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Rules for the Installation, Inspection & Testing of Air Reservoirs (Other than on Locomotives)

Legislation (Rail Safety)

TC O-0-10, December 1994



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Table of Contents

Part I - General

Part II - Filing Requirements

APPENDIX I: Specification and Inspection Report for Air Reservoirs and Associated Components



Part I - General

1. Short Title

1.1 For ease of reference, this rule may be referred to as the "Air Reservoir Rule".

2. Scope

2.1 These rules prescribe the standards for installation, inspection, testing and reporting of air reservoirs used by railway companies subject to the jurisdiction of Transport Canada. These rules apply to stationary and portable reservoirs except those on locomotives.

3. Definitions:

In these rules:

3.1 "air reservoir" means a tank of air larger than 5 cubic feet and under pressure greater than 15 pounds per square inch;

3.2 "automatic drain valve" means a device which automatically drains condensate from the air reservoir supply system;

3.3 "department" means the Department of Transport, Surface Group;

3.4 "design pressure" means the maximum permissible internal operating pressure for a vessel in its normal operating position at the operating temperature specified for that pressure, and includes a factor of safety of 4.

3.5 "factor of safety" means a margin of safety and is used to determine maximum allowable stress value used for the design of the reservoir;

3.6 "authorized working pressure" means the pressure at which a vessel is authorized to operate; it must always be less than the design pressure;

3.7 "hydrostatic testing" means a test capable of pressurizing the reservoir to a minimum test pressure of 1 ¼ times the maximum authorized working pressure (as prescribed on the badge plate);

3.8 "railway company" means a railway or railway company subject to the Railway Safety Act;

3.9 "railway safety inspector" means a Department of Transport inspector appointed pursuant to section 27 of the Railway Safety Act;

3.10 "telltale drilled" means a reservoir drilled to a pre-determined depth over its entire surface, both shell and heads, using a standard 3/16 inch drill.

4. General

4.1 A railway company is responsible to ensure that all air reservoirs, associated piping, pressure gauges and safety valves attached thereto, are safely maintained.

4.2 A railway company shall prepare and distribute suitable air reservoir maintenance guidelines to railway staff which upon request shall be made available to a railway safety inspector. These guidelines will include authorized working pressure.

4.3 Any reservoir developing leakage through a telltale hole or corrosion of the reservoir steel plate, shall be permanently removed from service.

4.4 Any newly installed reservoir shall be telltale drilled using the procedures in section 8.2.

5. Reservoir Installation Requirements

5.1 Identification

A serial number and the authorized working pressure shall be plainly stamped in figures not less than 1/4 inch high on a metal plate, and the metal plate fastened to the reservoir in a conspicuous location.

5.2 Pressure Gauges

Each stationary air reservoir system shall be equipped with a pressure gauge graduated to at least fifty per cent above the safety valve setting.

5.3 Safety Valves

  1. Capacity: All air pressure systems shall carry a safety valve or valves of approved design in an approved location and of the capacity specified to suit conditions of the individual service. In this section, "approved" refers to the current version of Section 1, ASME Boiler and Pressure Vessel Codes.
  2. Adjustment: Safety valves shall be set at a pressure not to exceed 6 pounds above the authorized working pressure, and never above the design pressure.

5.4 Drain Valve

Every air reservoir shall be provided with an automatic or manual drain valve connected to the lowest part of the reservoir.

5.5 Setting

Reservoirs shall be set up on supports, so that the bottom of the reservoir is clear of the ground and ample space for a drain valve is provided.

6. Inspection and Hydrostatic Testing

6.1 Reservoirs will be inspected to verify condition of reservoir system, air gauges and safety valves. Air gauges and safety valves shall be inspected annually. Defective components will be replaced.

6.2 Inspections and hydrostatic testing will be performed:

  1. following telltale drilling;
  2. following a modification to the reservoir; and
  3. according to the following schedule:
  INSPECTION FREQUENCY  
TYPE OF RESERVOIR STATIONARY PORTABLE HYDROSTATIC TESTING
Corrosion resistant steel Once every 10 years To be included with routine inspection of main equipment Not required
Telltale drilled, welded Once every 5 years To be included with routine inspection of main equipment Not required
Undrilled, welded Once every 3 years To be included with routine inspection of main equipment Once every 3 years
Rivetted Annually Annually Annually

7. Hydrostatic Testing Procedures

7.1 Reservoirs requiring hydrostatic testing shall be tested to a pressure at least 25 per cent greater than the working pressure authorized under 5.1. The date of the hydrostatic test shall be stencilled in not less than one inch figures at a prominent location on each reservoir.

