(a) Unfired steam boilers referred to in §65.2 are shown in §65.615, Exhibits 2 and 3.     
      (b) Unfired steam boilers shall be constructed in accordance with ASME Code, Section I, or ASME Code, Section VIII, Division 1, 2 or 3.      
        (1) Unfired steam boilers constructed to ASME Code, Section VIII, Division 1, 2 or 3, shall meet jurisdictional limits established in §65.615, Exhibit 2.       
        (2) Unfired steam boilers constructed to ASME Code, Section I, shall meet jurisdictional limits established in §65.615, Exhibit 3.       
      (c) Safety valves and pressure relief valves.      
        (1) The use of weighted-lever safety valves, or safety valves having either the seat or disk of cast iron, is prohibited.       
        (2) Each ASME Code, Section VIII, Division 1, 2 or 3, unfired steam boiler shall:                  (A) have all pressure relief valves fabricated in accordance with ASME Code, Section VIII, Division 1 or Section I; and                   (B) have at least one pressure relief valve.                   (C) Isolation valves may be installed between the unfired steam boiler and the safety valve in accordance with §65.615, Exhibit 2.                   (D) Full-area stop valves may be installed on the inlet side of a safety valve in accordance with §65.615, Exhibit 2. A full-area stop valve may be installed on the discharge of the safety valve when connected to a common header. Stop valves shall be car sealed or locked in the open position.                   (E) One or more safety valves on every unfired steam boiler shall be set at or below the MAWP. The remaining valves, if any, shall be set within the range specified and have the capacity required by the applicable section of the ASME Code.         
        (3) Each ASME Code, Section I, unfired steam boiler shall have one safety valve and if it has more than 500 square feet (47 square meters) of bare tube water heating surface, it shall have two or more safety valves.                  (A) The valve or valves shall be connected to the boiler, independent of any other steam connection, and attached as close as practicable to the boiler without unnecessary intervening pipe or fittings.                   (B) Valves, except a changeover valve as defined in §65.2(14), shall not be placed between the required safety valve or pressure relief valve or valves and the boiler nor on the discharge pipe between the safety valve or pressure relief valve and the atmosphere.                   (C) The safety valve capacity of each unfired steam boiler must allow the safety valve or valves to discharge all the steam that can be generated by the boiler without allowing the pressure to rise more than 6.0% above the highest pressure to which any valve is set, and to no more than 6.0% above the MAWP.         
        (4) When a discharge pipe open to the atmosphere is used, it shall be at least full size of the safety valve discharge and fitted with an open drain to prevent water lodging in the upper part of the safety valve or discharge piping. The drain or drains shall be piped to a safe point of discharge. When an elbow or fitting is installed on the discharge pipe it shall be located close to the safety valve outlet. The discharge pipe shall be securely anchored and supported. All safety valve discharges shall be located or piped to a safe point of discharge clear from walkways or platforms. 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.       
        (5) When two or more unfired steam boilers operating at different pressures and safety valve settings are interconnected, the lower pressure boilers or interconnected piping shall be equipped with safety valves of sufficient capacity to prevent overpressure, considering the maximum generating capacity of all boilers.       
        (6) Safety valve and pressure relief valve mountings.                  (A) For ASME Code, Section I installations, pressure relief valves shall be connected so as to stand in the upright position, with spindle vertical. The opening or connection between the boiler and the pressure relief valve shall have at least the area of the valve inlet.                   (B) For ASME Code, Section VIII, Division 1 installations, pressure relief valves normally should be installed in the upright position, with spindle vertical. Where space or piping configurations preclude such an installation, the valve may be installed in other than the vertical position, provided that:                      (i) the valve design is satisfactory for such position;                       (ii) the media is such that material will not accumulate at the inlet of the valve; and                       (iii) drainage of the discharge side of the valve body and discharge piping is adequate.           
      (d) Feedwater supply.      
        (1) Each unfired steam boiler shall have a feedwater supply which will permit it to be fed at any time while under pressure.       
        (2) Feedwater piping to the unfired steam boiler constructed to ASME Code, Section I, shall be provided with a check valve near the boiler and a stop 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 stop valve on the branch to each boiler between the check valve and the source of supply. Whenever a globe valve is used on the feedwater piping, the inlet shall be under the disk of the valve.       
