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 executive director, through the Board of Boiler Rules, to fix reasonable standards for the safe construction, installation, inspection and repair of boilers and pressure piping. This administrative regulation sets forth the specific requirements for power boilers which are within the scope of Section I of the ASME Boiler and Pressure Vessel Code. This amendment is necessary to comply with KRS Chapter 13A and to set forth additional specific requirements for new and existing power boilers which do not apply to other vessels.

 

      Section 1. New Installations. (1) Power boilers. All power boilers shall be constructed in accordance with applicable provisions of the ASME Boiler and Pressure Vessel Code incorporated in 815 KAR 15:025, Section 1(1), and Title 815 Chapter 15 of the Kentucky administrative regulations. Pressure piping beyond the first (or second) stop valve shall comply with the ASME Code for Pressure Piping adopted by reference in 815 KAR 15:025, Section 1(3).

      (2) Installation:

      (a) Vessels 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 such size, dimension and connected that it can be readily removed from its location for inspection.

      (b) Vessels having handholes, manholes, or cover plates to permit inspection of interior surfaces shall be so installed that these openings are readily accessible.

      (c) When cylindrical vessels are installed in a vertical position and subject to corrosion, the bottom head, if dished, should 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 inspector and shall not be obliterated by insulation or other covering not readily removable.

      (3) Pressure relieving devices (pressure vessels):

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

      (b) All pressure vessels other than unfired steam boilers shall be protected by a pressure relieving device that shall prevent the pressure within the vessel from rising more than five (5) percent above the maximum allowable working pressure (MAWP) when full open and discharging, except as in paragraphs (c) and (d) of this subsection. Unfired steam boilers shall have protective devices as required by this administrative regulation.

      (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) Where 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.

      (e) Pressure relieving devices shall be constructed, located, and installed so that they are readily accessible for inspection and repair and so that they 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, provided that the pilot is self-actuated and the main valve will open automatically at not over the set pressure and will discharge its full rated capacity if some essential part of the pilot should fail.

      (h) 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. 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 136 of ASME Pressure Vessel Code, Section VIII, Division 1.

 

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

      (2) Maximum allowable working pressure for nonstandard boilers.

      (a) The maximum allowable working pressure 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 subsection (h) of this section.

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

      1. TS = ultimate tensile strength of shell plates psi.

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

      3. E = efficiency of longitudinal joint.

      (c) For riveted construction, E may be determined under Paragraph PR-15 of ASME 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 Boiler and Pressure Vessel Code for Power Boilers.

      For seamless construction, E shall be considered 100 percent.

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

      FS = factor of safety permitted.

      (e) Tensile strength. When the tensile strength of steel or wrought iron shell plates is not known, it shall be taken at 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) Strength of rivets in shear. When computing 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.

      When 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. The following factors of safety shall be increased by the inspector if the condition and safety of the boiler demand it:

      1. The lowest factor of safety permissible on existing installations shall be four and five-tenths (4.5) 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 when the boiler is removed from its existing setting, it shall not be reinstalled for pressure in excess of fifteen (15) lbs. psig.

      2. Reinstalled or secondhand nonstandard boilers shall have a minimum factor of safety of six (6) when the longitudinal seams are of lap riveted construction and minimum factor of safety of five (5) when 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. Boilers having either longitudinal or circumferential seams of fusion welded construction shall have been constructed and stamped in accordance with the rules and regulations of the ASME 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 the ASME Code for Power Boilers and Pressure Vessels.

      (5) Cast iron headers and mud drums. The maximum allowable working pressure 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 for any cast iron boiler, except for hot water boilers, shall be fifteen (15) lbs. psig.

      (7) Safety valve requirements for power boilers:

      (a) The use of weight-level safety valves shall not be used and the valves shall be replaced by safety valves that conform to the requirements of the ASME Code for Power Boilers.

      (b) Safety valves 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 it has more than 500 square feet of water heating surface, it shall have two (2) or more safety valves.

      (d) Safety valves and safety relief valves shall be installed with their spindles vertical.

      (e) The method of computing the steam generating capacity of the boiler shall be as given in paragraph A-12 of the ASME Boiler and Pressure Vessel Code for Power Boilers. 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. Valves 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. 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. If an elbow is placed on a safety valve or discharge pipe, it shall be located close to the safety valve outlet. All safety valve discharges shall be located or piped to avoid endangering persons using walkways or platforms used to control the main valves of boilers or steam headers.

      (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.

      (g) For each boiler, one (1) or more safety valves on the boiler shall be set at or below the maximum allowable working pressure. If additional valves are used, the highest pressure setting shall not exceed the maximum allowable working pressure by more than three (3) percent. 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. 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. If the boiler is supplied with feed water directly from pressure mains without the use of feeding apparatus (not to include return taps), 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) following methods; and, if found to be insufficient, additional capacity shall be provided.

      1. By making the accumulation test, which consists of shutting off all other steam discharge outlets from the boiler and forcing the fires to the maximum. The safety valve capacity shall be sufficient to prevent a pressure in excess of six (6) percent above the maximum allowable working pressure. This method shall not be used on a boiler with a superheater or reheater.

      2. By measuring the maximum amount of fuel that can be burned and computing the corresponding evaporative capacity (steam generating capacity) upon the basis of the heating valve of this fuel. This computation may be made as outlined in the Appendix of the ASME Code for Power Boilers.

      3. By determining the maximum evaporative capacity by measuring the feed water.

      4. If either of the methods outlined above 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, as given in 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 may be based on the values given for hand-fired boiler above.

      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 allowed by paragraphs (b) through (f) of this subsection, boilers 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) All boilers shall have a feed supply which allows the boiler to be fed at any time while under pressure.

