296-307-410 Storage and handling of liquefied
petroleum gases.
296-307-41001 What does this part cover?
296-307-41003 Which LP-gas installations are not covered by this part?
296-307-41005 What definitions apply to this part?
296-307-41007 When must LP-gas be odorized?
296-307-41009 Must LP-gas containers and equipment be approved?
296-307-41011 What construction and test requirements must containers
meet?
296-307-41013 How must containers be welded?
296-307-41015 How must containers be marked?
296-307-41017 Where must containers be located?
296-307-41019 What requirements apply to valves and accessories?
296-307-41021 What requirements apply to piping, tubing, and fittings?
296-307-41023 What specifications must hoses meet?
296-307-41025 What requirements apply to safety devices?
296-307-41027 How must indirect fired vaporizers be constructed and
installed?
296-307-41029 How must atmospheric vaporizers be constructed and installed?
296-307-41031 How must direct gas-fired vaporizers be constructed
and installed?
296-307-41033 How must direct gas-fired tank heaters be constructed
and installed? 296-307-41035 How must dehydrators be constructed and installed?
296-307-41037 What are the maximum filling densities?
296-307-41039 What requirements apply to LP-gas in buildings?
296-307-41041 What requirements apply to transfer of liquids?
296-307-41043 Must workers be trained?
296-307-41045 What fire protection must be provided for LP-gas installations?
296-307-41047 What electrical requirements apply to LP-gas installations?
296-307-41049 What requirements apply to liquid-level gauging devices?
296-307-41051 What requirements apply to appliances?
296-307-415 Cylinder systems.
296-307-41501 What does this section cover?
296-307-41503 What is a “cylinder system?”
296-307-41505 How must containers be marked for cylinder systems?
296-307-41507 What additional requirements apply to cylinder systems
installed outdoors?
296-307-41509 What additional requirements apply to cylinder systems
installed indoors?
296-307-41511 What requirements apply to valves and accessories?
296-307-41513 What requirements apply to safety devices for cylinder
systems?
296-307-41515 What other requirements apply to cylinder systems?
296-307-420 Systems using non-DOT containers.
296-307-42001 What does this section cover?
296-307-42003 How must non-DOT containers be designed and classified?
296-307-42005 What requirements apply to valves and accessories, filler
pipes, and discharge pipes for non-DOT containers.
296-307-42007 What additional requirements apply to safety devices
for non-DOT containers?
296-307-42009 When may non-DOT containers be reinstalled?
296-307-42011 What is the maximum capacity allowed for non-DOT containers?
296-307-42013 How must non-DOT containers be installed?
296-307-42015 How must non-DOT containers be protected?
296-307-42017 What requirements apply to non-DOT containers in industrial
plants?
296-307-42019 What requirements apply to container-charging plants?
296-307-42021 What fire protection must be provided for non-DOT containers?
296-307-42023 What other requirements apply to non-DOT containers?
296-307-425 LP-gas as a motor fuel.
296-307-42501 What does this section cover?
296-307-42503 What general requirements apply to LP-gas used as a
motor fuel?
296-307-42505 How must fuel containers be designed and classified?
296-307-42507 How must fuel containers be installed?
296-307-42509 What requirements apply to valves and accessories?
296-307-42511 What requirements apply to piping, tubing, and fittings?
296-307-42513 What requirements apply to safety devices?
296-307-42515 What requirements apply to vaporizers?
296-307-42517 What requirements apply to gas regulating and mixing
equipment?
296-307-42519 What is the maximum container capacity allowed?
296-307-42521 What requirements apply to stationary engines used indoors?
296-307-42523 What requirements apply to portable engines used indoors?
296-307-42525 What requirements apply to industrial trucks used indoors?
296-307-42527 How must LP-gas-fueled vehicles be garaged?
296-307-430 Storage of containers awaiting use or resale.
296-307-43001 What does this section cover?
296-307-43003 What general requirements apply to storage of containers?
296-307-43005 How must containers be stored within buildings frequented
by the public?
296-307-43007 How must containers be stored in buildings not frequented
by the public?
296-307-43009 How must containers be stored within special buildings
or rooms?
296-307-43011 How must containers be stored outdoors?
296-307-43013 What fire protection must be provided for stored containers?
296-307-435 LP-gas system installations on commercial vehicles.
296-307-43501 What does this section cover?
296-307-43503 How must containers be constructed?
296-307-43505 What is the maximum capacity allowed for LP-gas installations
on commercial vehicles?
296-307-43507 Where must systems be located?
296-307-43509 What requirements apply to valves and accessories?
296-307-43511 What requirements apply to to safety devices?
296-307-43513 What types of systems may be used on commercial vehicles?
296-307-43515 What requirements apply to enclosures and mountings?
