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Subchapter 14. Petroleum Safety Orders--Drilling and Production
Article 38. Pumps and Pump Pressure Relief Devices
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§6634. Pumps and Pump Pressure Relief Devices.

(a) Pumps shall not be operated in excess of manufacturer's allowable rated working pressure.

Every power driven piston or plunger type pump shall have a maximum allowable rated working pressure of the pump shown in raised or stamped letters and figures on a metal plate affixed to the pump where readily visible. The letters and figures shall be so maintained as to be legible.

(b) All positive displacement pumps shall be equipped with a pressure relief device.

(c) Pressure relief devices shall be installed and maintained as follows:

(1) There shall be no intervening stop valves between the pump and its pressure-relief device nor between the pressure-relief device and the point of discharge which would render the pressure relief device ineffective.

EXCEPTION: The pump may have a valve between it and its pressure relief device for use during repair, in which case the valve shall be locked or sealed open and shall not be closed except by a qualified person assigned such duties by the employer, and such person shall immediately replace the relief device and again lock or seal the valve in the open position before leaving the location.

(2) The pressure relief device shall be so installed and maintained to ensure its operation.

(3) The point of discharge from pressure relief devices shall be at a place where the safety of employees is not endangered by the discharged liquids.

(4) Pressure relief devices shall be set to relieve at a pressure not in excess of ten percent (10%) above the maximum allowable rated working pressure of the pump.

(d) Every shear-pin-set relief valve shall have a metal plate attached to it with holes drilled as a gage for each size shear pin to be used with the valve and a table with stamped or raised letters and figures, showing the pressure at which each size shear pin will shear. The shear pin shall be in accordance with the manufacturer's recommendation as to size, type and installation.

(e) Every shear-pin-set relief valve shall have the valve stem and the shear pin enclosed in a manner that will prevent contact with the valve stem and also prevent the shear pin flying when sheared.

(f) Each disk used in a rupture type pressure relief device shall have stamped on it the approximate pressure at which it will rupture.

(g) Adequate drainage shall be provided to prevent the accumulation of oils or drilling fluids around pump bases.

(h) Stuffing boxes of pumps handling flammable liquids shall be maintained so as to prevent excessive leakage.

(i) Pumps handling flammable liquids, corrosives, or any fluid at a temperature over one hundred fifty degrees (150o) Fahrenheit shall be equipped with shields or covers to protect employees from the hazard of liquid spray if the service experience of the pump indicates that the stuffing box or type packing used is inadequate to prevent a liquid spray hazardous to employees.

(j) No pump shall be set in motion when the fluid end cylinder head is not secured in place unless precautions are taken to prevent injury to employees.

(k) The use of hydraulic, pneumatic or gas pressure inside a pump to remove pump liners is prohibited. This does not prohibit the use of hydraulic or pneumatic tools made for this purpose.

(l) Every pump shall be equipped with a bleeder pipe and valve through which the pressure in any part of the pump can be bled off to atmospheric or as near atmospheric pressure as is practicable unless other piping and valves connected to the pump can be effectively used for this purpose.

(m) Before beginning the removal of any cap, plug, plate or cover from a pump or otherwise opening a pump the pressure within the pump shall be bled off to atmospheric or as near atmospheric pressure as is practicable.

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. Amendment filed 7-20-59; effective thirtieth day thereafter (Register 59, No. 12).

2. Amendment of article 38 heading, section heading, section and Note filed 5-8-95; operative 6-7-95 (Register 95, No. 19).

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