815 KAR 15:040. Power boiler and pressure vessel supplemental requirements.

 

      RELATES TO: KRS 236.030

      STATUTORY AUTHORITY: KRS 236.030

      NECESSITY, FUNCTION, AND CONFORMITY: KRS 236.030 authorizes the commissioner, through the Board of Boiler and Pressure Vessel Rules, to fix reasonable standards for the safe construction, installation, inspection, and repair of boilers and pressure piping. This administrative regulation establishes the specific requirements for power boilers that are within the scope of Section I of the ASME Boiler and Pressure Vessel Code.

 

      Section 1. New Installations. (1) Power boilers.

      (a) A power boiler shall be constructed in accordance with applicable provisions of the ASME Boiler and Pressure Vessel Code incorporated in 815 KAR 15:025 and 815 KAR Chapter 15.

      (b) Pressure piping beyond the first (or second) stop valve shall comply with the codes and standards applicable to pressure piping as established by 815 KAR 15:025, Section 1(4).

      (2) Installation.

      (a) A vessel subject to external corrosion shall be so installed that there is sufficient access to all parts of the exterior to permit proper inspection of the exterior surfaces, otherwise sufficient protection against corrosion shall be provided, or the vessel shall be of a size, dimension, and connection that the vessel can be readily removed from its location for inspection.

      (b) A vessel having a handhole, manhole, or cover plate to permit inspection of interior surfaces shall be so installed that each opening is readily accessible.

      (c) If a cylindrical vessel is installed in a vertical position and subject to corrosion, the bottom head, if dished, shall be concave to pressure to facilitate proper drainage.

      (d) The installed vessel shall be so located that the stamping or marking shall be accessible to the boiler inspector, special inspector, or owner-user inspector and shall not be obstructed by insulation or other covering not readily removable.

      (3) Pressure relieving devices (pressure vessels).

      (a) A single pressure relieving device shall be set to operate at a pressure not exceeding the maximum allowable working pressure (MAWP) of the vessel.

      (b)1. A pressure vessel other than an unfired steam boiler shall be protected by a pressure relieving device that shall prevent the pressure within the vessel from rising more than ten (10) percent above the maximum allowable working pressure (MAWP) when full open and discharging, except as established in paragraphs (c), (d), and (j) of this subsection.

      2. An unfired steam boiler shall have protective devices as required by this administrative regulation.

      3. An unfired steam boiler shall be equipped with pressure relieving devices required by ASME Section I.

      (c) The aggregate capacity of the pressure relieving devices connected to any vessel or system of vessels for the release of a liquid, air, steam, or other vapor shall be sufficient to discharge the maximum quantity that can be generated or supplied to the attached equipment without permitting a rise in pressure within the vessel or more than sixteen (16) percent above the maximum allowable working pressure (MAWP) of the vessel when all pressure relieving devices are full open and discharging.

      (d) If an additional hazard can be created by exposure of a pressure vessel to fire or other unexpected sources of external heat, supplemental pressure relieving devices shall be installed capable of protecting against excessive pressure. These supplemental pressure relieving devices shall be capable of preventing the pressure from rising more than twenty-one (21) percent above the maximum allowable working pressure (MAWP).

      (e) A pressure relieving device shall be constructed, located, and installed so that the device is readily accessible for inspection and repair and cannot be readily rendered inoperative and shall be selected on the basis of their intended service.

      (f) Safety, safety relief, and relief valves shall be of the direct spring loaded type.

      (g) Pilot operated pressure relief valves may be used. The pilot shall be self-actuated and the main valve shall open automatically at not over the set pressure and shall discharge the valve’s full rated capacity if some essential part of the pilot should fail.

      (h)1. The spring in a pressure relief valve in service for pressures up to and including 250 psi shall not be reset for any pressure more than ten (10) percent above or below that for which the valve is marked.

      2. For higher pressures, the spring shall not be reset for any pressure more than five (5) percent above or five (5) percent below that for which the safety or relief valve is marked.

