Scope and Application

(1) In accordance with the provisions of M.G.L. c. 146, § 2, the Board adopts the 2021 ASME Boiler and Pressure Vessel Code Section IV, Rules for Construction of Heating Boilers. (2) Requirements. 522 CMR 4.00 shall apply to Boilers exceeding three horsepower and restricted to the following services: (a) Steam Low Pressure/Heating Boilers having a minimum safety relief valve capacity greater than 200 pounds per hour for operation at pressures not exceeding 15 PSIG (100 kPa). (b) Hot Water Low Pressure/Heating Boilers and hot water supply Boilers having a minimum safety relief valve capacity greater than 200,000 Btu/hr for operation at pressures not exceeding 160 PSIG (1,100 kPa). (c) Hot Water Low Pressure/Heating Boilers and hot water supply Boilers having a minimum safety relief valve capacity greater than 200,000 Btu/hr for operation at temperatures not exceeding 250EF (120EC), at or near the Boiler outlet, except that when some of the wrought materials permitted by 2021 ASME Boiler and Pressure Vessel Code Section IV, Rules for Construction of Heating Boilers are used, a lower temperature is specified. (d) Potable water heaters and water storage tanks for operation at pressures not exceeding 160 PSIG (1,100 kPA) and water temperatures not exceeding 210EF (99EC). 522 CMR 4.01(2)(d) shall not apply to units in this category when none of the following limitations is exceeded: 1. Heat input of 200,000 Btu/hr; 2. A water temperature of 210EF (99EC); 3. A nominal water-containing capacity of 120 gallons, except that they shall be equipped with safety devices in accordance with the requirements of the 2021 ASME Boiler and Pressure Vessel Code Section IV, Rules for Construction of Heating Boilers paragraph HLW-100. The minimum safety valve relieving capacity for Low Pressure/Heating Boilers and other heat storage sources shall be determined in accordance with the 2021 ASME Boiler and Pressure Vessel Code Section IV, Rules for Construction of Heating Boilers.