa (15 750 psi) as calculated using the following formula:

 

where:

s = shell stress, in MPa (psi)

P = tank test pressure, in MPa (psi)

D = outside diameter, in cm (in.)

d = inside diameter, in cm (in.)

8.5.5.3

If cladding material having a lower tensile strength is used, the thickness of the cladding shall not be included in the calculation of minimum shell thickness.

8.5.6 Metal Plate

8.5.6.1

The maximum carbon content for carbon and low alloy steel plate is 0.31%.

8.5.6.2

All plates must have their heat number and the name or brand of the manufacturer legibly stamped on them at the rolling mill.

8.5.6.3

The steel plates must conform to one of the specifications and corresponding minimum tensile strength set out in the following table:

Specification	Minimum Tensile Strength MPa (psi)
ASTM A240/A240M, Type 304	515 (75 000)
ASTM A240/A240M, Type 304L	485 (70 000)
ASTM A240/A240M, Type 316	515 (75 000)
ASTM A240/A240M, Type 316L	485 (70 000)
ASTM A240/A240M, Type 321	515 (75 000)
ASTM A285/A285M, Grade A	310 (45 000)
ASTM A285/A285M, Grade B	345 (50 000)
ASTM A285/A285M, Grade C	380 (55 000)
ASTM A515/A515M, Grade 65/450	450 (65 000)
ASTM A515/A515M, Grade 70/485	485 (70 000)
ASTM A516/A516M, Grade 70/485	485 (70 000)

8.5.7 Tank Heads

8.5.7.1

For a Specification 110A ton container:

1. the tank must have fusion welded heads, formed concave outward;
2. the heads must be 2:1 ellipsoidal with the major axis equal to the diameter of the shell and the minor axis equal to one-half the major axis;
3. the heads must be one piece and hot-formed so as to provide a straight flange having a length equal to or greater than 38 mm (1½ in.); and

4. the head thickness must be equal to or greater than that calculated by the following formula:

    

   
    

   where symbols are as defined in clause 8.5.5.1.

8.5.7.2

For a Specification 106A ton container,

1. the tank must have forge welded heads, formed convex outward;
2. heads must be of torispherical form with an inside radius equal to or less than the inside diameter of the shell;
3. heads must be one piece and hot-formed so as to provide a straight flange having a length equal to or greater than 102 mm (4 in.);
4. heads must be drive fit into the shell for forge welding; and
5. the wall thickness of the heads, after forming, must conform to the test requirements set out in clause 8.5.5.2 and provide for adequate threading of openings.

8.5.8 Welding

8.5.8.1

Welders must comply with and welding procedures must conform to the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.5.8.2

Longitudinal joints in the shell must be fusion-welded.

8.5.8.3

Fusion welded joints must conform to the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication, except that circumferential welds in tanks having an inside diameter less than 914 mm (36 in.) need not be radiographed.

8.5.8.4

Forge welded joints must be hot-hammered or hot-rolled to ensure sound welds and:

1. the flanges of the heads must be forge lap welded to the shell and then crimped inwardly toward the centreline at least 25 mm (1 in.) on the radius; and
2. welding and crimping must be accomplished in one heat cycle.

8.5.9 Post-weld Heat Treatment

After welding is complete a carbon steel ton container and all its welded attachments must be post-weld heat-treated as a unit in conformance with the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.5.10 Protection of Service Equipment

8.5.10.1

Ton containers must be designed to provide protection to any service equipment or attachment to the head, including the detachable protective housing referred to in clause 8.5.10.2. Tank ends must slope or curve inward toward the axis so that the diameter at each end is at least 50 mm (2 in.) less than the maximum diameter.

8.5.10.2

Loading and unloading valves must be protected by a detachable housing which must not project beyond the end of the tank and must be securely fastened to the tank head. The detachable protective housing must not cover any pressure-relief devices of the ton container.

8.5.11 Venting, Loading, and Unloading Valves

8.5.11.1

Valves must be made of metal that is compatible with the dangerous goods and must withstand tank test pressure without leakage.

8.5.11.2

Valves must be screwed directly into or attached to one of the tank heads.

8.5.11.3

The outlet connections of the valves must be closed.

8.5.11.4

Threads for openings must be NGT tapped to gauge, clean cut, even, and without checks.

8.5.12 Attachments Not Otherwise Specified

Siphon pipes and their couplings on the inside of the tank heads and lugs on the outside of the tank heads for attaching the valve protective housing must be fusion welded in place prior to post-weld heat treatment.

8.5.13 Pressure-relief Devices

8.5.13.1

Unless otherwise prohibited in this standard, a tank must be equipped with one or more pressure-relief devices made of metal that is compatible with the dangerous goods and that are screwed directly into the tank heads.

8.5.13.2

The total discharge capacity of a pressure-relief device must be sufficient to prevent a build-up of pressure in the tank equal to or greater than 82.5% of the tank test pressure. If pressure-relief devices of the fusible plug type are used, the required discharge capacity must be available in each head.

8.5.13.3

For the purpose of calculating discharge capacity, the applicable formula specified in Appendix A of the AAR Specifications for Tank Cars publication must be used.

8.5.13.4

Threads for openings must be NGT tapped to gauge, clean cut, even, and without checks.

8.5.13.5

Pressure-relief devices must be set for start to discharge and rupture discs must burst at a pressure equal to or less than that specified in clause 8.5.19.1.

8.5.13.6

Fusible plugs must function at a temperature equal to or less than 79.4°C (175°F) and must be vapour tight at a temperature equal to or greater than 54.4°C (130°F).