      (i) The set pressure tolerances, plus or minus, of pressure relief valves shall not exceed two (2) psi for pressures up to and including seventy (70) psi and three (3) percent for pressures above seventy (70) psi. All other requirements regarding over pressure protection devices shall be in accordance with UG-125 through UG-140 of ASME Pressure Vessel Code, Section VIII, Division 1.

      (j)1. If a pressure relieving device is omitted or removed, the device shall be omitted or removed in accordance with ASME Section VIII, Division 1, UG-140, Appendix M and ASME Section VIII, Division 2, Part 9, or Division 3, Part KR.

      2. If a pressure relieving device is omitted or removed pursuant to the standards established in subparagraph 1. of this paragraph, except ASME Section VIII, Division 1, Appendix M., the Boiler Section shall be notified prior to the omission or removal, and prior to the pressure vessel being placed in service.

      3. The required documentation shall be submitted to the Boiler Section for review and acceptance or rejection of the proposed omission or removal.

 

      Section 2. Maximum Allowable Working Pressure for Existing Installations. (1) Maximum allowable working pressure (MAWP) for standard boilers and pressure vessels. The maximum allowable working pressure (MAWP) for a standard boiler or pressure vessel shall be determined in accordance with the applicable provision of the edition of ASME Boiler and Pressure Vessel Code under which the boiler or pressure vessel was constructed and stamped.

      (2) Maximum allowable working pressure (MAWP) for nonstandard boilers.

      (a) The maximum allowable working pressure (MAWP) on the shell of a nonstandard boiler, pressure vessel, or drum shall be determined by the strength of the weakest section of the structure, computed from the thickness of the plate, the tensile strength of the plate, the efficiency of the longitudinal joint or tube ligaments, the inside diameter of the weakest course, and the factor of safety allowed by paragraph (h) of this subsection.

      (b) Formulas. (TS times t times E) divided by (R times FS) equals maximum allowable working pressure in psig; where:

      TS = ultimate tensile strength of shell plates psi.

      t = minimum thickness of shell plate, of weakest course, in inches.

      E = efficiency of longitudinal joint.

      R = inside radius of the weakest course of the shell or drum in inches.

      FS = factor of safety permitted.

      (c) For riveted construction, E shall be determined under Paragraph A-30 of ASME Section I, Boiler and Pressure Vessel Code for Power Boilers.

      (d) For tube ligaments, E shall be determined by rules given in Paragraphs PG-52 and 53 of ASME Section I, Boiler and Pressure Vessel Code for Power Boilers. For seamless construction, E shall be considered 100 percent.

      (e) Tensile strength. If the tensile strength of steel or wrought iron shell plates is not known, the tensile strength shall be assumed to be 55,000 psi for steel and 45,000 psi for wrought iron.

      (f) Crushing strength of mild steel. The resistance to crushing of mild steel shall be taken at 95,000 psi of cross section area.

      (g)1. Strength of rivets in shear. In order to compute the ultimate strength of rivets in shear, the following values in pounds psi of the cross sectional area of the rivet shank shall be used:

Iron rivets in single shear

38,000 lbs.

Iron rivets in double shear

76,000 lbs.

Steel rivets in single shear

44,000 lbs.

Steel rivets in double shear

88,000 lbs.

      2. If the diameter of the rivet holes in the longitudinal joints of a boiler is not known, the diameter and cross sectional area of rivets, after driving, may be selected from the following table or as ascertained by cutting out one (1) rivet in the body of the joint:

SIZES OF RIVETS BASED ON PLATE THICKNESS

(In Inches)

Thickness of plate

1/4

9/32

5/16

11/32

3/8

13/32

Diameter of rivet after driving

11/16

11/16

3/4

3/4

13/16

13/16

Thickness of plate

7/16

15/32

1/2

9/16

5/8

-----

Diameter of rivet after driving

15/16

15/16

15/16

1 1/16

1 1/16

-----

      (h) Factors of safety. Factors of safety shall be increased by the boiler inspector or special inspector if required by the condition and safety of the boiler.

