Code of Massachusetts Regulations
522 CMR - BOARD OF BOILER RULES
Title 522 CMR 7.00 - Air Tanks
Section 7.02 - Construction
Current through Register 1531, September 27, 2024
All Air Tanks under the scope of 522 CMR 7.00 shall be initially constructed in accordance with the 2019 ASME Boiler and Pressure Vessel Code Section VIII, Rules for Construction of Pressure Vessels.
(1) All tanks shall be available for complete External Inspection and shall be so installed that there will be not less than 12 inches between the tank and any floor, wall, ceiling or other obstruction, except where a tank is attached to a portable compressor by means of straps and is removable for complete inspection. The 12 inch clearance may be waived by the District Engineering Inspector. Tanks installed prior to October 1977 may have the 12 inch clearance waived by an Authorized Inspector or the District Engineering Inspector. The District Engineering Inspector shall document in their report that there was not a clearance of 12 inches but a complete External and Internal Inspection could be made. The name plate, safety valve, drain, pressure gauge, tank bottom, and inspection openings shall be readily visible and accessible if the clearance requirement is to be waived.
(2) In case of vertical tanks the bottom head if dished shall have the pressure on the concave side to ensure complete drainage.
(3) Vertical tanks with a base ring shall have unobstructed access to the tank bottom for inspection.
(4) Air tanks in a fixed installation shall be secured to prevent movement.
(5) Steel piping shall be used from the air tank outlet to the first block valve of the air distribution system.
(6) Air tanks that can be isolated with block valves shall have a pressure relief valve attached to the pressure vessel.
(7) Air tanks that can be isolated with block valves shall have a pressure gage attached to the pressure vessel per 522 CMR 7.00.
(8) The connection to the pressure relief valve shall be as short as possible and not reduced.
(9) The pressure relief valve shall discharge to a safe location.
(10) The pressure relief valve shall be sized to relieve the capacity of all compressors which may operate at one time.
(11) In systems with multiple tanks, all tanks shall have a safety relief valve which lifts at the pressure of that tank with the lowest MAWP or other means shall be provided to prevent pressurizing any tank to a pressure greater than that tank's MAWP.
(12) Tanks shall be protected from external corrosion.
(13) Automatic drains may be used in addition to the drain required by 522 CMR 7.00.
(14) All tanks shall be protected by such safety valves and indicating and controlling devices as will ensure their safe operation. These devices shall be so constructed, located, and installed that they cannot readily be rendered inoperative.