8.5.14 Pressure and Leak Testing

8.5.14.1

After post-weld heat treatment, each ton container must be subjected to a hydrostatic expansion test in a water jacket or be tested using a direct expansion method. The test method must conform to the requirements of the CGA Pamphlet C-1 except that conformance with par. 6.5 relative to the use of a calibrated cylinder for the test system accuracy verification is not required.

8.5.14.2

No ton container must have been subjected previously to an internal pressure that is within 690 kPa (100 psi) of the test pressure.

8.5.14.3

Each ton container must be tested to the pressure specified in clause 8.5.19.1 and the pressure must be maintained for at least 30 seconds to ensure complete expansion of the ton container.

8.5.14.4

The pressure gauge must permit a measurement to an accuracy of ±1% at the test pressure and the expansion gauge must measure the total expansion to an accuracy of ± 1%.

8.5.14.5

No leaks must appear and permanent volumetric expansion must not exceed 10% of total volumetric expansion at test pressure.

8.5.14.6

After all service equipment has been installed, each ton container must be subjected to an air-pressure test at a pressure equal to or greater than 690 kPa (100 psi). A ton container successfully passes an air-pressure test when there is no evidence of yielding or leakage.

8.5.14.7

Any leaks must be repaired using the same processes that are employed in the manufacture of the ton container.

8.5.15 Testing of Pressure-relief Devices

8.5.15.1

Each reclosing pressure-relief device must be tested with air or gas and must open and be vapour tight at the pressures specified in clause 8.5.19.1.

8.5.15.2

Rupture discs of non-reclosing pressure relief devices must be tested in conformance with the requirements set out in par. A5.3 of the AAR Specifications for Tank Cars publication.

8.5.15.3

For pressure-relief devices of the fusible plug type, a representative sample of the plug used must have functioned at the temperatures specified in clause 8.5.13.6.

8.5.15.4

The start to discharge and vapour tight pressures must not be affected by an auxiliary closure.

8.5.16 Permanent Markings

8.5.16.1

The following information must be plainly and permanently stamped in letters and figures equal to or greater than 10 mm (3/8 in.) in height into the metal of the valve end chime of each tank:

1. Specification;
2. Ton container material and the cladding material designation, if any, stamped immediately below the specification number;
3. The owner's or manufacturer's identifying symbol and serial number, stamped immediately below the material identification;
4. The mark of the independent inspector referred to in clause 8.5.17, stamped immediately below the owner's or manufacturer's identifying symbol;
5. Date of original tank test (month and year, such as 1 10 for January 2010), which must be stamped so as to allow the easy addition of subsequent test date; and
6. The water capacity — 0000 lb.

8.5.16.2

A copy of the above stamping in letters and figures of the specified height may be stamped on a brass plate and secured to one of the tank heads.

8.5.16.3

The owner or manufacturer's identifying symbol must be registered with Transport Canada.

8.5.17 Inspection

8.5.17.1

Each ton container must be inspected during manufacturing by an independent inspector registered under clause 6.5.

8.5.17.2

The independent inspector must verify that all plates from which the ton container are to be made conform to the specification and must obtain and review the records certifying that the plates conform to the specification.

8.5.17.3 

The independent inspector must reject plates that do not conform to the requirements set out in clause 8.5.6.

8.5.17.4

The independent inspector must perform the inspections that are required to ensure that each ton container conforms to the requirements set out in this section, including the requirements for the marking, post-weld heat treatment and testing.

8.5.17.5

The independent inspector must stamp his official mark in conformance with clause 8.5.16 on each ton container that is accepted by the inspector as being in conformance with the requirements set out in this section and must provide the report required under clause 8.5.18.

8.5.18 Report

Before a tank is placed into service, the independent inspector must provide the manufacturer, ton container owner, and Director with a report certifying that the ton container and its equipment conform to the requirements of this standard.

8.5.19 Individual Specification Requirements Applicable to TC Ton Containers

8.5.19.1 Individual Specification Requirements

In addition to the other requirements set out in clause 8.5.1, a TC ton container must conform to the individual specification requirements corresponding to the specification set out in the following table:

TC Specification	106A500X	106A800X	110A500W	110A600W	110A800W	110A1000W
Minimum Burst Pressure, bar (psi) (clause 8.5.4)	None specified	None specified	86.3 (1250)	103.4 (1500)	137.9 (2000)	172.4 (2500)
Minimum Shell Thickness, mm (in.)	10.3 (13/32)	17.4 (11/16)	8.7 (11/32)	9.5 (3/8)	11.9 (15/32)	15.0 (19/32)
Tank Test Pressure, bar (psi) (clause 8.1.14)	34.5 (500)	55.2 (800)	34.5 (500)	41.4 (600)	55.2 (800)	69.0 (1000)
Pressure-relief Device Maximum Start-to-discharge or Burst Pressure, kPa (psi)	1896 (375)	4137 (600)	2585 (375)	3102 (450)	4137 (600)	4826 (700)
Pressure-relief Device Minimum Vapour-tight Pressure, kPa (psi)	2069 (300)	3310 (480)	2069 (300)	2482 (360)	3310 (480)	4482 (650)

8.6 General Requirements Applicable to Class TC 113 Vacuum-insulated Tank Car Tanks for Cryogenic Liquids

8.6.1 General

A TC Specification 113 vacuum-insulated tank car must conform to the requirements set out in this clause and any other applicable requirements of this standard.