296-307-43517 What requirements apply to piping, tubing, and fittings?
296-307-43519 What requirements apply to appliances?
296-307-43521 What general precautions must be followed for LP-gas
system installations on commercial vehicles?
296-307-43523 How must containers be charged?
296-307-43525 What fire protection must be provided for mobile cook
units?
296-307-440 LP-gas service stations?
296-307-44001 What does this section cover?
296-307-44003 How must storage containers be designed and classified?
296-307-44005 What requirements apply to valves and accessories?
296-307-44007 What requirements apply to safety devices?
296-307-44009 What is the maximum capacity allowed for containers?
296-307-44011 How must storage containers be installed?
296-307-44013 What equipment must be protected against tampering?
296-307-44015 What requirements apply to the transport truck unloading
point?
296-307-44017 What requirements apply to piping, valves, and fittings?
296-307-44019 What requirements apply to pumps and accessory equipment?
296-307-44021 What requirements apply to LP-gas dispensing devices?
296-307-44023 Is smoking allowed at LP-gas service stations?
296-307-44025 What fire protection must be provided at LP-gas service
stations?
WAC 296-307-410 Storage
and handling of liquefied petroleum gases.
WAC 296-307-41003
Which LP-gas installations are not covered by this part?
(1) This part does not apply to:
(a) LP-gas refrigerated storage systems;
(b) LP-gas used with oxygen;
(c) LP-gas used in utility gas plants (covered by the National Fire
Protection Association Standard for the Storage and Handling of Liquefied
Petroleum Gases at Utility Gas Plants, NFPA No. 59-1968);
(d) Low-pressure (less than 1/2 pound per square inch or 14 inches
water column) LP-gas piping systems, and the installation and operation
of residential and commercial appliances supplied through such systems.
The National Fire Protection Association Standard for the Installation
of Gas Appliances and Gas Piping, NFPA 54-1969 apply to these systems.
(2) LP-gas installations, equipment, and appliances that met the requirements
of the National Fire Protection Association Standard for the Storage and
Handling of Liquefied Petroleum Gases NFPA No. 58-1972, 1973 at the time
of manufacture or installation may be used if they do not create a hazard
to employees.
“Adequate ventilation,” for fire prevention during normal operation,
means the concentration of the gas in a gas-air mixture does not exceed
25% of the lower flammable limit.
“Containers” means all vessels, such as tanks, cylinders, or drums,
used to transport or store LP-gases.
“DOT” means the federal Department of Transportation.
“DOT container” means a container that meets DOT regulations.
“DOT cylinder” means a cylinder that meets DOT regulations.
“DOT regulations/requirements/specifications” means the DOT regulations
of 49 CFR part 178.
“Liquefied petroleum gases” and “LP-gas” means any material
that is composed mostly of any of the following: Hydrocarbons, or mixtures
of them; propane; propylene; butanes (normal butane or iso-butane); and
butylenes.
“PSIA” pounds per square inch absolute.
“PSIG” means pounds per square inch gauge.
“Systems” means an assembly of the container or containers, major
devices such as vaporizers, safety-relief valves, excess flow valves,
regulators, and piping connecting such parts.
“Vaporizer-burner” means an integral vaporizer-burner unit, dependent
upon the heat generated by the burner to vaporize the liquid used for
dehydrators or dryers.
You must ensure that all LP-gas is odorized by an approved agent to
indicate by distinct odor, the presence of gas down to concentration in
air of a maximum of 1/5 the lower limit of flammability.
Exception: Odorization is not required if it will
create a hazard in further processing, or if it serves no useful purpose
as a warning agent.
Note: The odorization requirement may be met by
using 1.0 pounds of ethyl mercaptan, 1.0 pounds of thiophene, or 1.4 pounds
of amyl mercaptan per ten thousand gallons of LP-gas. You may use any
odorant and quantity that meets the requirements of this section.
(1) Each system of DOT containers must have approved container valves,
connectors, manifold valve assemblies, and regulators.
(2) Each non-DOT system using containers of 2,000 gallons or less water
capacity, must have a container assembly, one or more regulators, and
other necessary parts. The entire system, or the container assembly with
the regulators, must be individually listed by a nationally recognized
testing laboratory.
“Container assembly” means the container and fittings for all
openings, including shut-off vales, excess flow valves, liquid-level gauging
devices, safety-relief devices, and protective housing.
(3) In systems using containers of over 2,000 gallons water capacity,
each regulator, container, valve, excess flow valve, gauging device, and
relief valve, must be listed by a nationally recognized testing laboratory.
(4) All DOT containers must be constructed, tested, and stamped according
to the DOT specifications effective at the date of their manufacture.
WAC 296-307-41011
What construction and test requirements must containers meet?
