(a) Steam Heating Boilers.      
        (1) Safety valves.                  (A) Each steam boiler shall have one or more safety valves, that are identified with applicable designator with the ASME Certification Mark of the spring pop type, adjusted and sealed to discharge at a pressure not to exceed 15 psig (103 kilopascals). Seals shall be attached in a manner to prevent the valve from being taken apart without breaking the seal. The safety valves shall be arranged so that they cannot be reset to relieve at a higher pressure than the MAWP of the boiler. A body drain connection below seat level shall be provided. For valves exceeding 2 1/2 inch nominal pipe size (65 mm), the drain hole or holes shall be tapped not less than 3/8 inch nominal pipe size (10 mm). For valves 2 1/2 inch nominal pipe size (65 mm) or less, the drain hole shall not be less than 1/4 inch (6 mm) in diameter.                   (B) Each safety valve 3/4 inch nominal pipe size (20 mm) or over, used on a steam boiler, shall have a substantial lifting device, which will positively lift the disk from its seat at least 1/16 inch (1.6 mm), when there is no pressure on the boiler. The seats and disks shall be of suitable material to resist corrosion.                   (C) No safety valve for a steam boiler shall be smaller than 1/2 inch nominal pipe size (15 mm). No safety valve shall be larger than 4 1/2 inches nominal pipe size (15 mm). The inlet opening shall have an inside diameter approximately equal to, or greater than, the seat diameter.                   (D) The minimum relieving capacity of valve or valves shall be governed by the capacity marking on the boiler.                   (E) The minimum valve capacity in pounds per hour shall be the greater of that determined by dividing the maximum Btu output at the boiler nozzle obtained by the firing of any fuel, for which the unit is installed by 1,000, or shall be determined on the basis of the pounds of steam generated per hour, per square foot of boiler heating surface as given in §65.615, Exhibit 7. For cast iron boilers, the minimum valve capacity shall be determined by the maximum output method. In every case, the safety valve capacity for each steam boiler shall be such that with the fuel burning equipment installed, and operated at maximum capacity, the pressure cannot rise more than 5psig (35 kilopascals) above the MAWP.                   (F) Safety valve piping. No valve shall be placed between the safety valve and the boiler or on the discharge pipe between the safety valve and the atmosphere. When a discharge pipe is used, it shall be full size and fitted with an open drain to prevent water from lodging in the upper part of the safety valve or pressure relief valve or in the discharge pipe. When an elbow is placed on the safety valve discharge pipe, it shall be located close to the valve outlet. The discharge pipe shall be securely anchored and supported, independent of the valve. If a muffler is used on a pressure relief valve, it shall have sufficient area to prevent back pressure from interfering with the proper operation and discharge capacity of the valve.                   (G) Safety valves and pressure relief valves shall be installed on the boiler with spindles positioned vertically. The opening or connection between the boiler and any safety valve or pressure relief valve shall have at least the area of the valve inlet.         
        (2) Feedwater connections.                  (A) Feedwater or water treatment shall be introduced into a boiler through the return piping system or through an independent feedwater connection which does not discharge against parts of the boiler exposed to direct radiant heat from the fire. Feedwater or water treatment shall not be introduced through openings or connections provided for inspection or cleaning, safety valve, surface blowoff, water column, water gage glass, pressure gage, or temperature gage.                   (B) Feedwater pipe shall be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler or return pipe system.         
