BLOWOFF PIPING

On all stationary boilers, when the allowable working pressure exceeds 100 pounds per square inch, each bottom blowoff pipe must have two slow-opening valves, or one slow-opening valve and a quick-opening valve or a cock complying with Section VII of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code. The quick-opening valve, if used, must be located nearest the boiler. The bottom blowoff pipes of every traction and/or portable boiler must have at least one slow-or-quick-opening blowoff valve or cock conforming to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section VII requirement. Blowoff valves and cocks must be located in a convenient and accessible place, using extension valve stems if necessary to secure safe operation.