Mich. Comp. Laws § 339.5923

Sec. 923. Subject to civil service rules, the director shall employ deputy inspectors who are responsible to the chief inspector. The department may only appoint an individual who meets all of the following as a deputy inspector: (a) At the time of appointment, has at least 5 years of experience in the inspection, construction, maintenance, repair, or operation of high pressure boilers as a mechanical engineer, steam operating engineer, boilermaker, or boiler inspector. (b) Has passed the deputy inspector examination under section 927 or meets either of the following: (i) Holds a license or a certificate of competency as an inspector of boilers for a state that has a standard of examination substantially equal to the standard of this state, as determined by the board. (ii) Holds a license as an inspector of boilers issued by the National Board of Boiler and Pressure Vessel Inspectors.