8.6.2 Type

A Specification 113 tank car tank must conform to the following requirements:

1. consist of an inner tank of circular cross section supported essentially concentric within an outer jacket of circular cross section, with the out-of-roundness of both the inner tank and outer jacket limited in accordance with the requirements set out in Section VIII, Division I, par. UG-80 of the ASME Code;
2. have the annular space evacuated, after filling the annular space with an insulating material;
3. have the inner tank heads concave outward;
4. have the outer jacket heads convex outward; and
5. be equipped with piping systems for the venting of vapour and the transfer of the dangerous goods and with pressure-relief devices and other service equipment as specified in this section.

8.6.3 Insulation System and Performance Standard

A Specification 113 tank car tank must conform to the following requirements:

8.6.3.1 Nomenclature

1. Standard Heat Transfer Rate (SHTR), expressed in kJ/day/kg (Btu/day/lb.) of water capacity, means the rate of heat transfer used for determining the satisfactory performance of the insulation system, as set out in the table of clause 8.6.24.1;
2. test refrigerated liquid means the refrigerated liquid, which may be different from the dangerous goods intended to be shipped in the tank car tank, being used during the performance tests of the insulation system;
3. Normal Evaporation Rate (NER), expressed in kg (lb.) of the refrigerated liquid per day, means the rate of evaporation, determined by test, known as the NER test, of a test refrigerated liquid in a tank maintained at a pressure of approximately one bar (atmosphere), absolute;
4. stabilization period means the lapsed time after a tank car tank is filled with the test refrigerated liquid until the NER has stabilized or 24 h has passed, whichever is the greater; and

5. the Calculated Heat Transfer Rate (CHTR) is calculated using the following formula which uses test data obtained during the NER test:

    

   
    

   where:

   q = CHTR, in kJ/day/kg (Btu/day/lb.) of water capacity

   N = NER, determined by NER test, in kg/day (lb./day)

   Δh = latent heat of vaporization of the test refrigerated liquid at the NER test pressure of approximately one bar (atmosphere), absolute, in kJ/kg (Btu/lb.)

   T = ambient temperature of 32.2°C (90°F)

   t₁ = equilibrium temperature of the intended dangerous goods at maximum shipping pressure, in degrees centigrade (Fahrenheit)

   V = water volume, at 15.6°C (60°F), of the inner tank, in L (US gallons)

   ρ = specific gravity of water at 15.6°C (60°F), 1 kg/L (8.328 lb./US gallon)

   t_s = average temperature of the outer jacket, determined by averaging jacket temperatures at various locations on the jacket at regular intervals during the NER test, in degrees centigrade (Fahrenheit)

   t_f = equilibrium temperature of the test refrigerated liquid at the NER test pressure of approximately one bar (atmosphere), absolute, in degrees centigrade (Fahrenheit)

8.6.3.2

A Specification 113A60W tank car must:

a. be filled with hydrogen, refrigerated liquid to the maximum permitted filling density specified in special provision 69 f., Schedule 1, Appendix E, before the NER test is conducted; and

b. have a CHTR equal to or less than the SHTR specified in the table of clause 8.6.24.1 for a Specification 113A60W tank car.

8.6.3.3

A Specification 113C120W tank car must:

1. be filled with:
2. ethylene, refrigerated liquid to the maximum permitted filling density specified in special provision 69 f., Schedule 1, Appendix E, before the NER test is conducted; or
   1. nitrogen, refrigerated liquid to 90% of the volumetric capacity of the inner tank before the NER test is conducted; and
   2. have a CHTR equal to or less than 75% of the SHTR specified in the table of clause 8.6.24.1 for a TC Specification 113C120W tank car.

8.6.3.4

If the insulation consists of a powder susceptible to settlement, the entire top of the cylindrical portion of the inner tank must be insulated with a layer of glass fibre insulation equal to or greater than 25 mm (1 in.) nominal thickness or equivalent, held in position and covering an area extending 25° to each side of the top centreline of the inner tank.

8.6.3.5

The outer jacket must be equipped with service equipment to permit evacuation of the annular space between the outer jacket and the inner tank.

8.6.3.6

The outer jacket must be equipped with a system to measure the absolute pressure in the annular space. The system must be permanently positioned so as to be easily visible or provide an easily accessible connection for the use of a portable device.

8.6.4 Metal Plate

8.6.4.1

Stainless steel of ASTM Specification A240/A240M, Type 304, or 304L must be used for the inner tank and its service equipment, as set out in Appendix M of the AAR Specifications for Tank Cars publication and must be in the annealed condition prior to fabrication, forming and fusion welding.

8.6.4.2

The outer jacket shell and heads must be made from steel specified in clause 8.3.5. Any steel casting, steel forging, steel structural shape, attached to the outer jacket or heads must be as set out in Appendix M of the AAR Specifications for Tank Cars publication.

8.6.4.3

Impact tests must be:

1. conducted in accordance with the requirements set out in par. W9.1 of the AAR Specifications for Tank Cars publication;
2. performed on specimens of the material taken in the longitudinal direction of rolling;
3. performed when the design service temperature is less than -195.5°C (-320°F);
4. performed at a temperature equal to or less than the tank design service temperature; and
5. performed on test plate welds and materials that are used to manufacture the inner tank and service equipment and that are subject to the refrigerated liquid temperatures.

8.6.4.4

Impact test results must be equal to or greater than those set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.6.4.5

The report of impact tests must include the absorbed energy results and the lateral expansion data for each tested specimen.

8.6.5 Burst and Buckling Pressure

8.6.5.1

The inner tank must have a burst pressure equal to or greater than that specified in clause 8.6.24.1.

