Pressure reducing valves

1. Where pressure reducing valves are used, one or more relief or safety valves must be provided on the low-pressure side of the reducing valve in case the piping or equipment on the low-pressure side does not meet the requirements for the full initial pressure. The relief of safety valves must be located adjoining or as close as possible to the reducing valve. Proper protection must be provided to prevent injury or damage caused by the escaping steam from the discharge. Capacity of the relief valves must be such that the pressure rating of the lower pressure piping or equipment shall not be exceeded in case the reducing valve sticks open. 2. The use of hand-controlled bypasses around reducing valves is permissible. The bypass if used around a reducing valve may not be greater in capacity than the reducing valve unless the piping or equipment is adequately protected by relief valves or meets the requirements of the high-pressure system. 3. A pressure gauge must be installed on the low-pressure side of a reducing valve. 4. All low-pressure headers and their outlets must be protected by a safety valve or valves whose combined capacity is equivalent to the total amount of steam that can pass from the high-pressure system to the lower pressure system.