The board shall formulate definitions and rules for the safe and proper construction, installation, repair, use, and operation of boilers and for the safe and proper construction, installation, and repair of unfired pressure vessels in this state. The definitions and rules so formulated shall be based upon, and, at all times, follow the nationally or internationally accepted engineering standards, formulae, and practices established and pertaining to boiler and unfired pressure vessel construction and safety, and the board may by resolution adopt existing published codifications thereof, and when so adopted the same shall be deemed incorporated into, and to constitute a part or the whole of the definitions and rules of the board. Amendments and interpretations to the code shall be enforceable immediately upon being adopted, to the end that the definitions and rules shall at all times follow nationally or internationally accepted engineering standards. However, all rules adopted by the board shall be adopted in compliance with the Administrative Procedure Act, chapter 34.05 RCW, as now or hereafter amended.