8.6.5.2

The outer jacket must be designed in accordance with the requirements set out in clauses 8.6.7.4 and 8.6.7.5, and must conform to the design loads and stresses specified in par. 6.2 of the AAR Specifications for Tank Cars publication. The designs and calculations must take into account the loads transferred to the outer jacket through the support system.

8.6.6 Heads

8.6.6.1

A tank head of the inner tank and outer jacket must be flanged and dished, or have the form of an ellipsoid of revolution.

8.6.6.2

A flanged and dished head must have:

1. a main inside dish radius equal to or less than the outside diameter of the straight flange;
2. an inside knuckle radius equal to or greater than 6% of the outside diameter of the straight flange; and
3. an inside knuckle radius equal to or greater than three times the head thickness.

8.6.7 Minimum Thickness

8.6.7.1

The minimum wall thickness, after forming, of the inner tank shell and any 2:1 ellipsoidal inner tank head must be the greater of:

1. the applicable minimum plate thickness of the shell and the applicable minimum head thickness specified in clause 8.6.24.1; or

2. the thickness calculated using the following formula:

    

   
    

   where:

   t = minimum thickness of plate material, in mm (in.), after forming

   P = minimum burst pressure, in bar (psi)

   d = inside diameter, in cm (in.)

   S = minimum tensile strength of the plate material, as set out in Table M10.3, of the AAR Specifications for Tank Cars publication, in MPa (psi)

   E = 0.9, a factor representing the efficiency of welded joints, except that for seamless heads, E = 1.0

8.6.7.2

The minimum wall thickness, after forming, of any 3:1 ellipsoidal inner tank head must be the greater of:

1. the minimum head thickness specified in clause 8.6.24.1; or

2. the thickness calculated using the following formula:

    

   
    

   where:

   t = minimum thickness of plate material, in mm (in.), after forming

   P = minimum burst pressure, in bar (psi)

   d = inside diameter, in cm (in.)

   S = minimum tensile strength of the plate material, as set out in Table M10.3, of the AAR Specifications for Tank Cars publication, in MPa (psi)

   E = 0.9, a factor representing the efficiency of welded joints, except that for seamless heads, E = 1.0

8.6.7.3

The minimum wall thickness, after forming, of a flanged and dished head for the inner tank must be the greater of:

1. the minimum head thickness specified in clause 8.6.24.1; or
2. the thickness calculated using the following formula:

    

   
    

   where:

   t = minimum thickness of plate, in mm (in.), after forming

   P = minimum burst pressure, in bar (psi)

   L = main inside radius of dished head, in cm (in.)

   r = inside knuckle radius, in cm (in.)

   S = minimum tensile strength of plate material, as set out in Table M10.3, of the AAR Specifications for Tank Cars publication, in MPa (psi)

   E = 0.9, a factor representing the efficiency of welded joints, except that for seamless heads, E = 1.0

8.6.7.4

The minimum wall thickness, after forming, of the outer jacket shell must be equal to or greater than 11 mm (7/16 in.).

8.6.7.5

The minimum wall thickness, after forming, of the outer jacket heads must be equal to or greater than 13 mm (1/2 in.).

8.6.7.6

The annular space must be evacuated and the cylindrical portion of the outer jacket between the heads, or between the stiffening rings if stiffening rings are used, must be designed to withstand an external critical collapsing pressure equal to or greater than 0.259 MPa (37.5 psi), as calculated using the following formula:

 

where:

P_c = critical collapsing pressure equal to or greater than 0.259 MPa (37.5 psi)

E = modulus of elasticity of outer jacket material, in MPa (psi)

t = minimum thickness of outer jacket material, in mm (in.), after forming

D = outside diameter of outer jacket, in mm (in.)

L = distance between stiffening ring centres, in mm (in.) (The outer jacket heads may be considered as stiffening rings located one-third of the head depth from the head tangent line.).

8.6.8 Stiffening Rings

8.6.8.1

If stiffening rings are used in designing the outer jacket shell for external pressure:

1. the stiffening rings must be attached to the outer jacket by means of fillet welds;
2. outside stiffening ring attachment welds must be continuous on each side of the ring;
3. inside stiffening ring attachment welds may be intermittent welds on each side of the ring and the total length of weld on each side must be equal to or greater than one-third of the circumference of the tank; and
4. the maximum space between welds must not exceed eight times the outer jacket wall thickness.

8.6.8.2

A portion of the outer jacket may be included when calculating the moment of inertia of the ring.

8.6.8.3

The effective width of jacket plate on each side of the attachment of the stiffening ring must be the width calculated using the following formula:

 

where:

W = width of jacket effective on each side of the stiffening ring, in mm (in.)

R = outside radius of the outer jacket, in mm (in.)

t = plate thickness of the outer jacket, in mm (in.), after forming.

8.6.8.4

If a stiffening ring is used that consists of a closed section having two webs attached to the outer jacket:

1. the jacket plate between the webs may be included up to the limit of twice the value of "W," as defined in clause 8.6.8.3;
2. the outer flange of the closed section, if not a steel structural shape, is subject to the same limitations of "W" as in clause 8.6.8.4 a., based on the "R" and "t" values of the flange as defined in clause 8.6.8.3;
3. if two separate members, such as two angles, are located less than twice the value of "W" apart, as defined in clause 8.6.8.3, they may be treated as a single stiffening ring member;
4. the maximum length of plate, which may be considered effective, is four times the value of "W", as defined in clause 8.6.8.3; and
5. the closed section between an external ring and the outer jacket must be provided with an opening for drainage.

