Steam and hot water boilers shall be equipped with listed or approved steam safety or pressure relief valves of appropriate discharge capacity and conforming with ASME requirements (ASME Boiler & Pressure Vessel Code, Section IV, Heating Boilers). A shut-off valve shall not be placed between the relief valve and the boiler or on discharge pipes between such valves and the atmosphere.
02-658 C.M.R. ch. 109, § 19