        (3) Low-water fuel cutoffs and water feeding devices.                  (A) All automatically fired steam boilers, except boilers having a constant attendant, who has no other duties while the boiler is in operation, shall be equipped with approved automatic low-water fuel cutoffs installed in such a manner that they cannot be rendered inoperative by the manipulation of any manual control or regulating apparatus.                   (B) The MAWP of all low water fuel cutoff devices shall be set at or above the boiler stamped MAWP.                   (C) When low-water fuel cutoff and feedwater pump controls are combined in a single device, an additional separate low-water fuel cutoff shall be installed. The additional control shall be wired in series electrically with the existing low-water fuel cutoff.                   (D) When a low-water fuel cutoff is housed in either the water column or a separate chamber, it shall be provided with a blowdown pipe and valve, not less than 3/4 inch nominal pipe size (20 mm). The arrangement shall be such that when the water column is blown down, the water level in it will be lowered sufficiently to activate the low-water fuel cutoff device.                   (E) If a water feed device is utilized, it shall be constructed to prevent feedwater from entering the boiler through the water column or separate chamber of the low-water fuel cutoff.         
        (4) Pressure gages.                  (A) Each steam heating boiler shall have a pressure gage connected to the device exterior to the boiler. The gage shall be of sufficient capacity to keep the gage tube filled with water and arranged so that the gage cannot be shut off from the boiler except by a cock with tee or lever handle placed in a pipe near the gage. The handle of the cock shall be parallel to the pipe in which it is located when the cock is open.                   (B) The scale on the dial of a steam heating boiler pressure gage shall be graduated to not less than 30 psig (207kilopascals) nor more than 60 psig (414 kilopascals). The travel of the pointer from zero to 30 psig (207 kilopascals) pressure shall be at least three inches.         
        (5) Stop valves.                  (A) Single steam heating boilers. When a stop valve is used in the supply pipe connection of a single steam heating boiler, there shall be one used in the return pipe connection.                   (B) Supply and return line. Each supply and return line to a steam heating boiler, which may be entered while adjacent boilers are in operation, shall be fitted with either two stop valves with ample drain between or a stop valve and figure 8 blank. The blank shall be installed between the stop valve and the boiler.                   (C) Type of stop valve. When stop valves over two inches in size are used, they shall be of the outside screw-and-yoke rising stem type or of such other type as to indicate at a distance whether it is closed or open by the position of its stem or other operating mechanism. The wheel may be carried either on the yoke or attached to the stem. If the valve is of the plug cock type, it shall be fitted with a slow opening mechanism and an indicating device and the plug shall be held in place by a guard or gland.         
        (6) Bottom blowdown or drain valve.                  (A) Bottom blowoff valve. Each steam heating boiler shall have a bottom blowoff connection fitted with a valve or cock, connected to the lowest water space practicable with a minimum size as shown in §65.615, Exhibit 8. The discharge piping shall be full size to the point of discharge. Boilers having a capacity of 25 gallons (95 liters) or less are exempt from these requirements.                   (B) Drain valve. Each boiler shall have one or more drain connections, fitted with valves or cocks connecting to the lowest water containing spaces. The minimum size of the drain piping, valves, and cocks shall be 3/4 inch nominal pipe size (20 mm). The discharge piping shall be full size to the point of discharge. When the blowoff connection is located at the lowest water containing space, a separate drain connection is not required.                   (C) Minimum pressure rating. The minimum pressure rating of valves and cocks used for blowoff or drain purposes shall be at least equal to the pressure stamped on the boiler, but in no case less than 30 psig (207 kilopascals). The temperature rating of such valves and cocks shall not be less than 250 degrees Fahrenheit (121 degrees Celsius).         
        (7) Water gage glasses.                  (A) Each steam heating boiler shall have one or more water gage glasses attached to the water column or boiler, by means of valved fittings not less than 1/2 inch nominal pipe size (15 mm). The lower fitting shall have a drain valve of the straightway type, with opening not less than 1/4 inch (8 mm) diameter to facilitate cleaning. Gage glass replacement shall be possible under pressure.                   (B) Transparent material, other than glass, may be used for the water gage, provided that the material will remain transparent and has proved suitable for the pressure, temperature, and corrosive conditions encountered in service.         
