HAR §12-222.1-12. with the stop valve, or valves, required for the main discharge outlet on the boiler

(e) Blowoff. (1) Except for forced-flow steam generators with no fixed steam or water line, each boiler shall have a blowoff pipe, fitted with a stop valve, in direct connection with the lowest water space practicable. When the maximum allowable working pressure of the boiler exceeds one hundred (100) psig (700 kPa), there shall be two valves installed; (2) The blowoff piping for each electric boiler pressure vessel having a nominal water content not exceeding one hundred (100) gallons is required to extend through only one valve; (3) When two valves are required, each bottom blowoff pipe shall have two slow-opening valves, or one quick-opening valve, at the boiler nozzle followed by a slow-opening valve; (4) Two independent slow-opening valves, or a slow-opening valve and quick-opening valve, may be combined in one body provided the combined fitting is the equivalent of two independent slow-opening valves, or a slow-opening valve and a quick-opening valve, and the failure of one to operate cannot affect the operation of the other; (5) Straight-run globe valves or valves where dams or pockets can exist for the collection of sediment shall not be used; (6) The blowoff valve or valves and the pipe and fittings between them and the boiler shall be of the same size. The minimum size of pipe and fittings shall be NPS 1, except boilers with one hundred (100) square feet or less of heating surface should be NPS 3/4. The maximum size of pipe and fittings shall not exceed NPS 2-1/2; (7) For electric boilers, the minimum size of blowoff pipes and fittings shall be NPS 1, except for boilers of two hundred (200) kw 222.1-43 3559 §12-222.1-12 input or less where the minimum size should be NPS 3/4; (8) Fittings and valves shall comply with the appropriate national standard except that austenitic stainless steel and malleable iron are not permitted; (9) When the maximum allowable working pressure exceeds one hundred 100 psig, blowoff piping shall be at least Schedule 80 and the required valves and fittings shall be rated for at least 1.25 times the maximum allowable working pressure of the boiler. When the maximum allowable working pressure exceeds 900 psig, blowoff piping shall be at least Schedule 80 and the required valves and fittings shall be rated for at least the maximum allowable working pressure of the boiler plus 225 psi; (10) All blowoff piping, when exposed to furnace heat, shall be protected by fire brick or other heat resisting material so constructed that the piping may be readily inspected; (11) On a boiler having multiple blowoff pipes, a single master stop valve should be placed on the common blowoff pipe from the boiler and one stop valve on each individual blowoff. Either the master valve or the valves on the individual blowoff lines shall be of the slow-opening type; (12) The discharge of blowoff pipes shall be located so as to prevent injury to personnel; (13) All waterwalls or water screens that do not drain back into the boiler and integral economizers forming part of a boiler shall be equipped with blowoff piping and valves conforming to the requirements of this subsection; (14) Blowoff piping from a boiler should not discharge directly into a sewer. A blowoff tank, constructed to the provisions of a code of construction acceptable to the jurisdiction, shall be used where conditions do not provide an adequate and safe open discharge; 222.1-44 355 §12-222.1-12 (15) Galvanized pipe shall not be used; (16) Boiler blowoff systems should be constructed in accordance with the Guide for Blowoff Vessels (NB-27), which can be found on the National Board website at www.nationalboard.org; (17) Where necessary to install a blowoff tank underground, it shall be enclosed in a concrete or brick pit with a removable cover so that inspection of the entire shell and heads of the tank can be made; and (18) Piping connections used primarily for continuous operation, such as deconcentrators on continuous blowdown systems, are not classed as blowoffs; but the pipe connections and all fittings up to and including the first shutoff valve shall be equal at least to the pressure requirements for the lowest set pressure of any safety valve on the boiler drum and with the corresponding saturated-steam temperature. Further, such connections shall not exceed NPS 2-1/2. (f) Drains. Each boiler shall have at least one drainpipe fitted with a stop valve at the lowest point of the boiler. If the connection is not intended for blowoff purposes, a single valve is acceptable if it can be locked in the closed position or a blank flange can be installed downstream of the valve. If the connection is intended for blowoff purposes, requirements of (e) shall be followed. (1) For high temperature water boilers, the minimum size of the drainpipe shall be NPS 1; and (2) Drainpipes, valves, and fittings within the same drain line shall be the same size. (g) Electrical. A disconnecting means capable of being locked in the open position shall be installed at an accessible location at the boiler so that the boiler can be disconnected from all sources of potential. This disconnecting means shall be an integral part of the boiler or adjacent to it. (h) Wiring. All wiring for controls, heat generating apparatus, and other appurtenances necessary 222.1-45 3559