Mass. Gen. Laws ch. 146 § 70
All hot water heating boilers, except boilers specified in section seven, when used for space heating or as a heat storage source when the primary fluid circulates only within the code containment vessel or for process heating, and their appurtenances, that come within the scope of the current section one, four or eight of the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code, hereinafter referred to as the ASME Code, shall be thoroughly inspected internally when construction permits at least once every three years and externally at least once a year.
Changes in the rules which affect the construction of new boilers shall take effect six months after their filing, in the same manner prescribed for steam boilers in section two. The board may, upon request, permit the application of such changes in rules to boilers manufactured or installed during said six months. When a person or a corporation desires to manufacture a special type of boiler, the design of which is not covered by the rules formulated by the board or by the current section one, four or eight of the ASME Code, specifications and drawings shall be submitted through the chief of inspections to the board which, if it approves, shall permit the construction thereof.
The first inspection for the installation of a boiler covered by this section may be made by either a district engineering inspector of the division or by an authorized insurance inspector. The first part of the inspection on steel field erected boilers shall be completed before the system is filled with the fluid to be heated.
Mass. Gen. Laws ch. 146, § 70