Wash. Rev. Code § 70.79.130
In addition to the deputy boiler inspectors authorized by RCW 70.79.120, the chief inspector shall, upon the request of any company authorized to insure against loss from explosion of boilers and unfired pressure vessels in this state, or upon the request of any company operating boilers or unfired pressure vessels in this state, issue to any inspectors of said company commissions as special inspectors, provided that each such inspector before receiving his or her commission shall satisfactorily pass the examination provided for in RCW 70.79.170, or, in lieu of such examination, shall hold a certificate of competency as an inspector of boilers and unfired pressure vessels for a state that has a standard of examination substantially equal to that of this state or a certificate as an inspector of boilers and unfired pressure vessels from the national board of boiler and pressure vessel inspectors. A commission as a special inspector for a company operating boilers or unfired pressure vessels in this state shall be issued only if, in addition to meeting the requirements stated herein, the inspector is continuously employed by the company for the purpose of making inspections of boilers or unfired pressure vessels used, or to be used, by such company.
RCW 70.79.130