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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-E1008. BOILER CONTROLS
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Strike Section 1008 of the International Mechanical Code in its entirety and insert new Section 1008 in the Mechanical Code in its place to read as follows:
1008.1 Steam limit control. Every steam boiler, when mechanically fired, shall be provided with a steam limit control (pressure regulator) that shall operate to prevent the steam pressure from rising above the allowable working pressure of the boiler. All connections shall be on non-ferrous pipe with screwed fittings. There shall not be any valve between the boiler and the control.
Exceptions:
- Boilers that bear the ASME stamp and are trimmed by the manufacturer are exempt from the non-ferrous pipe with screwed fittings requirement.
- Boilers rated less than 100 horsepower (74.6 kW) are exempt from the non-ferrous pipe with screwed fittings requirement.
1008.2 Master limit control. When two or more boilers are connected to a common header, a master limit control connected into the main steam header shall be provided to control all boilers simultaneously.
1008.3 Low-water fuel cut-off. Each steam boiler, when mechanically fired, shall be equipped with an approved low-water fuel cut-off, so arranged as to automatically cut off the fuel supply in case the water-level gauge indicates low-water level.
1008.4 Independent operational controls. The operation of automatic operational controls shall not be dependent upon the functioning of any other device.
1008.5 Oil burner cut-off location. When an oil burner is manually operated, the cut-off valve shall be located in the oil line close to the burner and shall only be re-set manually.
1008.6 Valve location restriction. No valves shall be permitted between the low-water fuel cut-off and the boiler.
1008.7 Water gauge glass controls. Each steam boiler shall have one or more water-gauge glasses attached to the water column or directly to the boiler by means of valved fittings, with the lower fitting provided with a drain valve of the straightway type with opening not less than 1/4 inch (6.4 mm) diameter. The gauge glasses shall be visible from the operating floor and without the removal of any cover or casing. There shall be no obstruction to interfere with visibility of the gauge glasses.
1008.8 Operating elevated gauge glass controls. When gauge cocks or gauge glass shut off cocks are located 78 inches (1981 mm) or more above the operating floor, they shall be of the quick opening type with chains or rods attached for operation from the floor. The gauge glass and pressure gauge shall be illuminated by a light with an approved type of reflector so that they can be easily read.
1008.9 Automatic water feeder. An automatic water feeder shall be installed on each mechanically fired steam heating boiler. It shall have sufficient capacity to take care of the water demand for maximum boiler output.
1008.10 Feed pump capacity. A boiler feed pump, when used, shall have capacity to supply sufficient water to all boilers served to maintain a normal water level when the boiler or boilers are operating at maximum capacity.
1008.11 Public water system by-pass. A public water system by-pass valve, with the valve accessible from the floor, shall be installed around a feeder and shall have a valved drain extended to within 6 inches (152 mm) of the floor. A mechanical water feeder supplied from a public water system shall be installed with a bypass valve, with inlet and outlet valves accessible from the floor, with cross tees for inspection and with the drain valve piping extended to within 6 inches (152 mm) of the floor.
1008.12 Feed-water level. A water feeder shall be installed so that it will not cause the water level to rise above the normal operating level specified by the manufacturer of the boiler.
1008.13 Minimum boiler water level. On low-pressure steam heating boilers, the water gauge glass shall be located so that the lowest permissible water level in the glass shall be as specified in Sections 1008.13.1 through 1008.13.4.
1008.13.1 Multiple fire-tube boilers. For multiple fire-tube boilers at least 1/2 inch (13 mm) of water shall be maintained over the top row of tubes or the fusible plug, if used, whichever is higher.
1008.13.2 Scotch Marine boilers. For package type Scotch Marine boilers at least 1/2 inch (13 mm) of water shall be maintained over the top row of tubes or the fusible plug, if used, whichever is higher.
1008.13.3 Horizontal tube boilers. For fire-box, horizontal water tube boilers at least 1 inch (25 mm) of water shall be maintained over the highest point of the crown sheet.
1008.13.4 Miscellaneous boilers. For any other type boiler the minimum water level shall be maintained in accordance with the manufacturer’s recommendations.
1008.14 Multiple boiler water level. Two or more boilers that share any appurtenance shall be arranged so that the low water lines of all boilers are at the same level.
Exception: When each boiler is provided with an individual pump control and an individual automatically operated feed water control valve, operation with different water levels shall be allowed.
1008.15 Boiler pressure gauge. Every boiler shall have a pressure gauge connected to its steam space, or to its water column, or to its steam connection by means of a siphon or equivalent device exterior to the boiler, and of sufficient capacity to keep the gauge tube filled with water. The pressure gauge shall be arranged so that the gauge cannot be shut off from the boiler except by a cock with a “tee” or lever handle installed in the pipe near the gauge.
1008.16 Cock handle position. The handle of the cock for the pressure gauge shall be parallel to the pipe in which it is located when the cock is open.
1008.17 Gauge scale graduation. The scale on the dial of a gauge on a low pressure boiler shall be graduated to not less than 30 pounds per square inch (psi) (210 kPa), in 5 psi (35 kPa) increments. Connections to steam gauge siphons shall be of non-ferrous pipe. The gauge shall be visible at all times without the removal of any cover or casing, and shall be of such size and so located as to be easily readable from the operating floor.
Exceptions:
- Boilers that bear the ASME stamp and are trimmed by the manufacturer are exempt from the non-ferrous pipe connection requirement.
- Boilers rated less than 100 horsepower (74.6 kW) are exempt from the non-ferrous pipe connection requirement.
1008.18 Independent controls. When two or more mechanically fired steam boilers are connected to the same system, each boiler shall have independent low-water fuel cut-offs, pressure controls, pressure gauges and water feeders.
1008.19 Non-ferrous pipe and fittings. All of the connections for the water column, water feeder, low-water fuel cut-off and make up water line to the boiler, shall be of non-ferrous pipe and screwed fittings, with a cross at each right angle turn and with a check valve in the feed line as close to the boiler as possible. High pressure boilers shall have a valve between the boiler and the check valve. Tubing shall not be permitted on boiler piping or fittings. All piping shall be firmly braced and supported.
Exceptions:
- Boilers that bear the ASME stamp and are trimmed by the manufacturer are exempt from the non-ferrous pipe with screwed fittings requirement.
- Boilers rated less than 100 horsepower (74.6 kW) are exempt from the non-ferrous pipe with screwed fittings requirement.
1008.20 Drain locations. Boiler drains shall be located so that the discharge will not impinge on the boiler setting or electrical equipment. Water column, water feeder and low-water fuel cut-off shall each have separate full size straight-way valve drains extended to within 6 inches (152 mm) from the floor or to a visible approved drain, with the valves located so as to be conveniently accessible for operation. Plug cocks shall not be used.