Section 81. As used in this section and in sections eighty-two to eighty-eight, inclusive, the following words shall have the following meanings:

''Apprentice pipefitter'', a person who is registered and is learning or working at the business of pipefitting under the direct supervision of a master or journeyman pipefitter.

''Apprentice sprinkler fitter'', any person other than a fire sprinkler contractor or a sprinkler fitter who is presently engaged in both learning and assisting in the work being performed on any sprinkler system, and who must be employed by a licensed fire sprinkler contractor.

''Bureau'', the bureau of pipefitters, refrigeration technicians, and sprinkler fitters, established by section ten A of chapter twenty-two.

''Fire protection sprinkler system'', a fire sprinkler system, for fire protection purposes, the work of the sprinkler fitter and apprentice shall consist of the installation, service, testing, maintenance and inspection of all fire protection and fire control systems, including both overhead and underground water mains, fire hydrants and hydrant mains, standpipes and hose connections to sprinkler systems, sprinkler tank heaters, air lines and thermal systems, hot water fire protection systems and standpipes connected to sprinkler systems.

''Fire protection sprinkler system contractor'', a person, firm, or organization that offers to undertake the execution of contracts, the preparation of technical drawings, sale, installation, alteration, modification, service, testing, inspection, maintenance, removal and repairing of any such system or any part of such system.

''Journeyman pipefitter'', any person who has completed an apprenticeship training program satisfactory to the bureau and who by himself or with other journeymen pipefitters or apprentice pipefitters performs any work in pipefitting subject to inspection under any law, ordinance, by-law, rule or regulation but does not employ other journeymen or master pipefitters.

''Journeyman refrigeration technician'', any person who has completed an apprenticeship training program satisfactory to the bureau, and who has successfully passed a refrigeration technician's examination, and who, by himself, or with other journeymen refrigeration technicians, or with refrigeration apprentices does any work in refrigeration subject to the provisions of this chapter.

''Master pipefitter'', a person having a regular place of business or who, by himself, or with other master pipefitters, journeymen pipefitters, or apprentice pipefitters, in his employ performs pipefitting work.

''Master refrigeration technician'', a person having a regular place of business, or who by himself or with other master refrigeration technicians, journeymen refrigeration technicians, or refrigeration apprentices in his employ performs refrigeration work.

''Pipefitting'', the installation, repair, replacement, maintenance or alteration of any apparatus for piping appliances, devices or accessories for heating systems having a rating greater than 700,000 British Thermal Units, including apparatus and piping for the general use of conveyance of steam and associated pumping equipment, vacuum and pneumatic systems, oil and petroleum products, ice making machinery, air conditioning equipment, piping systems used for the conveyance and storage of Category M liquids, as defined in ASME B31.3 Process Piping manual and high pressure systems over 150 pound-force per square inch gauge or hazardous industrial type gases used in processes, biopharma or semi-conductor manufacturing, but excluding sheet metal work, refrigeration systems, boilers and plumbing as defined under the rules and regulations of the board of state examiners of plumbers promulgated under sections 4 and 13 of chapter 142.

''Refrigeration'', the installation, repair, replacement, maintenance of any refrigerant containing part of any refrigerant system of a ten ton capacity, or greater.

''Refrigeration apprentice'', any registered person who is at least eighteen years of age and who is working at the business of refrigeration under the supervision of a master refrigeration technician or journeyman refrigeration technician.

''Registered'', a person registered according to the provisions of chapter seven hundred and seven of the acts of nineteen hundred and forty-one.

''Sprinkler fitter/journeyman sprinkler fitter'', any person who has completed an apprenticeship training program satisfactory to the bureau, is employed by a licensed fire protection sprinkler system contractor and who, individually or with other sprinkler fitters, performs any work in sprinkler fitting subject to inspection under any law, ordinance, by-law, rule or regulation, but does not employ other sprinkler fitters.

''Ton'', for the purpose of this chapter one ton of refrigeration shall be defined in conformance to section I subparagraph 6 of the Board of Boiler Rules, Form BLR 7, dated November twenty-two, nineteen hundred and sixty-three.