1. (a)

   1. (1) No person shall in any manner load the safety valve or relief valve to a greater pressure than that allowed in the certificate of inspection.
   2. (2) Dead weight or weighted-lever safety valves shall not be used.
   3. (3) Each boiler, if it is subject to the provisions of Section 1 of the ASME code, shall have at least one (1) safety valve and if it has more than five hundred square feet (500 ft²) of water heating surface, it shall have two (2) or more safety valves.
   4. (4) The method of computing the steam-generating capacity of the boiler shall be in compliance with the ASME code, as adopted.

2. (b)

   1. (1) The safety-valve capacity for each boiler shall be such that the safety valve or valves will discharge all the steam that can be generated by the boiler without allowing the pressure to rise more than six percent (6%) above the highest pressure at which any valve is set and in no case to more than six percent (6%) above the maximum allowable working pressure.
   2. (2) The maximum steaming capacity of a boiler shall be determined by the manufacturer and shall be based on the capacity of the fuel-burning equipment, on the air supply, draft, etc.

3. (c)

   1. (1) One (1) or more safety valves on the boiler proper shall be set at or below the maximum allowable working pressure.
   2. (2) If additional valves are used, the highest pressure setting shall not exceed the maximum allowable working pressure by more than three percent (3%).
   3. (3) The complete range of pressure settings of all the saturated steam safety valves on a boiler shall not exceed ten percent (10%) of the highest pressure to which any valve is set.

4. (d)

   1. (1)

      1. (A) All safety valves shall be so constructed that the failure of any part cannot obstruct the free and full discharge of steam from the valve.
      2. (B) Safety valves shall be of the direct spring-loaded pop type, with seat inclined at any angle between forty-five degrees and ninety degrees (45° and 90°), inclusive, to the center line of the spindle.
      3. (C) The maximum rated capacity of a safety valve shall be determined by actual steam flow at a pressure of three percent (3%) in excess of that at which the valve is set to blow, and shall operate without chattering and shall be set and adjusted as follows, to close after blowing down not more than four percent (4%) of the set pressure but not less than two pounds (2 lbs.) in any case.

   2. (2)

      1. (A) For spring-loaded pop safety valves for pressures between one hundred pounds per square inch (100 psi) and three hundred pounds per square inch (300 psi), both inclusive, the blowdown shall be not less than two percent (2%) of the set pressure.
      2. (B) To ensure the guaranteed capacity of satisfactory operation, the blowdown as marked upon the valve shall not be reduced.

5. (e)

   1. (1) Safety valves used on forced-circulation boilers of the once through type may be set and adjusted to close after blowing down not more than ten percent (10%) of the set pressure.
   2. (2) The valve for this special use must be so adjusted and marked by the manufacturer.
6. (f) The blowdown adjustment shall be made and sealed by the manufacturer.

7. (g) The popping point tolerance plus or minus shall not exceed the following:

   1. (1) Two pounds (2 lbs.) for pressures up to and including seventy pounds (70 lbs.);
   2. (2) Three percent (3%) for pressures from seventy-one pounds (71 lbs.) to three hundred pounds (300 lbs.); and
   3. (3) Ten pounds (10 lbs.) for pressures over three hundred pounds (300 lbs.).

8. (h)

   1. (1) Each safety valve shall be plainly marked by the manufacturer in such a way that the markings will not be obliterated in service.

   2. (2) The markings may be stamped on the casing or stamped or cast on a plate or plates securely fastened to the casing, and shall contain the following markings:

      1. (A) The name or identifying trademark of the manufacturer;
      2. (B) Manufacturer’s design or type number;
      3. (C)

9. (i) Size _____in. seat diameter _____in.

   1. (ii) The pipe size of the valve inlet;

      1. (D)

         1. (i) SET-pressure _____lb.
         2. (ii) The steam pressure at which it is to blow;

      2. (E)

         1. (i) Capacity _____lb. per hr.
         2. (ii) As stated above and with the valve adjusted to the blowdown given in the preceding item;

      3. (F)

         1. (i) Capacity lift _____in.
         2. (ii) “Capacity lift” means the distance the valve disc rises under the action of the steam when the valve is blowing under a pressure of three percent (3%) above set pressure;
      4. (G) Year built __________; and

      5. (H) ASME symbol as shown in the ASME code.

