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

Link to law: http://www.lrc.ky.gov/kar/815/015/040.htm
Published: 2015

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      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.)