Massachusetts General Laws
Chapter 142 - Supervision of Plumbing
Section 18 - Construction, Installing, Relocating and Repairing Requirements; Capacity; Strength; Solder; Pressure

Section 18. No hot water tank shall be repaired, relocated or installed and connected, unless it meets the following construction requirements:—
A. The actual capacity of a hot water tank shall be within seven and one half per cent of the capacity stamped on the tank.
B. A hot water tank shall be so constructed by riveting, welding, or otherwise, as to withstand the stamped test pressure without visible permanent distortion, and be so designed as to have an ultimate strength sufficient to withstand a hydrostatic pressure twenty-five per cent higher than the stamped test pressure.
C. Solder which melts at a temperature below seven hundred degrees Fahrenheit shall not be used to hold the tank together, but may be used to make it water tight, cistern tanks excepted.
D. A hot water tank in which water is to be heated or stored under pressure greater than fifteen pounds per square inch shall have a stamped test pressure of not less than two hundred pounds per square inch.
E. The maximum working pressure at which a hot water tank may be installed shall not be greater than fifty per cent of the test pressure marked on the tank.

Structure Massachusetts General Laws