Changes in the rules which affect the construction of new boilers shall take effect six months after their filing as provided in section two; provided, that the board may, upon request, permit the application of such change in rules to boilers manufactured or installed during said six months. When a person desires to manufacture a special type of boiler the design of which is not covered by the rules formulated by the board, he shall submit drawings and specifications of such boiler to said board, which, if it approves, shall permit the construction thereof.
Massachusetts Legal Code