Louisiana Administrative Code › Title 55 - PUBLIC SAFETY › Part V - Fire Protection › Chapter 50 - Boiler Construction, Maintenance, Inspection and General Use › Subchapter C - Existing Installations- Power Boilers › Section V-5025 - Safety Valves

Current through Register Vol. 50, No. 6, June 20, 2024
A. The use of
				  weighted-lever safety valves or safety valves having either the seat or disk of
				  cast-iron are prohibited; valves of this type of construction shall be replaced
				  by direct, spring-loaded, pop-type valves that conform to the requirements of
				  ASME Code, Section I.
B. Each
				  boiler shall have at least one ASME/NB stamped and certified safety valve, and
				  if it has more than 500 square feet of water-heating surface, or an electric
				  power input of more than 1100 KW, it shall have two or more safety valves of
				  the same type.
C. The valve or
				  valves shall be connected to the boiler, independent of any other steam
				  connection and attached as close as possible to the boiler without unnecessary
				  intervening pipe or fittings. Where alteration is required to conform to this
				  requirement, owner or user shall be allowed reasonable time in which to
				  complete the work as permitted by the chief inspector.
D. No valves of any description shall be
				  placed between the safety valve and the boiler nor on the escape pipe, if used.
				  When an escape pipe is used, it shall be at least the full size of the safety
				  valve discharge and fitted with an open drain to prevent water lodging in the
				  upper part of the safety valve or in the escape pipe. When an elbow is placed
				  on a safety valve escape pipe, it shall be located close to the safety valve
				  outlet or the escape pipe shall be anchored and supported securely. All safety
				  discharges shall be so located or piped as to be carried clear from walkways or
				  platforms.
E. The safety valve
				  capacity of each boiler shall be such that the safety valve or valves will
				  discharge all the steam that can be generated by the boiler without allowing
				  the pressure to rise more than 6 percent above the highest pressure to which
				  any valve is set, and in no case to more than 6 percent above the maximum
				  allowable working pressure.
F. One
				  or more safety valves on every boiler shall be set at or below the maximum
				  allowable working pressure. The remaining valves may be set within a range of 3
				  percent above the maximum allowable working pressure, but the range of setting
				  of all the safety valves on a boiler shall not exceed 10 percent of the highest
				  pressure to which any valve is set.
G. When boilers of different maximum
				  allowable working pressures with minimum safety valve settings varying more
				  than 6 percent are so connected that steam can flow toward the lower pressure
				  units, the latter shall be protected by additional safety valve capacity, if
				  necessary, on the lower pressure side of the system. The additional safety
				  valve capacity shall be based upon the maximum amount of steam which can flow
				  into the lower pressure system.
H.
				  In those cases where the boiler is supplied with feed water directly from water
				  mains without the use of feeding apparatus (not to include return traps), no
				  safety valve shall be set at a pressure greater than 94 percent of the lowest
				  pressure obtained in the supply main feeding the boiler.
I. The relieving capacity of the safety
				  valves on any boiler shall be done by one of the three following methods and,
				  if found to be insufficient, additional valves shall be provided:
1. by making an 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 percent of the maximum allow-able
				  working pressure. This method should not be used on a boiler with a super
				  heater or reheater;
2. 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 Code, Section I;
3. by measuring the maximum amount of feed
				  water that can be evaporated. When either of the methods outlined in two or
				  three 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.