        (8) Piping, Fittings and Valves.                  (A) All piping, fittings and valves on the steam line, shall have a pressure rating equal to or greater than the MAWP of the boiler and a temperature rating of no less than 250 degrees Fahrenheit (121 degrees Celsius).                   (B) All piping, fittings and valves other than the steam line, shall have a minimum pressure and temperature rating equal to or greater than the maximum expected pressure and temperature that may be reached.         
      (b) Hot Water Heating Boilers.      
        (1) Pressure relief valves.                  (A) Each hot water heating boiler shall have at least one pressure relief valve, of the automatic reseating type, identified with the ASME Certification mark with the "V" or "HV" designator ASME Code Symbol, and set to relieve at or below the MAWP of the boiler.                   (B) When more than one pressure relief valve is used on a hot water heating boiler, the additional valve or valves shall have a set pressure within a range not to exceed 6 psig (42 kilopascals) above the MAWP of the boiler up to and including 60 psig (414 kilopascals), and 5.0% for those having a MAWP exceeding 60 psig (414 kilopascals).                   (C) Pressure relief valves shall be spring loaded and shall be set and sealed, so that they cannot be reset without breaking the seal. A body drain connection below seat level shall be provided. For valves exceeding 2 1/2 inch nominal pipe size (65 mm), the drain hole or holes shall be tapped not less than 3/8 inch nominal pipe size (10 mm). For valves of 2 1/2 inch nominal pipe size (65 mm) or less, the drain hole shall not be less than 1/4 inch (6 mm) diameter.                   (D) Each pressure relief valve shall have a substantial lifting device, which will positively lift the disk from its seat at least 1/16 inch (1.6 mm) when there is no pressure on the boiler.                   (E) Seats and disks of pressure relief valves shall be made of a suitable material to resist corrosion. No materials likely to fail due to deterioration or vulcanization, when subjected to saturated steam temperature corresponding to capacity test pressure, shall be used for any part.                   (F) No pressure relief valve shall be smaller than 3/4 inch nominal pipe size (20 mm) nor larger than 4 1/2 inch nominal pipe size (115 mm) except that boilers having a heat input not greater than 15,000 Btu/hr (4.4 kilowatts) may be equipped with a rated pressure relief valve of 1/2 inch nominal pipe size (15 mm). The inlet opening shall have an inside diameter approximately equal to, or greater than, the seat diameter. In no case shall the minimum opening through any part of the valve be less than 1/4 inch (6 mm) diameter or its equivalent area.                   (G) The required steam relieving capacity, in pounds per hour, of the pressure relieving device or devices on a boiler shall be the greater of that determined by dividing the maximum output in Btu at the boiler nozzle obtained by the firing of any fuel for which the unit is installed by 1,000 or shall be determined on the basis of pounds of steam generated per hour per square foot of boiler heating surface as given in §65.615, Exhibit 7. For cast iron boilers the minimum valve capacity shall be determined by the maximum output method.                   (H) In every case, the pressure relief valve capacity for each boiler with a single pressure relief valve shall be such that, with the fuel burning equipment installed and operated at maximum capacity, the pressure cannot rise more than 10% above the MAWP. When more than one pressure relief valve is used, the overpressure shall be limited to 10% above the set pressure of the highest set valve.                   (I) Pressure relief valve piping. No valve shall be placed between the pressure relief valve and the boiler or on the discharge pipe between the pressure relief valve and the drain. When a discharge pipe is used, it shall be full size and fitted with an open drain to prevent water from lodging in the upper part of the pressure relief valve or in the discharge pipe. When an elbow is placed on the pressure relief valve discharge pipe, it shall be located close to the valve outlet. The discharge pipe shall be securely anchored and supported, independent of the valve. Mufflers shall not be used on hot water heating boilers.                   (J) Pressure relief valves and safety valves shall be installed on the boiler with spindles positioned vertically. The opening or connection between the boiler and any pressure relief valve or safety valve shall have at least the area of the valve inlet.         
        (2) Makeup water connections.                 Cont'd...