      1. The lowest factor of safety permissible on existing installations shall be four and one-half (4 1/2) except for horizontal return tubular boilers having continuous longitudinal lap seams more than twelve (12) feet in length where the factor of safety shall be eight (8), but if the boiler is removed from its existing setting, the boiler shall not be reinstalled for pressure in excess of fifteen (15) lbs. psig.

      2. A reinstalled or secondhand nonstandard boiler shall have a minimum factor of safety of six (6) if the longitudinal seams are of lap riveted construction and minimum factor of safety of five (5) if the longitudinal seams are of butt and double strap construction.

      (3) Age limit of fire tube boilers. The age limit of a horizontal return tubular, flue, or cylinder boiler having a longitudinal lap joint and operating at a pressure in excess of fifty (50) lbs. psig shall be twenty (20) years.

      (4) Welded boilers. A boiler having either longitudinal or circumferential seams of fusion welded construction shall have been constructed and stamped in accordance with ASME Section I, Boiler and Pressure Vessel Code for Power Boilers or shall have the standard stamping of a state that has adopted a standard of construction equivalent to the standards of ASME Section I.

      (5) Cast iron headers and mud drums. The MAWP on a water tube boiler, the tubes of which are secured to cast iron or malleable iron headers, or which have cast iron mud drums, shall not exceed 160 lbs. psig.

      (6) Pressure on cast iron boilers. The maximum allowable working pressure (MAWP) for any cast iron boiler, except for hot water boilers, shall be fifteen (15) lbs. psig.

      (7) Safety valve requirements for power boilers.

      (a) A weighted lever safety valve shall not be used and the valve shall be replaced by a safety valve that conforms to the requirements of ASME Section I.

      (b) A safety valve having either the seat or disc of cast iron shall not be used.

      (c) Each boiler shall have at least one (1) safety valve, and, if the boiler has more than 500 square feet of water heating surface, the boiler shall have two (2) or more safety valves.

      (d) A safety valve and a safety relief valve shall be installed with the valve’s spindles vertical.

      (e)1. The method of computing the steam generating capacity of the boiler shall be as established in paragraph A-12 of ASME Section I.

      2. The safety valve or valves shall be connected to the boiler, independent of any other steam connection, and attached to the boiler, without intervening pipe or fittings. If alteration is required to conform to this requirement, owners and users shall be allowed one (1) year in which to complete the work.

      3. A stop valve shall not be placed between the safety valve and the boiler or on the discharge pipe (if used) between the safety valve and the atmosphere.

      4. If a discharge pipe is used, it shall be full sized and fitted with an open drain to prevent water lodging in the upper part of the safety valve or discharge pipe and supported independently of the safety valve.

      5. If an elbow is placed on a safety valve or discharge pipe, it shall be located close to the safety valve outlet.

      6. A safety valve discharge shall be located or piped to avoid endangering persons using a walkway or platform used to control the main valves of a boiler or steam header.

      (f) The safety valve capacity of each boiler shall be sufficient to allow the safety valve or valves to discharge all the steam generated by the boiler without allowing the pressure to rise more than six (6) percent above the maximum allowable working pressure (MAWP).

      (g)1. For each boiler, one (1) or more safety valves on the boiler shall be set at or below the maximum allowable working pressure (MAWP). If an additional valve is used, the highest pressure setting shall not exceed the maximum allowable working pressure (MAWP) by more than three (3) percent.

      2. The complete range of pressure settings of all of the saturated steam safety valves on a boiler shall not exceed ten (10) percent of the highest pressure to which any valve is set.

      3. If two (2) or more 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 generating capacity of all boilers.

      4. If the boiler is supplied with feed water directly from a pressure main without the use of feeding apparatus (not to include return taps), the safety valve shall not be set at a pressure greater than ninety-four (94) percent of the lowest pressure obtained in the supply main feeding the boiler.

      (h) The relieving capacity of the safety valves on any boiler may be checked by one (1) of the three (3) methods established in subparagraphs 1. through 3. of this paragraph; and, if found to be insufficient, additional capacity shall be provided.

