Sec.29-232-92. Installation of safety and relief valves

(a) Safety valves shall be located in the top or side of boilers, with the spindle vertical, but in no case shall the valves be located below the lowest permissible water level. They shall be connected directly to a tapped or flanged opening in the boiler, to a fitting connected to the boiler by a close nipple, to a Y base, or to a valveless header connecting steam outlets on the same boiler.

(b) Relief valves shall be located in the top or side of boilers, with the spindle vertical, but in no case shall the valves be located below the lowest permissible water level. They shall be connected directly to a tapped or flanged opening in the boiler, to a fitting connected to the boiler by a close nipple, to a Y base, or to a valveless header connecting water outlets on the same boiler.

(c) When a Y base is used, the inlet area shall be not less than the combined outlet areas. When the size of the boiler requires a safety valve or relief valve larger than four and one-half inches in diameter, two or more valves having the required combined capacity shall be used. When two or more valves are used on a boiler, they may be single, directly attached, or mounted on a Y base.

(d) No shut-off of any description shall be placed between the safety or relief valve and the boiler, nor on discharge pipes between such valves and the atmosphere. Safety and relief valves shall not be connected to an internal piping in the boiler.

(e) When a discharge pipe is used, its area shall be not less than the area of the valve or aggregate area based on the nominal diameters of the valves with which it connects, and the discharge pipe shall be fitted with an open drain to prevent water from lodging in the upper part of the valve or in the pipe. When an elbow is placed on a safety or relief valve discharge pipe, it shall be located close to the valve outlet. If the discharge is piped outside, a tee shall be installed in the discharge line inside the building with at least a ten inch long nipple turned up so as to relieve the drain line pressure in case of outside stoppage. The pipe shall be supported so that no undue stress is placed on the valve body. The discharge from safety or relief valves shall be so arranged that there will be no danger of scalding attendants.

(Effective August 25, 1987)