      (b) Boilers that are fired with solid fuel not in suspension and for boilers whose setting or heat source can continue to supply sufficient heat to cause damage to the boiler if the feed supply is interrupted, one (1) such means of feeding shall be steam operated.

      (c) Boilers fired by gas, liquid, or solid fuel in suspension, may be equipped with a single means of feeding water if furnished for the immediate shut off of the heat input if the water feed is interrupted. 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. 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) High temperature water boilers 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) The feed pipe to the boiler shall be provided with a check valve near the boiler and a valve or cock between the check valve and the boiler. If two (2) or more boilers are fed from a common source, there shall also be a globe or regulating valve on the branch to each boiler between the check valve and source of supply. If globe valves are used on feed piping, the inlet shall be under the disc of the valve. The valve shall be located as close to the boiler as is practicable.

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

      (9) Fusible plugs. Fire-actuated fusible plugs, if used, shall conform to the requirements of the ASME Boiler and Pressure Vessel Code for Power Boilers, Sections A-19, A-20 and A-21.

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

      (a) Outlet connections, except for damper regulator, feed water regulator, low-water fuel cutout, drains, steam gauges, 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. 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. The drain shall be piped to a safe location.

      (b) Each boiler shall have three (3) or more gauge cocks located within the range of the visible length of the water glass, except when 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 are sufficient for boilers not over thirty-six (36) inches in diameter in which the heating surface does not exceed 100 square feet.

      (c) Gauge cocks are not required for electric boilers operating at pressures not exceeding 400 psi. The gauge cock connections shall be not less than one-half (1/2) inch pipe size.

      (d) For all installations where the water gauge glass or glasses are more than thirty (30) feet from the boiler operating floor, it is recommended that water level indicating or recording gauges be installed at eye height from the operating floor.

      (11) Pressure gauges.

      (a) Each boiler shall have a pressure gauge connected to the steam space or to the water column or its steam connection. 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. 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 may be used near the boiler provided the valve is of the outside screw and yoke type and is locked or wired open. The line shall be ample size with provisions for free blowing.

      (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 when 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) If boilers provided with manholes are connected to a common main, the steam or high temperature water connection from each boiler shall be fitted with two (2) stop valves having an ample free blow drain between them. The discharge of this drain shall be visible to the operator while manipulating the valves and shall be piped clear of the boiler setting. 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 Section I of the ASME Boiler and Pressure Vessel Code.

      (13) Blow-off piping.

      (a) The construction of the setting around each blow-off pipe shall permit free expansion and contraction. Careful attention shall be given to the problem of sealing these setting openings without restricting the movement of the blow-off piping. All blow-off piping, when exposed to furnace heat, shall be protected by firebrick or other heat resisting material constructed to allow close inspection of the piping.

      (b) When the maximum allowable working pressure 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. The piping shall be of extra heavy wrought iron or steel and shall not be galvanized. All fittings between the boiler and blow-off valve shall be steel or extra heavy fittings of malleable iron. In case of renewal of blow-off pipe or fittings, they shall be installed in accordance with rules and administrative regulations for new installations.

      (14) Blowdown valves.

      (a) Ordinary type straight-run globe valves in which dams or pockets may exist for the collection of sediment shall not be used on these connections. Straightway Y-type globe valves or angle valves may be used in vertical pipes, or they may be used in horizontal runs of piping provided they are 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) The blow-off valve or valves and the pipe between them and the boiler shall be of the same size except where a larger pipe for the return of condensation is used as provided for by the ASME Boiler and Pressure Vessel Code for Power Boilers. On all boilers, except those used for high temperature water, traction or portable purposes, when 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 the ASME Boiler and Pressure Vessel Code for Power Boilers.

      (c) If a blow-off cock is used, the plug shall be held in place by a guard or gland. The plug shall be distinctly marked in line with the passage. 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) If a boiler has multiple blow-off pipes, a single master valve may be placed on the common blow-off pipe from the boiler, in which case 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. 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 Section I of the ASME Boiler and Pressure Vessel Code. 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 which 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 Paragraphs PG-58 and PG-59 of the ASME Boiler and Pressure Vessel Code, Section I.

      (d) The blowoff tank construction shall comply with ASME Pressure Vessel Code, Section VIII (Division I).

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

      (f) When a steam separator is used, it shall be designed to withstand at least twice the operating pressure of the separator and it 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) Piping connected to the outlet of a boiler, which comes with the ASME Boiler and Pressure Vessel Code requirements, shall be attached as follows:

      1. Screwing into a tapped opening with a screwed fitting or a valve at the other end.

      2. Screwing each end into tapered flanges, fittings, or valves with or without rolling or peening.

      3. Bolted joints, including those of the Van Stone type.

      4. Expanding into grooved holes, seal welding, if desired. Pipe which is expanded, rolled, or peened shall be made from open-hearth or electric-furnace steel.

      (b) If exposed to products of combustion, blow-off piping of fire-tube boilers shall be attached as outlined in paragraph 1 of subsection (a) of this section. If not so exposed to products of combustion, the piping shall be attached as outlined in paragraph (a)1, 2 or 3 of this subsection. Fusion welding for sealing purposes at the junction of bolted joints may be used.

      (c) Welding may be used to attach piping to nozzles or fittings if the rules for fusion welding or forge welding are followed. 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 American Society of Mechanical Engineers Code symbol stamps for pressure piping, power boilers or assembly stamps. 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 American Society of Mechanical Engineers when approved by the inspector. (Recodified from 806 KAR 50:165, 7-5-78; Am. 16 Ky.R. 67; eff. 8-22-89; 20 Ky.R. 2731; 2981; eff. 5-18-94; TAm eff. 8-9-2007.)