      1.a. The accumulation test shall consist of shutting off all other steam discharge outlets from the boiler and forcing the fires to the maximum.

      b. The safety valve capacity shall be sufficient to prevent a pressure in excess of six (6) percent above the maximum allowable working pressure (MAWP).

      c. This method shall not be used on a boiler with a superheater or reheater.

      2.a. The maximum amount of fuel that can be burned shall be measured and the corresponding evaporative capacity (steam generating capacity) shall be computed upon the basis of the heating valve of this fuel.

      b. This computation may be made as outlined in the Appendix of the ASME Code for Power Boilers.

      3. The maximum evaporative capacity shall be determined by measuring the feed water.

      4. If either of the methods established in subparagraphs 1. through 3. of this paragraph is employed, the sum of the safety valve capacity shall be equal to or greater than the maximum evaporative capacity (maximum steam generating capacity) of the boiler. The minimum safety valve or safety relief valve relieving capacity for other than electric boilers shall be determined on the basis of the pounds of steam generated per hour per square foot of boiler heating surface and water wall heating surface, in accordance with the following table:

MINIMUM POUNDS OF STEAM PER HOUR

PER SQUARE FOOT OF SURFACE

 

Fire Tube Boilers

Water Tube Boilers

Boiler heating surface

 

Hand-fired

5

6

Stoker-fired

7

8

Oil-, gas-, or pulverized-fuel-fired

8

10

Waterwall heating surface

 

Hand-fired

8

8

Stoker-fired

10

12

Oil-, gas-, or pulverized-fuel-fired

14

16

      a. If a boiler is fired only by a gas having a heat value in excess of 200 BTU per cubic foot, the minimum safety valve or safety relief valve relieving capacity shall be based on the values given for a hand-fired boiler in the table established in this subparagraph.

      b. The minimum safety valve or safety relief valve relieving capacity for electric boilers shall be three and one-half (3 1/2) pounds per hour per kilowatt input.

      (8) Boiler feeding and feed piping. Except as established in paragraphs (b) through (f) of this subsection, a boiler having more than 500 square feet of water-heating surface shall have at least two (2) means of feeding water. Each source of feeding shall be capable of supplying water to the boiler at a pressure of three (3) percent higher than the highest setting of any safety valve on the boiler.

      (a) Each boiler shall have a feed supply that allows the boiler to be fed at any time while under pressure.

      (b) A boiler that is fired with solid fuel not in suspension or a boiler that the setting or heat source can continue to supply sufficient heat to cause damage to the boiler if the feed supply is interrupted, one (1) of the means of feeding water required by this subsection shall be steam operated.

      (c) 1. A boiler that is fired by gas, liquid, or solid fuel in suspension may be equipped with a single means of feeding water if the boiler’s heat input is immediately shut off by any interruption in the water feed.

      2. If the boiler has a water-heating surface of not more than 100 square feet, the feed piping and connection to the boiler shall not be smaller than one-half (1/2) inch pipe size.

      3. If the boiler has a water-heating surface more than 100 square feet, the feed piping and connection to the boiler shall not be less than three-fourths (3/4) inch pipe size.

      (d) A high temperature water boiler shall be provided with means of adding water to the boiler or system while under pressure. The feed water shall be introduced into the boiler to prevent its discharge close to riveted joints of the shell, furnace sheets, directly against surfaces exposed to gases at high temperature or direct radiation from the fire.

      (e)1. The feed pipe to the boiler shall be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler.

      2. If two (2) or more boilers are fed from a common source, there shall also be a stop valve or regulating valve on the branch to each boiler between the check valve and source of supply. The stop valve or regulating valve shall be located as close to the boiler as is practicable.

      3. If a globe valve is used on feed piping, the inlet shall be under the disc of the valve.

      (f) If a de-aerating heater is not employed, the temperature of the feed water shall be no less than 120 degrees Fahrenheit to avoid the possibility of setting up localized stress. If a de-aerating heater is employed, the minimum feed water temperature shall be no less than 215 degrees Fahrenheit so that dissolved gases will be thoroughly released.

      (9) Fusible plugs. A fire-actuated fusible plug, if used, shall conform to the requirements of ASME Section I, Paragraphs A-19, A-20 and A-21.

