A. Automatic Low Water Fuel Cutoff or Water Feeding Device.
(1) An automatically fired steam or vapor system boiler shall have a low water fuel cutoff that automatically cuts off the fuel supply when the water surface falls to the lowest safe level. The following apply:
(a) A water feeding device shall be:
(i) Constructed so that the water inlet valve cannot feed water into the boiler through the float chamber, and
(ii) Located to supply the necessary feedwater;
(b) The lowest safe water line shall be not lower than the lowest visible part of the water glass.
(2) A fuel or feedwater control device may be attached:
(a) Directly to a boiler; or
(b) To the tapped openings provided to attach a water glass directly to a boiler, provided that for low-pressure boilers:
(i) Connections from the boiler are made with nonferrous tees or Y's at least 1/2 inch pipe size between the boiler and the water glass, so that the water glass is attached directly and as close as possible to the boiler,
(ii) Straightaway tapping of the Y or tee takes the water glass fittings, and
(iii) The side outlet of the Y or tee takes the fuel cutoff or water feeding device.
(3) The ends of all nipples shall be reamed to full-size diameter.
(4) A design using a float and float bowl shall have a vertical straightway valve drain pipe located at the lowest point in the water-equalizing pipe connections by which the bowl and equalizing pipe can be flushed and the device tested.
B. Blowoff Equipment.
(1) Blowdown from a boiler that enters a sanitary sewer system, or blowdown that is a hazard to life or property, shall pass through blowoff equipment to ensure that the maximum:
(a) Temperature of water leaving the equipment is 150°F; and
(b) Pressure of blowdown leaving the equipment is 5 PSIG.
(2 Blowoff equipment shall:
(a) Use piping and fittings between the boiler and the blowoff tank that comply with the ASME Code, Section I, paragraph PG-59;
(b) Be fabricated of material that complies with the ASME Code, Section II;
(c) Be fitted with openings that facilitate cleaning and inspection; and
(d) Conform to the rules for boiler blowoff equipment established by the National Board.
C. Discharge of safety valves, blowoff pipes, and other outlets shall be located to prevent injury to personnel.
D. Boiler-Door Latches.
(1) Firing Doors.
(a) The firing doors on a watertube boiler shall:
(i) Open inward; (
(ii) Be equipped with effective fastening devices; or
(iii) Be constructed to prevent the doors from being blown open by pressure on the furnace side.
(b) Except for coal openings on a downdraft or similar furnace:
(i) Door fastenings shall be positive self-locking; and
(ii) Friction contacts, latches, or bolts actuated by springs may not be used.
(2) An explosion door, if used and located in a setting wall within 7 feet of a firing floor or operating platform, shall have substantial deflectors to divert a blast.
(3) Except for an explosion door, a door not used during boiler firing may be equipped with bolts or fastenings.
E. Pressure-Reducing Valve.
(1) When a pressure-reducing valve is used:
(a) If the piping or equipment on the low-pressure side of the reducing valve does not meet the requirements for full initial pressure, at least one relief or safety valve shall be installed on the low-pressure side of the reducing valve;
(b) The relief or safety valves shall adjoin or be as close as possible to the reducing valve;
(c) When a relief or safety valve is vented to the atmosphere, proper protection shall be provided to prevent escaping fluid from causing injury or damage;
(d) The combined discharge capacity of relief or safety valves shall be such that the pressure rating of the lowest pressure piping or equipment cannot be exceeded if the reducing valve sticks open.
(2) Bypass Around Reducing Valves.
(a) A hand-controlled bypass around a reducing valve may be used.
(b) If a bypass is used around a reducing valve, the safety valve on the low-pressure side shall have sufficient relief capacity to prevent overpressuring the low-pressure side.
(3 ) A pressure gage shall be installed on the low-pressure side of a reducing valve.
F. A boiler or pressure vessel shall have masonry or structural supports of sufficient strength and rigidity to:
(1) Safely support the boiler or pressure vessel and its contents; and
(2) Prevent excessive vibration of the boiler, pressure vessel, or connecting piping.