8.6.8.5

The stiffening ring must have a moment of inertia large enough to support the critical collapsing pressure, as calculated using one of the following formulas:

 

or

 

where:

I = required moment of inertia of stiffening ring about the centroidal axis parallel to the outer jacket axis, in mm (in.) to the fourth power

I′ = required moment of inertia of combined section of stiffening ring and effective width of jacket plate about the centroidal axis parallel to the outer jacket axis, in mm (in.) to the fourth power

D = outside diameter of the outer jacket, in mm (in.)

L = one-half of the distance from the centre line of the stiffening ring to the next line of support on one side plus one-half of the distance from the centreline to the next line of support on the other side of the stiffening ring. Both distances are to be measured parallel to the axis of the vessel, in mm (in.). A line of support is:

1. a stiffening ring that conforms to the requirements of this paragraph; or
2. a circumferential line of a head at one-third the depth of the head from the tangent line.

P_c = critical collapsing pressure equal to or greater than 0.259 MPa (37.5 psi)

E = modulus of elasticity of stiffening ring material, in MPa (psi).

8.6.8.6

If loads are applied to the outer jacket or to stiffening rings from the supports of the inner tank, additional stiffening rings or an increased moment of inertia of the stiffening rings designed for the external pressure must be provided to carry the support loads.

8.6.9 Sump or Siphon Bowl

A sump or siphon bowl must not be installed unless it is located in the bottom of the inner tank shell and conforms to the following requirements:

1. it is formed directly into the inner tank shell or if it is formed and welded to the inner tank shell, it must be made of metal that is weldable to the metal of the inner tank shell;
2. the stress in any orientation under any condition is equal to or less than the circumferential stress in the inner tank shell; and
3. the wall thickness is equal to or greater than that specified in clause 8.6.24.1.

8.6.10 Welding

8.6.10.1

Except for closure of openings and a maximum of two circumferential closing joints in the outer jacket shell, each joint of an inner tank and the outer jacket must be a fusion, double-welded butt joint.

8.6.10.2

The closure for openings and the circumferential closing joints in the outer jacket shell, including head-to-shell joints, may be a single-welded butt joint using a backing strip on the inside of the joint.

8.6.10.3

Each joint must be welded in accordance with the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.6.11 Post-weld Heat Treatment

8.6.11.1

Post-weld heat treatment of the inner tank is not required.

8.6.11.2

The outer jacket shell, with the exception of the circumferential closing seams, must be post-weld heat-treated as set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.6.11.3

Any item to be welded to the outer jacket shell must be welded before post-weld heat treatment.

8.6.11.4

Welds securing the following need not be post-weld heat-treated if such post-weld heat treatment is not practical due to final assembly procedures:

1. the inner tank support system to the outer jacket;
2. connections at piping penetrations;
3. closures for access openings; and
4. circumferential closing joints of head-to-shell joints.

8.6.11.5

If cold-formed heads are used on the outer jacket and post-weld heat treatment is not practical due to assembly procedures, the cold-formed heads must be heat-treated before they are welded to the outer jacket shell.

8.6.12 Support System for Inner Tank

8.6.12.1

The inner tank must be supported within the outer jacket by a support system.

8.6.12.2

The strength and ductility, at operating temperatures, of the support system and its areas of attachment to the outer jacket must be capable of supporting the inner tank when filled with the dangerous goods to any level during normal conditions of transport.

8.6.12.3

The support system must be designed to support, without yielding, impact loads producing accelerations of the following magnitudes and directions when the inner tank is fully loaded and the tank car is equipped with a conventional AAR M-901 draft gear:

1. Longitudinal 7g
2. Transverse 3g
3. Vertical 3g

8.6.12.4

The longitudinal acceleration may be reduced to 3g if a cushioning device, which has been tested to demonstrate its ability to limit tank car tank forces to a maximum of 1779 kN (400 000 lb.) at an impact speed of 16 km/h (10 mph), is used between the coupler and the tank structure.

8.6.12.5

The inner tank and outer jacket must be electrically bonded to each other by the support system used, by piping, or by a separate electrical connection.

8.6.13 Radiography

Each longitudinal and circumferential joint of the inner tank and each longitudinal and circumferential double-welded butt joint of the outer jacket must be examined along its entire length in conformance with the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.6.14 Access to Inner Tank

8.6.14.1

The inner tank must be provided with an access opening having a minimum inside diameter of 406 mm (16 in.). Reinforcement of the access opening must be made of the same material used for the inner tank.

8.6.14.2

If a welded closure is used, the closure must be designed to allow it to be reopened by grinding or chipping and to be closed again by re-welding without a need for new parts. A cutting torch must not be used.

8.6.15 Inner Tank Piping

8.6.15.1

In the case of piping lines for the liquid and gas phase of the refrigerated liquid:

1. the piping system or vapour and liquid-phase transfer and venting system must be made of materials that are compatible with the dangerous goods and that are suitable for use at the temperature of the dangerous goods;
2. the outlets of all vapour-phase and liquid phase lines must be located so that accidental discharge from the lines will not impinge on any metal of the outer jacket, car structures, trucks, or safety appliances; and
3. provision must be made to allow for thermal expansion and contraction.

