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Subchapter 1. Unfired Pressure Vessel Safety Orders
Article 10. Safe Practices

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§560. Safe Practices.

(a) No person shall do any of the following:

(1) Remove, displace, damage, destroy, or carry off any safety device, safeguard, notice, or warning for use in any employment or place of employment or interfere in any way with their use by any other person (this is not intended to prohibit the removal for repair or maintenance of any safety device provided such device or a suitable replacement is reinstalled before the unit is replaced in service).

(2) Interfere with the use of any method or process adopted for the protection of any employee, including himself, in such employment of places of employment.

(3) Fail or neglect to do every other thing reasonably necessary to protect the life and safety of employees.

(b) The following Safety Orders from California Administrative Code, Title 8, are hereby made apart of these orders.

(1) General Industry Safety Order 3301: Use of Compressed Air or Gases. See Appendix B.

(2) General Industry Safety Order 3304: Miscellaneous Use of Compressed Cylinder Gas. See Appendix B.

(3) General Industry Safety Order 3312: Entering Combustion Chambers, Flues, Boilers or Unfired Steam Pressure Vessels. See Appendix B.

(4) General Industry Safety Order 3518: Air Compressors. See Appendix B.

(c) Compressed gases shall not be used to elevate or otherwise transfer any substance from or to a container unless the container(s) is/are designed to withstand the maximum possible pressure that my be applied with a factor of safety of at least 4.

Compressed gases shall not be used for pressure testing of any object until a safe pressure and procedure have been established.

Except where pressure tested in accordance with (d), elastic materials must not be gas tested at pressure above 67% of the minimum specified yield point at test temperature. Brittle materials must not be gas tested above 40% of the minimum specified ultimate strength without remote operation and missile shielding. "Brittle Material" is defined for this section as having a minimum specified elongation of 4% or less.

(d) Hydrostatic or Pneumatic Testing (subchapters 1 and 2) of Pressure Vessels, and included piping of 2" diameter.

(1) The rules of applicable Codes or Standards shall be used for hydrostatic, pneumatic or combination hydrostatic-pneumatic testing. Proof tests and tests to failure must also use procedures allowed by applicable codes or standards. If no applicable code or standard exists, the test procedure must be reviewed and accepted by the Division.

(2) All valves, fittings and flanges used for pressure testing equipment, for either new construction or repair, shall have a minimum pressure rating equal to the test pressure. Use of an applicable ANSI standard pressure-temperature table such as in ANSI B16.5, is acceptable to determine the pressure rating.

(3) Except as allowed in (4), all temporary closures shall be threaded flanged with full bolting, or attached with full penetration welds; welded temporary closures must be so placed to preclude distortion or damage to the vessel or piping being tested.

Threaded connections shall conform to the following table:


(a)  Pressures up to and including 300 psi
Size of pipe connection, in......  1 & 1 1/4          1 1/2 & 2         2 1/2 to 4        4 1/2 to 6        7 & 8        9 & 10      12
Threads engaged ....................  4                   5                 7                  8              10           12        13
Min. plate thickness required, in..  0.348             0.435               0.875              1.0            1.25         1.5      1.625

(b)  Pressures above 300 psi
Size of pipe connection, in. ..... 1/2 & 3/4          1 to 1 1/2            2             2 1/2 to 3        4 to 6         10         12
Threads engaged .....................  6                  7                 8                  8              10           13         14
Min. plate thickness required, in... 0.43               0.61               0.70               1.0            1.25         1.62       1.75

(4) The use of expansion plugs or serrated plugs without through stays is limited to 6" nominal pipe size and/or 150 psi; for use of such devices above these limits specific written test procedures must be developed by the employer to protect against injury in the event the plug blows out.

Such instructions may include applicable data and recommendations furnished by the plug manufacturer and must include the following as a minimum:

(A) Identification by function of the personnel responsible for the various procedures.

(B) The test plugs must be well maintained and inspected by the designated employee before use.

(C) Any opening to be plugged shall satisfy any limitation on straightness, roundness and diameter and shall be cleaned of dirt, mill scale or oil.

(D) The plug must be of the correct size and pressure rating, including any limitations on the test fluid or test temperature. It must be inserted for full length of engagement, in accordance with the plug manufacturer's instructions.

(E) The test piece must be so oriented to minimize probability of the plug striking personnel or equipment if the plug is ejected. All air must be vented from objects to be hydrostatically tested. Test plugs shall be barricaded or equipped with arresting devices when pneumatic pressure is used for testing.