        (3) Where deaerating heaters are not used, it is recommended that the temperature of the feedwater be not less than 120 degrees Fahrenheit (49 degrees Celsius), to avoid the possibility of setting up localized stress. Where deaerating heaters are used, it is recommended that the minimum feedwater temperature be not less than 215 degrees Fahrenheit (102 degrees Celsius), so that dissolved gases may be thoroughly released.       
      (e) Water level indicators.      
        (1) ASME Code, Section I, unfired steam boilers with a MAWP of 400 psig (three (3) megapascals) or less, shall have at least one gage glass. For a MAWP over 400 psig (three (3) megapascals), shall have two required gage glasses. When two gage glasses are required, one of the gage glasses may be replaced by two independent remote level indicators that are maintained in simultaneous operation while the boiler is in service.       
        (2) Each steam drum of an ASME Code, Section VIII, Division 1 unfired steam boiler, irrespective of pressure and temperature, shall be provided with one direct reading water level indicator (water gage glass), or two independent remote level indicators, that are maintained in simultaneous operation while the boiler is in service.       
        (3) In all installations where direct visual observations of the water gage glass(es) cannot be made, two remote level indicators shall be provided at operational level.       
        (4) The gage glass cock connections shall not be less than 1/2 inch nominal pipe size (15 mm).       
        (5) No outlet connections, except for feedwater regulators, drains, steam gages, or apparatus of such form as does not permit the escape of an appreciable amount of steam or water therefrom, shall be placed in the pipes connecting a water column or gage glass to a boiler.       
        (6) The water column shall be fitted with a drain cock or drain valve of at least 3/4 inch nominal pipe size (20 mm). The water column blowdown pipe shall not be less than 3/4 inch nominal pipe size (20 mm) and shall be piped to a safe point of discharge.       
        (7) Connections from the unfired steam boiler to remote level indicators shall be at least 3/4 inch nominal pipe size (20 mm), to and including the isolation valve, and at least 1/2 inch (13 mm) OD tubing from the isolation valve to the remote level indicator. These connections shall be completely independent of other connections for any function other than water level indication.       
      (f) Low-water cutoffs, alarms and feed regulating devices.      
        (1) The owner/operator is responsible for the design and installation of any low water protection devices as required to prevent damage to the unfired steam boiler. All installed low water cutoffs, alarms and feeding devices shall be designed for pressure and temperature equal to or greater than the MAWP of the unfired steam boiler.       
        (2) When a low-water cutoff, and/or alarm 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 cutoff and/or alarm device.       
        (3) Should an unfired steam boiler be installed in a system without a local and constant attendant, and it is not a fail-safe design, it shall be provided with a low-water cutoff as required for power boilers.       
      (g) Pressure gages.      
        (1) Each unfired steam boiler shall have a pressure gage that is readable. The dial of the pressure gage shall be graduated to approximately double the pressure at which the safety valve is set, but in no case, less than one and one-half times this pressure. The pressure gage shall be connected to the steam space, to the water column, or its steam connection. A valve or cock shall be placed in the gage connection adjacent to the gage. An additional valve or cock may be located near the boiler providing it is locked or sealed in the open position. No other shutoff valves shall be located between the gage and the boiler. The pipe connection shall be of ample size and arranged so that it may be cleared by blowing down. The gage or connection shall contain a siphon or equivalent device which will develop and maintain a water seal that will prevent steam from entering the gage tube.       
        (2) Each unfired steam boiler, must have a valved connection at least 1/4 inch nominal pipe size (8 mm), connected to the steam space for the exclusive purpose of attaching a test gage when the boiler is in service to test the accuracy of the pressure gage.       
      (h) Stop valves.      
        (1) Each steam outlet from an ASME Code, Section I unfired steam boiler, shall be fitted with a stop valve located as close as practicable to the boiler.       
        (2) When a stop valve is located such that it allows water to accumulate, ample drains shall be provided. The drain shall be piped to a safe location and shall not be discharged on the boiler or its setting.       
        (3) When boilers that are provided with manholes or other similar openings that permit access for human occupancy are connected to a common steam main, the owner or operator shall ensure that the boiler to which entry is being made is completely isolated from the steam main. This may be accomplished with the use of two stop valves with an ample drain between them, with a full isolation blind or removal of piping such that the boiler is no longer connected to the steam main.       
     Source Note:        The provisions of this §65.608 adopted to be effective June 15, 2015, 40 TexReg 3121; amended to be effective February 15, 2016, 41 TexReg 795; amended to be effective January 15, 2018, 43 TexReg 75; amended to be effective February 15, 2019, 44 TexReg 583