8.6.15.2

In the case of loading and unloading lines:

1. a liquid-phase transfer line must be provided and it must have a manually-operated shut-off valve located as close as practicable to the outer jacket plus a secondary closure that is liquid-tight and gas-tight;
2. the secondary closure must permit any trapped pressure to bleed off before the closure can be removed completely;
3. a vapour trap must be incorporated into the line and located as close as practicable to the inner tank; and
4. on a Specification 113A60W tank car tank, any loading and unloading line must be vacuum-jacketed between the outer jacket and the shut-off valve and the shut-off valve must also be vacuum-jacketed.

8.6.15.3

In the case of a vapour-phase line:

1. the vapour-phase line must be connected to the inner tank and must be of sufficient size to permit the pressure-relief devices that are specified in clause 8.6.18 and that are connected to the vapour-phase line to operate at their design capacity without excessive pressure build-up in the tank;
2. the vapour-phase line must have a manually operated shut-off valve located as close as practicable to the outer jacket plus a secondary closure that is liquid-tight and gas-tight; and
3. the secondary closure must permit any trapped pressure to bleed off before the closure can be removed completely.

8.6.15.4

In the case of a vapour-phase blowdown line, the blowdown line must conform to the following requirements:

1. a blowdown line must be provided;
2. the blowdown line must be attached to the vapour-phase line specified in clause 8.6.15.3, upstream of the shut-off valve in that line;
3. a by-pass line with a manually operated shut-off valve must be provided to allow a reduction of the inner tank pressure when the vapour-phase line is connected to a closed system; and
4. the discharge from this line must be outside the housing and must be directed upward and away from operating personnel.

8.6.16 Pressure Testing of the Inner Tank

8.6.16.1

After all required items have been welded in place to the inner tank, the inner tank must be pressure-tested at the tank test pressure specified in clause 8.6.24.1.

8.6.16.2

The temperature of the pressurizing medium must be equal to or less than 37.8°C (100°F) during the test.

8.6.16.3

The inner tank must hold the specified tank test pressure for a period of not less than 10 min without evidence of yielding or leakage.

8.6.16.4

After a hydrostatic test, the inner tank and piping must be emptied of all water and purged of all water vapour.

8.6.16.5

Repairs to welded joints that have developed leaks during the test must be made in conformance with the requirements set out in Appendix W of the AAR Specifications for Tank Cars publication.

8.6.17 Valves and Gauges

8.6.17.1

Manually operated shut-off valves and control valves must be provided wherever needed for the control of vapour-phase pressure, vapour-phase venting, liquid transfer and liquid-flow rates.

8.6.17.2

Valves must conform to the following requirements:

1. All valves must be made from materials that are compatible with the dangerous goods and that are suitable for use at the temperature of the dangerous goods;
2. Liquid control valves must have an extended stem design;
3. Packing, if used, must be compatible with the dangerous goods and be of materials that will seal the valve stem without causing difficulty of operation; and
4. Each control valve and shut-off valve must be readily operable. These valves must be mounted so that their operation will not transmit excessive forces to the piping system.

8.6.17.3 

Gauges must conform to the following requirements:

1. Gauges, except portable units, must be securely mounted within suitable protective housings;
2. A liquid-level gauge that indicates the quantity of liquid within the inner tank must be provided;
3. The liquid level gauge must be:
   1. a permanent gauge mounted where it will be readily visible during handling or storage;
   2. a portable gauge with a readily accessible connection; or
   3. a fixed length dip tube that:
      1. has a manually operated shut-off valve located as close as practicable to the outer jacket;
      2. indicates the maximum liquid level for the allowable filling density; and
      3. has the inner end of the dip tube located on the longitudinal centreline of the inner tank and within 1.2 m (4 ft.) of the transverse centreline of the inner tank.
4. A vapour-phase pressure gauge that indicates the vapour pressure within the inner tank must be provided; and
5. The vapour-phase pressure gauge must:
   1. have a manually operated shut-off valve located as close as practicable to the outer jacket;
   2. must be mounted where it will be readily visible; and
   3. have an additional fitting for the use of a test gauge.

8.6.18 Pressure-relief Devices

8.6.18.1 General

The tank car tank and piping system of the tank car tank must be protected by the installation of pressure-relief devices and must conform to the following requirements:

1. the discharge from the pressure-relief devices must be directed away from operating personnel, principal load-bearing members, and attachments of the outer jacket, trucks, and safety appliances;
2. vent or weep holes in the pressure-relief devices are prohibited; and
3. all main pressure-relief devices must discharge to the outside of the protective housing in which they are located, except that this requirement does not apply to pressure-relief devices installed to protect isolated sections of lines between the final valve and the end closure.

8.6.18.2 Materials

Materials used in pressure-relief devices must be compatible with the dangerous goods and suitable for use at the temperature of the dangerous goods.  

8.6.18.3 Inner Tank

The following requirements apply to the use of pressure-relief devices and safety vents for the inner tank:

