Minn. Stat. § 183.51
Subd. 1. Engineers, classes.
Engineers shall be divided into four classes:
Subd. 2. Applications.
Any individual who desires an engineer's license shall submit an application on a written or electronic form prescribed by the commissioner, at least 15 days before the requested exam date. The application permits the applicant to take the examination on one occasion within one year from the date the commissioner receives the application.
Subd. 2a. Examinations.
Each applicant for a license must pass an examination developed and administered by the commissioner. The examinations shall be of sufficient scope to establish the competency of the applicant to operate a boiler of the applicable license class and grade.
Subd. 3. High and low pressure boilers.
For the purposes of this section and section 183.50, high pressure boilers shall mean boilers operating at a steam or other vapor pressure in excess of 15 p.s.i.g., or a water or other liquid boiler in which the pressure exceeds 160 p.s.i.g. or a temperature of 250 degrees Fahrenheit. Low pressure boilers shall mean boilers operating at a steam or other vapor pressure of 15 p.s.i.g. or less, or a water or other liquid boiler in which the pressure does not exceed 160 p.s.i.g. or a temperature of 250 degrees Fahrenheit.
Subd. 4. Chief engineer, Grade A.
An individual seeking licensure as a chief engineer, Grade A, shall be at least 18 years of age and have experience which verifies that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of boilers, steam engines, and turbines and their appurtenances; and, before receiving a license, the applicant shall take and subscribe an oath attesting to at least five years actual experience in operating such boilers, including at least two years experience in operating such engines or turbines.
Subd. 5. Chief engineer, Grade B.
An individual seeking licensure as a chief engineer, Grade B, shall be at least 18 years of age and have habits and experience which justify the belief that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of boilers and their appurtenances; and, before receiving a license, the applicant shall take and subscribe an oath attesting to at least five years actual experience in operating those boilers.
Subd. 6. Chief engineer, Grade C.
An individual seeking licensure as a chief engineer, Grade C, shall be at least 18 years of age and have habits and experience which justify the belief that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of low pressure boilers and their appurtenances, and before receiving a license, the applicant shall take and subscribe an oath attesting to at least five years of actual experience in operating such boilers.
Subd. 7. First-class engineer, Grade A.
An individual seeking licensure as a first-class engineer, Grade A, shall be at least 18 years of age and have experience which verifies that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of boilers, engines, and turbines and their appurtenances of not more than 300 horsepower or to operate as a shift engineer in a plant of unlimited horsepower. Before receiving a license, the applicant shall take and subscribe an oath attesting to at least three years actual experience in operating such boilers, including at least two years experience in operating such engines or turbines.
Subd. 8. First-class engineer, Grade B.
An individual seeking licensure as a first-class engineer, Grade B, shall be at least 18 years of age and have habits and experience which justify the belief that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of boilers of not more than 300 horsepower or to operate as a shift engineer in a plant of unlimited horsepower. Before receiving a license the applicant shall take and subscribe an oath attesting to at least three years actual experience in operating such boilers.
Subd. 9. First-class engineer, Grade C.
An individual seeking licensure as a first-class engineer, Grade C, shall be at least 18 years of age and have habits and experience which justify the belief that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of low pressure boilers and their appurtenances of not more than 300 horsepower or to operate as a shift engineer in a low pressure plant of unlimited horsepower. Before receiving a license, the applicant shall take and subscribe an oath attesting to at least three years actual experience in operating such boilers.
Subd. 10. Second-class engineer, Grade A.
An individual seeking licensure as a second-class engineer, Grade A, shall be at least 18 years of age and have experience which verifies that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of boilers, engines, and turbines and their appurtenances of not more than 100 horsepower or to operate as a shift engineer in a plant of not more than 300 horsepower, or to assist the shift engineer, under direct supervision, in a plant of unlimited horsepower. Before receiving a license the applicant shall take and subscribe an oath attesting to at least one year of actual experience in operating such boilers, including at least one year of experience in operating such engines or turbines.
Subd. 11. Second-class engineer, Grade B.
An individual seeking licensure as a second-class engineer, Grade B, shall be at least 18 years of age and have habits and experience which justify the belief that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of boilers of not more than 100 horsepower or to operate as a shift engineer in a plant of not more than 300 horsepower or to assist the shift engineer, under direct supervision, in a plant of unlimited horsepower. Before receiving a license the applicant shall take and subscribe an oath attesting to at least one year of actual experience in operating such boilers.
Subd. 12. Second-class engineer, Grade C.
An individual seeking licensure as a second-class engineer, Grade C, shall be at least 18 years of age and have habits and experience which justify the belief that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of low pressure boilers and their appurtenances of not more than 100 horsepower or to operate as a shift engineer in a low pressure plant of not more than 300 horsepower, or to assist the shift engineer, under direct supervision, in a low pressure plant of unlimited horsepower. Before receiving a license, the applicant shall take and subscribe an oath attesting to at least one year of actual experience in operating such boilers.
Subd. 13. Special engineer.
An individual seeking licensure as a special engineer shall be at least 18 years of age and have habits and experience which justify the belief that the individual is competent to take charge of and be responsible for the safe operation and maintenance of all classes of boilers and their appurtenances of not more than 30 horsepower or to operate as a shift engineer in a plant of not more than 100 horsepower, or to serve as an apprentice in any plant under the direct supervision of the properly licensed engineer.
Subd. 14. Current boiler operators.
Any individual operating a boiler other than a steam boiler on or before April 15, 1982, shall be qualified for application for the applicable class license upon presentation of an affidavit furnished by an inspector and sworn to by the individual's employer or a chief engineer. The applicant must have at least the number of years of actual experience specified for the class of license requested and pass the appropriate examination.
Subd. 15. Rating horsepower.
For the purpose of rating boiler horsepower for engineer license classifications only: ten square feet of heating surface shall be considered equivalent to one boiler horsepower for conventional boilers and five square feet of heating surface equivalent to one boiler horsepower for steam coil type generators.