7.2 The entire surface of an undrilled reservoir shall be hammer-tested before each hydrostatic test with reservoir under atmospheric pressure.

7.3 All undrilled air reservoirs shall be thoroughly cleaned by washing out at each hydrostatic test, so as to remove all foreign matter, and then closely examined for corrosion and pitting.

8. Telltale Drilling

8.1 General

Existing welded reservoirs may be telltale drilled using the procedures in section 8.2. Newly installed reservoirs, except those constructed of corrosion resistant steel, must be telltale drilled.

8.2 Procedures

  1. Each air reservoir, originally constructed and maintained to withstand at least four times the authorized working pressure, may be drilled over its
    entire surface both shell and heads with telltale holes, made by a standard 3/16 inch drill which shall be spaced not more than 12 inches apart, measured both longitudinally and circumferentially, and drilled from the outer surface to a minimum depth determined by the formula:

    D = 0.6 PR / (S - 0.6 P) where:

    D = minimum depth of telltale holes in inches but in no case less than 1/16
    P = design pressure in pounds per square inch;
    S = 1/5 of the minimum specified tensile strength of the material in pounds per square inch; and
    R = inside radius of the reservoir in inches;
  2. The design pressure P is obtained from:

    P = SEt / (R + 0.6t) where:

    S = 1/5 of the minimum tensile strength in pounds per square inch;
    E = joint efficiency as specified per UW-12 ASME Code Section VIII Div 1;
    t = minimum thickness of shell plate in inches; and
    R = inside radius of shell in inches;
  3. On horizontal reservoirs, one row of holes shall be drilled lengthwise in a line at the bottom of the reservoir;
  4. On vertical reservoirs one row of holes shall be drilled on a line passing through the lowest point of the reservoir;
  5. The holes drilled in each head shall be radially in line with the longitudinal rows of the holes in the shell;
  6. Flange connections, longitudinal seams or other permanent connections to the air reservoir that interfere with telltale hole lines or circles must be cleared by a least one inch.

Part II - Filing Requirements

9. Filing Requirements with the Department

9.1 Stationary Air Reservoirs

  1. Each railway company shall file with the Department a list of all air reservoirs in service;
  2. Any new air reservoirs placed in service or air reservoirs removed from service shall be filed with the Department annually;
  3. A copy of "Specification and Inspection Report for Air Reservoirs and Associated Components" form (Appendix I) will be displayed under transparent cover at or near the location of the air reservoir.

9.2 Portable Air Reservoirs

  1. Each railway company shall file with the Department a list of the air reservoirs in service;
  2. Any new air reservoirs placed in service or air reservoirs removed from service shall be filed with the Department annually; and
  3. The inspection date will be stamped or stenciled on the reservoir.

Appendix I: Specification and Inspection Report for Air Reservoirs and Associated Components

Name of Railway Company:

  • Located at or on:
  • Railway Serial No.:
  • Manufactured by:
  • Service:
  • Manufacturer's No.:
  • Design pressure:
    • Constructed at:
    • Date:
  • Authorized working pressure lb. per sq. inch:
    • Factor of safety
  • Diameter of reservoir:
  • Material of shell plates:
    • Radius of heads:
    • Top:
    • Bottom:
  • Material of heads:
    • Minimum tensile:
    • lb/sq. in.:
  • Thickness of shell plates:
    • Minimum tensile:
    • lb/sq. in.
  • Thickness of heads:
  • Number and size of manholes:
  • Position of reservoir - vertical or horizontal:
  • Number, size, make and model of safety valves:
  • Location of safety valves (on reservoir, in supply line, etc.):
  • Safety valve or valves set at:
  • Telltale drill depth:
  • The data upon which calculations were made was:
    obtained from drawing Nos.
  • Date:
    • of; the inspection:
    • the telltale drilling:
    • hydrostatic testing:
    • the annual inspection of air gauges:
    • and safety valves:
Date modified:
2009-08-27