1. Pressure-relief devices for the inner tank must be attached to vapour-phase piping and mounted so as to remain at ambient temperature before operation;
2. The inner tank must be equipped with one or more pressure-relief devices and one or more safety vents, except as provided in clause 8.6.18.3 e. iv., and installed without an intervening shut-off valve, except as provided in clause 8.6.18.3 e. iii.;
3. The safety vent must:
   1. function at the pressure specified in clause 8.6.24.1;
   2. be flow-rated in conformance with the applicable requirements set out in Appendix A of the AAR Specifications for Tank Cars publication; and
   3. provide sufficient capacity to conform to the requirements set out in Appendix A of the AAR Specifications for Tank Cars publication.
4. The pressure-relief device must:
   1. be set to start-to-discharge at the pressure specified in clause 8.6.24.1; and
   2. conform to the requirements set out in Appendix A of the AAR Specifications for Tank Cars publication;
5. Installation of Safety Vent and Pressure-relief Device
   1. Inlet Piping
      1. The opening through all piping and other service equipment between the inner tank and its pressure-relief devices must have a cross-sectional area equal to or greater than that of the pressure-relief device inlet and the flow characteristics of this upstream system must be such that the pressure drop will not adversely affect the relieving capacity or the proper operation of the pressure-relief device;
      2. If the required relief capacity is met by the use of a multiple pressure-relief device placed on one connection, the inlet internal cross-sectional area of this connection must be sufficient to provide the required flow capacity for the proper operation of the pressure-relief device system;
   2. Outlet Piping
      1. The opening through the discharge lines must have a cross-sectional area equal to or greater than that of the pressure-relief device outlet and must not reduce the relieving capacity below that required to properly protect the inner tank;
      2. If the required relieving capacity is met by the use of multiple pressure-relief devices placed on a common discharge manifold, the manifold outlet internal cross-sectional area must be equal to or greater than to the combined outlet areas of the pressure-relief devices;
   3. Duplicate pressure-relief devices may be used if a three-way selector valve is installed to provide for relief through either pressure-relief device. The three-way selector valve must be included in the mounting set out in par. A6.2.6 of the AAR Specifications for Tank Cars publication, when conducting the flow capacity test on the safety vent set out in par. A6.1 of the AAR Specifications for Tank Cars publication. Flow capacity tests must be performed with the three-way valve at both of the extreme positions as well as at the mid-position and the flow capacity must be in conformance with the requirements set out in Appendix A of the AAR Specifications for Tank Cars publication;
   4. An alternate pressure-relief device in conformance with the requirements set out in clause 8.6.24.1 may be used in lieu of the safety vent, provided it conforms to the flow capacity set out in Appendix A of the AAR Specifications for Tank Cars publication at a flow rating pressure of 110% of its start-to-discharge pressure. Installation must:
      1. prevent moisture accumulation at the seat by providing drainage away from that area;
      2. permit periodic drainage of the vent piping; and
      3. prevent accumulation of foreign material in the vent system;
6. Evaporation Control — The normal release of vaporized dangerous goods may be controlled with a pressure controlling and mixing device. A pressure controlling and mixing device is required on a Specification 113A60W tank car tank. Any pressure controlling and mixing device must:
   1. be set to start to discharge at a pressure equal to or less than that specified in clause 8.6.24.1;
   2. have sufficient capacity to limit the pressure within the inner tank to that pressure specified in clause 8.6.24.1, when the discharge is equal to twice the normal venting rate during transport, with normal vacuum and the outer shell at 54.4°C (130°F); and
   3. prevent the discharge of a gas mixture greater than 50% of the lower flammability limit to the atmosphere under normal conditions of handling or transport;
7. Safety Interlock — If a safety interlock is provided for the purpose of allowing transfer of dangerous goods at a pressure greater than the pressure-control valve setting and less than the pressure-relief device setting, the design must be such that the safety interlock will not affect the discharge path of the pressure-relief device or safety vent at any time. The safety interlock must automatically provide an unrestricted discharge path for the pressure-control device at all times during transport.

8.6.18.4 Outer Jacket

The outer jacket must be provided with a suitable system to prevent build-up of annular space pressure to a pressure greater than 110 kPa (16 psi) or greater than the external pressure value for which the inner tank was designed, whichever is the lesser. The total relief area provided by the system must be equal to or greater than 16 129 mm2 (25 in.2) and means must be provided to prevent clogging of any system opening and to provide for adequate communication to all areas of the insulation space. If a safety vent is a part of the system, it must be designed to prevent distortion of the rupture disc when the annular space is evacuated.

8.6.18.5 Piping System

If a piping circuit can be isolated by closing a valve, means for relieving any trapped pressure must be provided.

8.6.19 Test of Pressure-relief Valves

Each valve, before being put into service, must be tested with air or another gas for conformance with the requirements set out in clause 8.6.24.1.

8.6.20 Protective Housings

8.6.20.1

Each valve, gauge, closure, and pressure-relief device, with the exception of secondary relief valves for the protection of isolated piping, must be enclosed within a protective housing.

8.6.20.2

The protective housing must be adequate to protect the enclosed service equipment from direct solar radiation, mud, sand, adverse environmental exposure, and mechanical damage encountered during the normal handling or transport of the tank car.

8.6.20.3

The protective housing must be designed to:

1. provide reasonable access to the enclosed service equipment for operation, inspection, and maintenance; and
2. prevent vapour concentration build up to a dangerous level inside the housing in the event of valve leakage or pressure-relief device operation.

8.6.20.4

All equipment within the protective housing must be operable by personnel wearing heavy gloves and must incorporate provisions for locks or seals.

8.6.20.5

A protective housing and its cover must be manufactured of metal equal to or greater than 3.0 mm (0.119 in.) in thickness.

8.6.21 Operating Instructions

8.6.21.1

All valves and gauges must be clearly identified with corrosion-resistant nameplates

8.6.21.2

A plate of corrosion-resistant material bearing precautionary instructions for the safe operation of the equipment during handling operations must be securely mounted so as to be readily visible.

8.6.21.3

The instruction plate must be mounted in each housing that contains service equipment and controls.

8.6.21.4

The precautionary instructions on the plate must include a diagram of the tank and its piping system with the various gauges, control valves, and pressure-relief devices clearly identified and located.

