(a) General. The service restrictions and exceptions must be as indicated in this section in lieu of the requirements of HG-101 of Section IV of the ASME BPVC (incorporated by reference; see § 53.01-1).

(b) Service restrictions. (1) Boilers of wrought materials must be restricted to a maximum of 103 kPa gage (15 psig) for steam and a maximum of 689 kPa (100 psig) or 121 °C (250 °F) for hot water. If operating conditions exceed these limits, design and fabrications must be in accordance with part 52 of this subchapter.

(2) Boilers of cast iron materials must be restricted to a maximum of 103 kPa gage (15 psig) for steam and to a maximum of 206 kPa gage (30 psig) or 121 °C (250 °F) for hot water.

(c) Hot water supply boilers. (1) Electrically fired hot water supply boilers that have a capacity not greater than 454 liters (120 gallons), a heat input not greater than 58.6 kilowatts (200,000 Btu per hour), and are listed as approved under UL 174 or UL 1453 (both incorporated by reference; see § 53.01-1) are exempted from the requirements of this part provided they are protected by a pressure relief device. This relief device need not comply with § 53.05-2.

(2) Oil fired hot water supply boilers are not exempted from the requirements of this part on the basis of size or heat input.

(d) Exhaust gas boilers. Exhaust gas type boilers must be restricted to a working pressure equal to or less than 103 kPa gage (15 psig) and an operating temperature equal to or less than 454 °C (850 °F). The design temperature of parts exposed to the exhaust gas must be the maximum temperature that could normally be produced by the source of exhaust gas. This temperature must be verified by testing or by the manufacturer of the engine or other equipment producing the exhaust.

(e) ASME BPVC Section I. Heating boilers whose operating conditions are within the service restrictions of paragraph (b)(1) of this section may be constructed in accordance with Section I of the ASME BPVC (incorporated by reference; see § 53.01-1). In addition, these heating boilers must:

(1) Be stamped with the appropriate ASME symbol in accordance with Section I of the ASME BPVC;

(2) Meet the service restrictions of paragraph (b)(2) of this section if made of cast iron;

(3) Have safety valves which meet the requirements of § 52.01-120 of this subchapter;

(4) If a hot water supply boiler, have a temperature relief valve or a pressure-temperature relief valve in accordance with § 53.05-2(c);

(5) If automatically controlled, meet the applicable requirements in part 63 of this subchapter; and

(6) Meet the inspection and test requirements of § 53.10-3.

(f) Controls and miscellaneous accessories. Refer to part 63 of this subchapter for the requirements governing controls and miscellaneous accessories.