(F) Provision shall be provided for safe egress. No one shall be allowed to stand in front of the test plug or in line of probable trajectory during test.

(G) No one shall be allowed to stand on top of the object being tested, or on a ladder to the test section until the test object is brought up to full test pressure, held at test pressure for at least ten minutes, and pressure is reduced to a predetermined safe level.

(H) Pressurization shall be stopped at intervals to check pressure gage(s) and position of test plug(s).

(I) The test pressure shall be reduced to zero before the plugs are loosened for removal.

(J) Damaged or expanded closure ends must be cut off.

(K) All repairs to test plugs shall follow the plug manufacturer's instructions.

(5) Pipe test machines are acceptable for use after they have been reviewed by the Division for safe operational procedures.

(6) Pressure during test must be controlled within 5% above the required test procedure. Protection against overpressure must be provided at 110% of the test pressure. A relief valve setting of 133% of the test pressure may be used, for elastic materials only, where calculations show that 133% of the test pressure will not exceed 90% of the specified minimum yield strength of the material. The discharge from the safety relief valve or rupture disc must be led full size to a safe place.

The requirement for a relief valve may be waived by a Qualified Pressure Vessel Safety Engineer or Certified Pressure Vessel Inspector if the only source of test pressure is a handpump.

(e) Railroad tank cars containing compressed gas may not be used for interrupted unloading into smaller containers, unless permitted by the Federal Department of Transportation. Provisions for such unloading shall conform to DOT regulations.

See Petroleum Safety Orders, Sections 6879, 6880 and 6881 for requirements covering transfer operations at sidings inside petroleum refineries and distribution plants.

(1) An adequate unloading facility must be provided, and provisions must be made to support the transfer hoses. The transfer attendant must not be required to haul the transfer hoses up or down the tank car ladder.

(2) A bulkhead must be provided to prevent pullaway of the transfer hoses and/or to prevent imposing piping loads on the tank car valves. The bulkhead must be designed to withstand a horizontal pull of at least 2,000 pounds in any direction unless other adequate protection is provided. The unloading connections shall be firmly secured to the bulkhead. Excess flow valves, check valves or equivalent devices shall be provided where pipe or hose size is reduced.

The Qualified Transfer Attendant shall be instructed in all phases of the transfer operation. The instructions shall include a prohibition against overfilling any tank. Note: All valves in the transfer system must be fully open in order for an excess flow valve to function, so internal valves or check valves should be used whenever possible. The tank car excess flow valves are located in the internal piping beneath the dome.

NOTE: Bonding and grounding of the tank car and transfer equipment may be required for compressed flammable cases by railroad leasing agreement or by the local fire official.

(3) Written notification shall be given the Division and the local fire official of each non-permanently equipped transfer site. In emergencies, verbal notice may be given followed by written confirmation. Each such site shall be located, with respect to the minimum distance tables as outlined in Section 501(c) for NH3 or Sections 475(a) and (b) for Flammable Compressed Gas. Sites for transfer of other compressed gases must be at least 50 feet from railroad main track or important buildings. The working areas must be kept clear of debris and all transfer equipment must be protected from physical damage. Transfer shall be done only during daylight hours unless the transfer area is equipped with a lighting system and which provides at least 5 foot candles of illumination at all points of operations.

(4) Vehicle and tank car wheels must be blocked during transfer. Tank car brakes must be set. Tank cars must not be left connected to hoses and/or pipelines except during the unloading operation and while the qualified transfer attendant is present and in charge, unless the tank car valves are closed and locked, hoses are depressurized and/or a hydrostatic relief valve is installed between shutoff valves.

Valves on vehicles must be closed and locked except during transfer. Where vehicular container valves cannot be locked closed, the filling hose(s) must be disconnected when the qualified attendant is not present.

(5) Transport tank trucks and towed vehicles may load into the tank cars if they are also equipped with pullaway protection, in addition to meeting the requirements of paragraphs (1) through (4). A brake interlock system that is acceptable to the Division, and is connected to the truck tank unloading hose connection, is considered as an adequate pullaway safeguard.

Personal protective devices and safety equipment which are required and used for stationary storage facilities must be provided. Fire extinguishers must be provided for flammable compressed gases and anhydrous ammonia as required by the applicable safety order.

Appendix A
Appendix B
Appendix C


1. New subsection (e) filed 5-6-77; effective thirtieth day thereafter (Register 77, No. 19). For prior history, see Register 76, No. 51.

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