D.C. Mun. Regs. tit. 12, r. 12-E1024
Insert a new Section 1024 in the Mechanical Code to read as follows:
Maximum allowable working pressure. The maximum allowable working pressure of heating boilers shall be determined as follows:
Low pressure boiler. A radiator in which steam pressure is generated at a pressure of 15 pounds per square inch (psi) (103 kPa) or less shall be considered a low pressure boiler.
Manufacturer's specification and identification. The maximum allowable working pressure shall in no case exceed the pressure indicated by the manufacturer's identification stenciled or cast upon the boiler or upon a plate secured to it. In the absence of a manufacturer's identification stencil or plate, the maximum allowable working pressure shall not exceed that recommended in the manufacturer's specification or catalog.
Safe operating pressure. If, in the judgment of the code official or an insurance company inspector, a steam- heating boiler is not safe for operation at the pressure previously approved, the operating pressure shall be reduced to a pressure deemed safe by the code official or insurance company inspector, or proper repair shall be made, or the boiler shall be retired from service, as determined by the code official or insurance company inspector.
Safety valves. Each steam- heating boiler shall be provided with one or more safety valves with a total area of not less than 1 square inch (645 mm2) for each 5 square feet (0.46 m2) of grate area or equivalent if grates are not used. The steam-relieving capacity of the safety valve or valves on any boiler shall be sufficient to prevent the boiler pressure from rising to more than 5 pounds per square inch (psi) (34 kPa) above the maximum allowable working pressure of the boiler.
Capacity. If there is any doubt as to the capacity of the safety valve, an accumulation test shall be run. No safety valve shall be smaller than 3/4 inch (19 mm) in diameter nor larger than 4.5 inches (114 mm) in diameter.
Stop valve. No stop valve of any type shall be located between a boiler and its safety valve, nor in the safety valve discharge pipe.
Parts and equipment. Each steam- heating boiler shall be equipped with the following parts and equipment that shall meet the requirements of Sections 1024.3.1 through 1024.3.8, as applicable.
Steam pressure gauge. Each steam-heating boiler shall have a steam pressure gauge connected to the steam space of the boiler itself or on steam pipe near the boiler. The graduation of the steam gauge shall not have a range of less than 15 pounds per square inch (psi) (103 kPa) nor more than 30 pounds per square inch (psi) (207 kPa).
Water gauge glass. Each heating boiler shall have at least one water gauge glass with the lowest visible part above the heating surfaces in the primary combustion chamber. When, in the judgment of the code official or an insurance company inspector, the heating surfaces above the low-water line may be damaged by contact with high temperature gases, the water gauges shall be raised until the lowest visible part of the glass gauge is above the testing surface.
Gauge cocks. Each steam- heating boiler shall have two or more gauge cocks located within the visible length of the water gauge glass.
Exception: Steam- heating boilers provided with two water gauge glasses.
Steam stop valve. Heating boilers that can be closed off from the heating system by closing a steam stop valve shall be equipped with a check valve in the condensate return line, between the boiler and the system. Any part of a heating system that can be closed off from the remainder of the system by closing a steam stop valve, shall be provided with a check valve in the condensate return pipe from that part of the system.
Feed-water connections. Feed-water connections shall be independent of any water gauge connections. Where possible, feed-water connections shall be made to the condensate return pipe of the reservoir of the condensate return pump. There shall be a check valve in the feed-water line, close to the boiler.
Low-water cut -off of mechanically fired boilers. Each mechanically fired heating boiler shall be equipped with a low-water cut-off so located as to automatically cut off the fuel supply in case t he 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 heating boilers are connected to the same system, each boiler shall have independent low-water cut-offs, controls and gauges.
Low-water cut-off of electrically operated boilers. If a low-water fuel cut-off device is electrically operated, it shall be so connected that it will fail-safe in the "cut-off" position both when the electric current is switched off and upon loss of electric power supply.
Condensate return pump. Each condensate return pump shall be provided with an automatic water level control, set to maintain the water level between two gauge cocks.
Repairs or replacements. When repairs or replacement of parts or piping are made, or fittings or appliances are replaced or attached to a heating boiler, the rules applying to new installations shall be followed as nearly as practicable.
Safety valve replacement. When a safety valve is replaced the requirements of Section 1010 shall be met. No safety valve shall be smaller than 3/4 inch (19 mm) in diameter nor larger than 4.5 inches (114 mm) in diameter.
D.C. Mun. Regs. tit. 12, r. 12-E1024