The relieving capacity of the safety valves on any boiler shall be checked by 1
of the following methods and, if found to be insufficient, additional valves
shall be provided:
(a) By making the
accumulation test, which consists of shutting off all other steam discharge
outlets from the boiler and forcing the fires to the maximum. The safety valve
capacity shall be sufficient to prevent a rise of pressure in excess of 6% of
the maximum allowable working pressure. This method should not be used on a
boiler with a superheater or reheater.
(b) By measuring the maximum amount of fuel
that can be burned and computing the corresponding evaporative capacity (steam
generating capacity) upon the basis of the heating value of this fuel. These
computations shall be made as outlined in the appendix of the ASME power boiler
(c) By measuring the maximum
amount of feedwater that can be evaporated.
(2) When either of the methods outlined in
subrule (1) (b) or (c) is employed, the sum of the safety valve capacities
shall be equal to or greater than the maximum evaporative capacity (maximum
steam generating capacity) of the boiler.