Wash. Rev. Code § 70.54.080
Every person who shall apply, or cause to be applied to a steam boiler a higher pressure of steam than is allowed by law, or by any inspector, officer or person authorized to limit the same; every captain or other person having charge of the machinery or boiler in a steamboat used for the conveyance of passengers on the waters of this state, who, from ignorance or gross neglect, or for the purpose of increasing the speed of such boat, shall create or cause to be created an undue or unsafe pressure of steam; and every engineer or other person having charge of a steam boiler, steam engine or other apparatus for generating or employing steam, who shall wilfully or from ignorance or gross neglect, create or allow to be created such an undue quantity of steam as to burst the boiler, engine or apparatus, or cause any other accident, whereby human life is endangered, shall be guilty of a gross misdemeanor.
RCW 70.54.080
Boilers and unfired pressure vessels: Chapter 70.79 RCW.
Industrial safety and health: Chapter 43.22 RCW.