A. Blowoff Connection.
(1) A boiler shall have a blowoff pipe, fitted with a valve or cock, connected directly to the lowest water space. The following apply:
(a) A cock shall be of the gland or guard type, suitable for the pressure allowed;
(b) A globe valve may not be used.
(a) The setting around a blowoff pipe shall permit free expansion and contraction.
(b) To the maximum extent practicable, setting openings shall be sealed without restricting the movement of the blowoff piping.
(3) Blowoff piping exposed to furnace heat shall be:
(a) Protected by firebrick or other heat-resisting material; and
(b) Constructed so that the piping can be inspected readily.
(4) When the maximum allowable working pressure exceeds 100 PSIG:
(a) A blowoff pipe shall have two valves or a valve and cock of at least extra-heavy type;
(b) Blowoff piping shall:
(i) Be at least extra-heavy non-galvanized steel, and
(ii) Run full size without reducers or bushings.
(5) A fitting between the boiler and a blowoff valve shall be steel.
(6) A replacement blowoff pipe or fitting shall be installed in accordance with the ASME Code requirements for new installations.
B. Steam Gage.
(1) A steam boiler shall have a steam gage which:
(a) Has a dial range of at least 1-1/2 times the maximum allowable working pressure;
(b) Is connected to:
(i) The steam space or steam connection to the water column, and
(ii) A siphon or equivalent device of sufficient capacity to keep the gage tube filled with water;
(c) Is arranged so that the gage can be shut off from the boiler only by a cock with a tee or lever handle:
(i) Placed near the gage, and
(ii) With the handle parallel to the pipe in which it is located, when the cock is open.
(2) When a steam gage connection longer than 8 feet is necessary, a shutoff valve near the boiler may be used if the:
(a) Valve is:
(i) The outside-screw-and-yolk type, and
(ii) Locked open; and
(b) Line is:
(i) Of ample size, and
(ii) Permits free blowing.
(3) A boiler shall have a 1/4 inch nipple and globe valve:
(a) Connected to the steam space; and
(b) Used only to attach a test gage while the boiler is in operation, to measure the accuracy of the boiler steam gage.
C. Stop Valves.
(1) Except for safety valve and water column connections, each steam outlet from a boiler shall have a stop valve as near as practicable to the boiler.
(a) When a stop valve is located so water can accumulate, ample drains shall be provided.
(b) Drainage shall be piped to a safe location and may not be discharged on the top of the boiler or its setting.
(3) Common Steam Mains.
(a) When boilers having manholes are connected to a common steam main, the steam connection from each boiler shall be fitted with two stop valves having an ample free blow drain between them.
(b) The discharge of the drain shall be:
(i) Visible to the operator while manipulating the valves; and
(ii) Piped clear of the boiler setting.
(c) A stop valve arrangement having one automatic non-return valve beside the boiler, and a second valve of the outside-screw-and-yoke-type, is recommended.
D. Water Level Indicator.
(1) Except for a damper regulator, feedwater regulator, low-water fuel cutout, drain, steam gage, or other apparatus that does not permit the escape of an appreciable amount of steam or water, no outlet connection shall be placed on piping that connects a water column to a boiler.
(2) A water column shall have a valved drain of at least 3/4 inch pipe size.
(3) The drain shall be piped to a safe location.
(4) Gage Cocks.
(a) Except as otherwise provided by this regulation, a boiler shall have at least three gage cocks within the visible length of the water glass.
(b) A boiler shall have at least two gage cocks if the boiler:
(i) Has two water glasses on the same horizontal line; or
(ii) Is 36 inches or less in diameter, and has a heating surface of 100 square feet or less.
(5) When a water gage glass is more than 30 feet above the boiler operating floor, remote water-level indicating or recording gages installed above the operating floor at eye level are recommended.