      (10) Water columns, gauge glasses, and gauge cocks.

      (a) 1. An outlet connection, except for a damper regulator, feed water regulator, low-water fuel cutout, drain, steam gauge, or apparatus that does not permit the escape of an appreciable amount of steam or water, shall not be placed on the piping that connects the water column to the boiler.

      2. The minimum size of the steam and water connection to the water column shall be one (1) inch pipe size, and each water column shall be provided with a valved drain of at least three-fourths (3/4) inch pipe size.

      3. The drain shall be piped to a safe location.

      (b) Each manually fired boiler shall comply with ASME Section I, except a manually fired boiler built before the publication of the 1991 Addenda to ASME Section I (1989 Edition), which shall have three (3) or more gauge cocks located within the range of the visible length of the water glass, except if the boiler has two (2) water glasses with independent connections to the boiler located on the same horizontal lines and not less than two (2) feet apart. Two (2) gauge cocks shall be sufficient for boilers not over thirty-six (36) inches in diameter in which the heating surface does not exceed 100 square feet.

      (c) Each automatically fired boiler shall comply with ASME Section I.

      (d) For an installation in which the water gauge glass or glasses are more than thirty (30) feet from the boiler operating floor, water level indicating or recording gauges shall be installed at eye height from the operating floor.

      (11) Pressure gauges.

      (a)1. Each boiler shall have a pressure gauge connected to the steam space or to the water column or its steam connection.

      2. The pressure gauge shall be connected to a siphon or equivalent device of sufficient capacity to keep the gauge tube filled with water and so arranged that the gauge cannot be shut off from the boiler except by a cock placed near the gauge and provided with a tee or lever handle arranged to be parallel to the pipe in which it is located when the cock is open.

      3. The dial of the pressure gauge shall be graduated to approximately double the pressure at which the safety valve is set, but, in no case to less than one and one-half (1 1/2) times the pressure.

      (b) If a pressure gauge connection longer than eight (8) feet becomes necessary, a shutoff valve shall be used near the boiler provided the valve is of the outside screw and yoke type and is locked or wired open.

      (c) Each boiler shall be provided with a one-fourth (1/4) inch nipple and globe valve connected to the steam space for the exclusive purpose of attaching a test gauge if the boiler is in service so that the accuracy of the boiler pressure gauge may be ascertained.

      (12) Stop valves.

      (a) Each outlet from a boiler (except safety valve connections) shall be fitted with a stop valve located as close as practicable to the boiler.

      (b)1. If a boiler provided with a manhole is connected to a common main, the steam or high temperature water connection from the boiler shall be fitted with two (2) stop valves having an ample free blow drain between them.

      2. The discharge of this drain shall be visible to the operator while manipulating the valves and shall be piped clear of the boiler setting.

      3. The stop valves shall consist of one (1) automatic nonreturn valve (set next to the boiler) and a second valve of the outside screw and yoke type shall be installed in accordance with ASME Section I.

      (13) Blow-off piping.

      (a)1. The construction of the setting around each blow-off pipe shall permit free expansion and contraction.

      2. Attention shall be given to the problem of sealing the setting openings without restricting the movement of the blow-off piping.

      3. All blow-off piping, if exposed to furnace heat, shall be protected by firebrick or other heat resisting material constructed to allow close inspection of the piping.

      (b)1. If the maximum allowable working pressure (MAWP) exceeds 100 psig, blow-off piping shall be extra heavy from the boiler to the valve or valves, and shall be run full size without use of reducers or bushings.

      2. The piping shall be of extra heavy wrought iron or steel and shall not be galvanized.

      3. All fittings between the boiler and blow-off valve shall be steel or extra heavy fittings of malleable iron.

      4. In case of renewal of blow-off pipe or fittings, installation shall be in accordance with 815 KAR 15:025.

      (14) Blowdown valves.

      (a)1. Ordinary type straight-run globe valves in which dams or pockets may exist for the collection of sediment shall not be used.

