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Virginia Administrative Code (Last Updated: January 10, 2017) |
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Title 16. Labor and Employment |
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Agency 25. Safety and Health Codes Board |
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Chapter 50. Boiler and Pressure Vessel Regulations |
Section 450. Pressure-reducing valves
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A. Where pressure-reducing valves are used, one or more relief or safety valves shall be provided on the low-pressure side of the reducing valve when the piping or equipment on the low-pressure side does not meet the requirements for the full initial pressure. Proper protection shall be provided to prevent injury or damage caused by the escaping fluid from the discharge of relief or safety valves if vented to the atmosphere. The combined discharge capacity of the relief or safety valves shall be such that the pressure rating of the lower pressure piping or equipment shall not be exceeded in case the reducing valve sticks open.
B. The use of hand-controlled bypasses around reducing valves is permissible. If a bypass is used around the reducing valve, the safety valve required on the low pressure side shall be sufficient capacity to relieve all the fluid that can pass through the bypass without overpressuring the low pressure side.
C. A pressure gauge shall be installed on the low-pressure side of a reducing valve.
Historical Notes
Derived from VR425-01-75 § 4.7, eff. July 1, 1974; amended, eff. November 1, 1978; July 1, 1991; September 1, 1993.