         1. (i) If the safety-valve capacity cannot be computed or if it is desirable to prove the computations, it may be checked in any one (1) of the three (3) following ways, and if found insufficient, additional capacity shall be provided:

   2. (1)

      1. (A) By making an accumulation test, that is, by shutting off all other steam-discharge outlets from the boiler and forcing the fires to the maximum.
      2. (B) The safety valve equipment shall be sufficient to prevent an excess pressure beyond that specified previously;
   3. (2) By measuring the maximum amount of fuel that can be burned and computing the corresponding evaporative capacity upon the basis of the heating value of the fuel as outlined in the ASME Code for Power Boilers, as adopted; or

   4. (3)

      1. (A) By determining the maximum evaporative capacity by measuring the feedwater.
      2. (B) The sum of the safety valve capacities marked on the valves shall be equal to or greater than the maximum evaporative capacity of the boiler.
10. (j) All firms that are in the business of repairing safety or temp/relief valves shall be qualified and hold a VR certificate of authorization from the National Board of Boiler and Pressure Vessel Inspectors.

11. (k)

    1. (1) Any firm or corporation operating within the state that has their own qualified personnel and quality control program may repair and reset their own valves.

    2. (2) Each firm or corporation shall submit a copy of their Q.C. program to the Boiler Inspection Division.

       1. (l)
    3. (1) When two (2) or more safety valves are used on a boiler, they may be mounted either separately or as twin valves made by placing individual valves on Y bases, or duplex valves having two (2) valves in the same body casing.

    4. (2) Twin valves made by placing individual valves on Y bases, or duplex valves having two (2) valves in the same body, shall be of equal size.

       1. (m) When not more than two (2) valves of different sizes are mounted singly, the relieving capacity of the smaller valve shall be not less than fifty percent (50%) of that of the larger one.

12. (n)

    1. (1) The safety valve or valves shall be connected to the boiler independent of any other steam connection and attached as close as possible to the boiler, without any unnecessary intervening pipe or fitting.
    2. (2) Every safety valve or valves shall be connected so as to stand in an upright position, with spindle vertical.

13. (o)

    1. (1) The opening or connection between the boiler and the safety valve shall have at least the area of the valve inlet.

    2. (2)

       1. (A) In the case of fire-tube boilers, the openings in the boilers for safety valves shall not be less than in the ASME code, as adopted, except fire-tube boilers used for waste heat purposes only, and which are not equipped for direct firing.
       2. (B) This type boiler need not meet the requirements of the code provided the rated steam capacity is stamped on the boiler and safety valves of the required relieving capacity are supplied so that the provisions of subsection (b) of this section are satisfied.
    3. (4) No valve of any description shall be placed between the required safety valve or valves and the boiler, or on the discharge pipe between the safety valve and the atmosphere.

    4. (5) When a discharge pipe is used, the cross-sectional area shall be:

       1. (A) Not less than the full area of the valve outlet or of the total of the areas of the valve outlets discharging therein; and
       2. (B) As short and straight as possible and so arranged as to avoid undue stresses on the valve or valves.

14. (p)

    1. (1) All safety-valve discharges shall be so located or piped as to be carried clear from the running boards or platforms.

    2. (2) Ample provisions for gravity drain shall be made:

       1. (A) In the discharge pipe at or near each safety valve; and
       2. (B) Where water or condensation may collect.
    3. (3) Each valve shall have an open gravity drain through the casing below the level of the valve seat.
    4. (4) For iron and steel-bodied valves exceeding two-inch size, the drain hole shall be tapped not less than three-eighths-inch pipe size.

15. (q)

    1. (1) If a muffler is used on a safety valve, it shall have sufficient outlet area to prevent back pressure from interfering with the proper operation and discharge capacity of the valve.
    2. (2) The muffler plates or other devices shall be so constructed as to avoid any possibility of restriction of the steam passages due to deposit.
16. (r) When a boiler is fitted with two (2) or more safety valves on one (1) connection, this connection to the boiler shall have a cross-sectional area not less than the combined areas of inlet connections of all the safety valves with which it connects.

Codification Notes: “Q.C.” means quality control.