8.6.22 Permanent Markings

Subject to clause 7.3 the marking on a Specification 113 tank car tank must conform to the following requirements:

8.6.22.1

Each tank must have permanent markings, including:

1. tank specification;
2. design service temperature;
3. material specification of the inner tank;
4. as-built thickness of the shell and heads of the inner tank;
5. inside diameter;
6. inner tank manufacturer's identifying mark;
7. month and year of the original tank test of the inner tank;
8. water capacity of the inner tank;
9. material specification of the outer jacket;
10. initials assigned to the outer jacket manufacturer; and
11. identifying mark of the tank car assembler if different from the inner tank or outer jacket manufacturer.

8.6.22.2

The permanent markings must be stamped in the order set out in clause 8.6.22.1 in letters and figures equal to or greater than 10 mm (3/8 in.) in height into the metal near the centre of the head of the outer shell located at the B-end of the tank car. The inner container heads must not be stamped. The following is an example of the required markings:

8.6.23 Stencilling

Each tank car must be stencilled in conformance with the requirements set out in Appendix C of the AAR Specifications for Tank Cars publication. The stencilling must include the following information:

1. The date on which the rupture disc was last replaced and the initials of the person making the replacement, on the outer jacket in letters and figures equal to or greater than 38 mm (1½ in.) in height;
2. The design service temperature and maximum dangerous goods mass, adjacent to the dangerous goods identification stencil in letters and figures equal to or greater than 38 mm (l½ in.) in height;
3. The water capacity, in pounds at 60°F, with the tank at its coldest operating temperature and after deduction for the volume above the inlet to the pressure-relief device or pressure-control valve, structural members, baffles, piping, and other service equipment inside the tank, in letters and figures equal to or greater than 38 mm (1½ in.) in height;
4. The statement "DO NOT HUMP OR CUT OFF WHILE IN MOTION" or "DO NOT HUMP OR CUT OFF WHILE IN MOTION/DÉFENSE DE PASSER SUR LA BUTTE DE TRIAGE OU DE DÉTELER EN MOUVEMENT," on both sides of the tank car, in letters equal to or greater than 38 mm (1½ in.) in height; and
5. The statement "VACUUM-JACKETED" or "VACUUM-JACKETED/CHEMISE SOUS VIDE," on the outer jacket below the specification stencil, in letters equal to or greater than 38 mm (1½ in.) in height.

8.6.24 Individual Specification Requirements Applicable to Inner Tanks and Service Equipment for TC Specification 113 Vacuum-insulated Tank Car Tanks for Cryogenic Liquids

8.6.24.1 Individual Specification Requirements

In addition to requirements set out in clause 8.6.1, the inner tank and service equipment for a tank car for cryogenic liquids must conform to the individual TC Specification requirements corresponding to the specification set out in the following table:

TC Specification	113A60W	113C120W	113C140W	113A90W
Design service temperature	-253°C (-423°F)	-162°C (-260°F)	-162°C (-260°F)	-195.5°C (-320°F)
Materials	Clause 8.6.4	Clause 8.6.4	Clause 8.6.4	Clause 8.6.4
Impact test (weld and plate material)	Clause 8.6.4.3	Clause 8.6.4.3	Clause 8.6.4.3	Clause 8.6.4.3
Impact test values	Clause 8.6.4.4	Clause 8.6.4.4.	Clause 8.6.4.4.	Clause 8.6.4.4.
Standard heat transfer rate, kJ/day/kg (Btu/day/lb.) of water capacity, maximum (see clause 8.6.3)	0.2256 (0.097)	0.9585 (0.4121)	0.9585 (0.4121)	13.49? (5.8)
Bursting pressure, minimum, bar (psi)	16.6 (240)	20.7 (300)	24.8 (360)	16.55 (240)
Plate thickness shell, minimum, mm (in.) (see clause 8.6.7.1)	4.7 (3/16)	4.7 (3/16)	4.7 (3/16)	4.7 (3/16)
Head thickness, minimum, mm (in.) (see clause 8.6.6)	4.7 (3/16)	4.7 (3/16)	4.7 (3/16)	4.7 (3/16)
Tank test pressure, bar (psi) (see clause 8.6.16)	414 (60)	827 (120)	9.65 (140)	6.21 (90)
Safety vent bursting pressure, maximum, kPa (psi)	414 (60)	827 (120)	9.65 (140)	6.21 (90)
Pressure-relief device start-to-discharge pressure, ±20 kPa (±3 psi)	207 (30)	517 (75)	6.21 (90)	4.14 (60)
Pressure-relief device vapour-tight pressure, minimum kPa (psi)	165 (24)	414 (60)	4.96 (72)	3.31 (48)
Pressure-relief device flow rating pressure, maximum, kPa (psi)	275 (40)	586 (85)	6.90 (100)	4.55 (66)
Alternate pressure-relief device start-to-discharge pressure, ±20 kPa (±3 psi)	—	621 (90)	7.45 (108)	4.97 (72)
Alternate pressure-relief device vapour-tight pressure, minimum, kPa (psi)	—	496 (72)	5.93 (86)	4.0 (58)
Alternate pressure-relief device flow rating pressure, maximum, kPa (psi)	—	689 (100)	8.27 (120)	5.52 (80)
Pressure-control valve start-to-vent, maximum, kPa (psi) (see clause 8.6.18.3 f.)	117 (17)	Not required	Not required	Not required
Relief device discharge restrictions	Clause 8.6.18	Clause 8.6.18	Clause 8.6.18	Clause 8.6.18
Transfer line insulation	Clause 8.6.15	Not required	Not required	Not required

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