      2. Straightway Y-type globe valves or angle valves may be used in vertical pipes or in horizontal runs of piping if the pipe is so constructed or installed allowing the lowest edge of the opening through the seat to be at least twenty-five (25) percent of the inside diameter below the center line of the valve.

      (b)1. The blow-off valve or valves and the pipe between them and the boiler shall be of the same size except if a larger pipe for the return of condensation is used as provided for by ASME Section I.

      2. On all boilers, except those used for high temperature water, traction or portable purposes, if the allowable working pressure exceeds 100 psi, each bottom blow-off pipe shall have two (2) slow-opening valves, or one (1) slow-opening valve and a quick-opening valve, or a cock complying with the requirements of ASME Section I.

      (c)1. If a blow-off cock is used, the plug shall be held in place by a guard or gland and the plug shall be distinctly marked in line with the passage.

      2. A slow-opening valve requires at least five (5) 360-degree turns of the operating mechanism to change from full-closed to full-opening, or vice versa.

      (d)1. If a boiler has multiple blow-off pipes, and has a single master valve placed on the common blow-off pipe from the boiler, only one (1) valve on each individual blow-off shall be required. In this case, either the master valve or the individual valves or cocks shall be of the slow-opening type, or a slow-opening valve and a quick-opening valve or cock may be combined in one (1) body and may be used if the combined fitting is the equivalent of two (2) independent slow-opening valves or a slow-opening valve and a quick-opening valve or cock and if the failure of one (1) to operate cannot affect the operation of the other.

      2. The bottom blow-off pipes of every traction engine or portable boiler shall have at least one (1) slow-opening or quick-opening blow-off valve or cock conforming to the requirements of ASME Section I.

      3. Only one (1) blow-off valve, which shall be of a slow-opening type, shall be required on forced circulation and electric boilers having a normal water content not exceeding 100 gallons.

      (15) Boiler blowoff equipment. The blowdown from a boiler or boilers that enters a sanitary sewer system or blowdown that is considered a hazard to life or property shall pass through some form of blowoff equipment that will reduce pressure and temperature as required hereinafter.

      (a) The temperature of the water leaving the blowoff equipment shall not exceed 150 degrees Fahrenheit.

      (b) The pressure of the blowdown leaving any type of blowoff equipment shall not exceed five (5) psig.

      (c) The blowoff piping and fittings between the boiler or boilers and the blowoff tank(s) shall comply with ASME Section I, Paragraphs PG-58 and PG-59.

      (d) The blowoff tank construction shall comply with ASME Section VIII.

      (e) All materials used in the fabrication of boiler blowoff equipment shall comply with Material of ASME Section II.

      (f) If a steam separator is used, the separator shall be designed to withstand at least twice the operating pressure of the separator and shall be equipped with a vent, inlet, outlet, and a pressure gauge.

      (g) All blowoff equipment shall be fitted with openings to facilitate cleaning and inspection.

      (h) A copy of a booklet for the design, construction and arrangement of boiler blowoff equipment may be obtained from the National Board of Boiler and Pressure Vessel Inspectors, whose address is 1055 Crupper Avenue, Columbus, Ohio 43229.

      (16) Piping.

      (a) Boiler external piping shall be attached in accordance with ASME Section I and B31.1.

      (b)1. If two (2) or more boilers with manholes are connected to a common steam or high temperature water main or header, all welded external piping from the boiler out to the second stop valve shall be installed by a manufacturer or contractor authorized to use any one (1) of the ASME Code symbol stamps for pressure piping, power boilers, or assembly stamps.

      2. The piping or fittings, adjacent to the welded joint farthest from the boiler, shall be stamped with the pressure piping, power boiler, or assembly code symbol stamp of the ASME when approved by the boiler inspector, special inspector, or owner-user inspector. (Recodified from 806 KAR 50:165, 7-5-1978; Am. 16 Ky.R. 67; eff. 8-22-1989; 20 Ky.R. 2731; 2981; eff. 5-18-1994; TAm eff. 8-9-2007; 42 Ky.R. 1631; 2116; eff. 2-5-2016.)