(3) Inspection. A District Engineering Inspector shall perform the First Inspection of a Boiler or Pressure Vessel as required by M.G.L. c. 146, § 6.

1. (a) Boilers. All Boilers and their Appurtenances shall be thoroughly inspected externally and internally under the specifications of 522 CMR 2.00: Power Boilers and 4.00: Heating Boilers and Other Heat Storage Sources, except those specified in M.G.L. c. 146, § 7, which includes:

   1. 1. Boilers of railroad locomotives, motor vehicles or steam fire engines brought into the Commonwealth for temporary use in times of emergency;
   2. 2. Boilers used in private residences;
   3. 3. Boilers used for heating purposes which carry pressures not exceeding 15 pounds to the square inch and have less than four square feet of grate surface;
   4. 4. Boilers of not more than three horsepower;
   5. 5. Boilers under the jurisdiction of the United States; and
   6. 6. Boilers used exclusively for horticultural or agricultural purposes.

2. (b) Air Tanks. All Air Tanks and their Appurtenances, except those specified in M.G.L. c. 146, § 34, shall be thoroughly inspected externally or internally consistent with the specifications set forth in 522 CMR 7.00: Air Tanks at least once every two years when the following criteria are met:

   1. 1. design MAWP greater than 50 PSI; and
   2. 2. greater than six inches internal diameter; and
   3. 3. internal volume greater than one cubic foot.

3. (c) Massachusetts Tag Number.

   1. 1. Every Boiler, Pressure Vessel, and Refrigeration and Air Conditioning System which has been inspected by the Division shall be given a registration number upon a nonferrous metal tag authorized by the Board. The tag shall be held by nonferrous wire in a conspicuous place on the unit and no person, except a District Engineering Inspector, shall remove the tag.
   2. 2. Authorized Inspection Agencies shall be furnished tag numbers by the Chief for Refrigeration and Air Conditioning systems, or hot water Boiler systems. The Authorized Inspection Agencies shall furnish tags, authorized by the Board, upon which shall be the tag number. The tag shall be made of non-ferrous metal and attached in a conspicuous place on the unit.