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D.C. Municipal Regulations (Last Updated: September 13, 2017) |
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Title 12. CONSTRUCTION CODES SUPPLEMENT OF 2013 |
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SubTilte 12-E. MECHANICAL CODE SUPPLEMENT OF 2013 |
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Chapter 12-E10. BOILERS, WATER HEATERS AND PRESSURE VESSELS |
Section 12-E1023. PARTS AND EQUIPMENT FOR EXISTING POWER BOILER INSTALLATIONS
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Insert new Section 1023 in the Mechanical Code to read as follows:
1023.1 Fire-actuated fusible plugs. Where fire-actuated fusible plugs are used, they shall conform to the rules of the ASME Code for new construction.
1023.2 Water glass. Each steam boiler shall have at least one water glass, the lowest visible part of which shall be as required by the ASME Code for new construction.
1023.3 Gauge cocks. Each boiler with an allowable working pressure in excess of 15 pounds per square inch (psi) (103 kPa) shall have three or more gauge cocks located within the range of the visible length of the water glass, except when such boiler has two water glasses with independent connections to the boiler located on the same horizontal plane and not less than 2 feet (610 mm) apart.
1023.4 Outlet connections. No outlet connections shall be placed on the pipes connecting a water column to a boiler, except for connections for a damper regulator, a feed water regulator, a low water fuel cut-off, drains or a steam gauge. Each water column shall have a valved drain extended to within 6 inches (152 mm) of the floor.
1023.5 Steam gauges. Each steam boiler shall have a steam gauge connected to the steam space or to the steam connection to the water column. The steam gauge shall be connected to a siphon or equivalent device of sufficient capacity to keep the gauge tube filled with water and so arranged that the gauge cannot be shut off from the boiler except by a cock placed near the gauge and provided with a “T” or lever handle arranged to be parallel to the pipe in which it is located when the cock is open.
1023.6 Low-water cut-off. Each mechanically fired steam boiler shall be equipped with a low-water fuel cut-off so located as to automatically cut off the fuel supply when the water level falls below the top of the bottom nut of the water glass. Each cut-off shall have a drain extended to within 6 inches (152 mm) of the floor. When two or more mechanically-fired boilers are connected to the same system, each boiler shall have independent low-water cut-offs, controls, and gauges.
1023.7 Stop valve. Each steam outlet from a high-pressure boiler shall be fitted with a stop valve located as close as practicable to the boiler. This requirement shall not apply to safety-valve connections.
1023.8 Blow drains. When a stop valve is so located that water can accumulate, free blow drains shall be provided, the discharge of which shall be visible to the operator while manipulating the valve.
1023.9 Blow-off connection. Each boiler shall have a full-size blow-off connection, fitted with a valve or cock connected directly with the lowest water space practicable. When cocks are used, they shall be of the gland or guard type and suitable for the pressure allowed. Globe valves shall not be used for this purpose.
1023.9.1 Extra heavy blow-off pipe. When the maximum allowable working pressure exceeds 100 pounds per square inch (psi) (689 kPa), the blow-off shall be extra heavy from boiler to valve or valves, and shall extend full size without reducers or bushings. Blow-off piping shall be of black wrought iron or black steel and shall be extra heavy pipe. Galvanized pipe shall not be used for this purpose.
1023.9.2 Fittings. All fittings between the boiler and valve shall be steel or extra heavy fittings of bronze, brass or malleable iron. Replacement of pipe or fittings in the blow-off lines shall be installed in accordance with the ASME Code for new installations.
Exceptions:
- Low-pressure heating boilers bearing the ASME stamp that are trimmed by the manufacturer are exempt from the fittings material requirements.
- Low-pressure heating boilers rated less than 100 horsepower (74.6 kW) are exempt from the fittings material requirements.
1023.9.3 Extra heavy blow-off valves. When the maximum allowable working pressure exceeds 100 pounds per square inch (psi) (689 kPa), each bottom blow-off pipe shall be fitted with two valves or a valve and cock, such valves and cocks to be of the extra heavy type.
1023.9.4 Protection of blow-off pipe. A bottom blow-off pipe, when exposed to direct furnace heat, shall be protected by fire-brick or other heat-resisting material, arranged so as to allow the pipe to be inspected. An opening in the boiler setting for a blow-off pipe shall be arranged to provide for free expansion and contraction.
1023.10 Feed-water connections. The feed pipe of a steam boiler shall be provided with a check valve near the boiler and a valve or cock between the check valve and the boiler. When two or more boilers are fed from a common source, there shall also be a globe valve on the branch to each boiler, between the check valves and the main feed pipe. When a globe valve is used on a feed pipe, the inlet shall be under the disk from the valve. In all cases where the safety valve is set above 25 pounds per square inch (psi) (172 kPa), there shall be a second means of feeding water against the maximum approved working pressure of the boiler.
1023.11 Hydrostatic test. When a hydrostatic test is applied, test pressure shall not exceed 1 ½ times the maximum allowable working pressure of the boiler. During a hydrostatic test of a boiler, suitable provisions shall be made to attain the test pressure without using the compression screw of the safety valve spring.
1023.12 Repairs and replacements. Where repairs or replacements are made or fittings or appliances are renewed or attached to a boiler, they shall comply with the provisions of the ASME Code for new installations.
1023.13 Conditions not covered by these rules. Installation conditions of power boiler parts and equipment not specifically covered in Chapter 10 of the Mechanical Code shall be regulated as determined by the code official.