Section R. 339.5174 - Classes of boiler installer's licensesRule 174.
(1) A class 1B installers license qualifies an individual to install a low-pressure boiler that does not exceed a firing rate of 1,000,000 British thermal units (BTU) per hour as certified by the boiler manufacturer. For a class 1B license, the sum of all modules in a modular boiler must not exceed a firing rate of 1,000,000 BTU per hour as certified by the boiler manufacturer.(2) A class 2B installers license qualifies an individual to do both of the following:(a) Install a low-pressure boiler of any capacity or firing rate.(b) Perform work covered by a class 1B license.(3) A class 3B installers license qualifies an individual to do all the following: (a) Install a power boiler that has a capacity of not more than 5,000 pounds of steam per hour.(b) Install or replace non-boiler external piping as defined by the American Society of Mechanical Engineers (ASME), as defined in Subpart B Part 1, code B31.1, 2018, and R 339.5209.(c) Perform work covered by a class 2B license.(4) A class 4B installers license qualifies an individual to do all the following: (a) Install a power boiler that has a capacity of not more than 300,000 pounds of steam per hour.(b) Install or replace non-boiler external piping as defined by ASME code B31.1 and R 339.5209.(c) Perform work covered by a class 3B license.(5) A class 5B installers license qualifies an individual to do all of the following: (a) Install a power boiler of any capacity or firing rate, except for a nuclear heat source boiler.(b) Install or replace non-boiler external piping as defined by ASME code B31.1 and R 339.5209.(c) Perform work covered by a class 4B license.(6) A class 6B installers license qualifies an individual to install a boiler that utilizes a nuclear heat source or its parts, appurtenances, or system components. Before a license is issued, an individual who is applying for a class 6B license shall submit evidence of both of the following:(a) Familiarity with and knowledge of all federal rules and regulations regarding the installation of a boiler that has a nuclear heat source.(b) Employment by a company in possession of a valid ASME nuclear code symbol applicable to the portions of any nuclear boiler system that the company proposes to install.(7) A class P license qualifies an individual to install or replace non-boiler external piping or repair non-boiler external piping as defined by ASME code B31.1 and R 339.5209.Mich. Admin. Code R. 339.5174