(1) Containers must be designed, constructed, and tested according to
the Rules for Construction of Unfired Pressure Vessels, section VIII,
Division 1, American Society of Mechanical Engineers (ASME) Boiler and
Pressure Vessel Code, 1968 edition, unless otherwise specified.
(2) Containers constructed according to the 1949 and earlier editions
of the ASME Code are exempt from U-2 through U-10 and U-19 of the code.
Containers constructed according to U-70 in the 1949 and earlier editions
do not meet the requirements of this section.
(3) Containers designed, constructed, and tested prior to July 1, 1961,
according to the Code for Unfired Pressure Vessels for Petroleum Liquids
and Gases, 1951 edition with 1954 Addenda, of the American Petroleum Institute
and the American Society of Mechanical Engineers are considered in compliance.
Containers constructed according to API-ASME Code do not have to comply
with section I or with the appendix to section I. W-601 through W-606
in the 1943 and earlier editions do not apply.
(1) You must ensure that all welding to the shell, head, or any other
part of the container subject to internal pressure, meets the requirements
of the code under which the tank was fabricated. You may weld on saddle
plates, lugs, or brackets attached to the container by the tank manufacturer.
(2) When you must repair or modify DOT containers by welding, you must
return the container to a qualified manufacturer, making containers of
the same type, to make the repair or modification according to DOT regulations.
(1) You must ensure that containers are marked according to DOT regulations
or with the following:
(a) Indication that the container meets the requirements of
the code under which it is constructed, and all marks required
by that code.
(b) Indication whether the container is designed for underground
or aboveground installation or both. If intended for both and
different style hoods are provided, the marking must indicate
the proper hood for each type of installation.
(c) The name and address of the supplier of the container,
or with the trade name of the container.
(d) The water capacity of the container in pounds or gallons,
United States standard.
(e) The pressure in psig, for which the container is designed.
(f) The wording “This container must not contain a product
with a vapor pressure greater than psig at 100°F.”
(g) The tare weight, for containers with a water capacity of
three hundred pounds or less.
(h) Indication of the maximum fill level for liquid at temperatures
between 20°F and 130°F. Markings must be in maximum increments
of 20°F. This marking may be located on the liquid level gauging
device.
Exception: Containers provided with fixed
maximum level indicators or that are filled by weighing are exempt
from this requirement.
(i) The outside surface area in square feet.
(2) The markings must be on a metal nameplate attached to the container
so that it is visible after the container is installed.
(3) When LP-gas and one or more other gases are stored or used in the
same area, the containers must be marked to identify their content. Marking
must be according to American National Standard Z48.1-1954, “Method of
Marking Portable Compressed Gas Containers to Identify the Material Contained.”
(d) LP-gas fueled industrial trucks that meet the requirements of WAC
296-307-42525;
(e) LP-gas fueled vehicles garaged according to WAC 296-307-42527;
or
(f) Containers awaiting use or resale when stored according to WAC
296-307-430.
(2) Each individual container is located away from the nearest important
building, group of buildings, or line of adjoining property that may be
built on, according to Table U-1.
TABLE U-1
Minimum Distances
Water capacity
per container
Containers
Underground Aboveground
Between above-ground
containers
Less than 125
galsa
10 feet
None
None
125-250 gals
10 feet
10 feet
None
251-500 gals
10 feet
10 feet
3 feet
501-2,000 gals
25 feetb
25 feetb
3 feet
2,001-30,000
gals
50 feet
50 feet
5 feet
30,001-70,000
gals
50 feet
75 feet
1/4 sum of diameters
of adjacent containers
70,001-90,000
gals
50 feet
100 feet
1/4 sum of diameters
of adjacent containers
(a) If the total water capacity of a multicontainer installation at
a consumer site is 501 gallons or more, the minimum distance must comply
with this table, applying the aggregate capacity instead of the capacity
per container. For multiple installations, installations must be at
least twenty-five feet apart. Do not apply the minimum distances between
aboveground containers to such installations.
(b) Distance requirements may be reduced to 10 feet for a single container
of 1200 gallons water capacity or less, if the container is at least
25 feet from any other LP-gas container of more than 125 gallons water
capacity.
(c) In buildings devoted exclusively to gas manufacturing and distributing
operations, the distances may be reduced if no containers of more than
500 gallons water capacity are located closer than ten feet to gas manufacturing
and distributing buildings.
(3) Containers installed for use must not be stacked one above the other.
(4) In industrial installations involving containers of 180,000 gallons
total water capacity or more, where serious exposures from the container
to adjacent properties are common, firewalls or other means of protection
designed and constructed according to good engineering practices are required.
(5) Readily ignitible material such as weeds and long dry grass is removed
within ten feet of any container.
(6) The minimum separation between LP-gas containers and flammable liquid
tanks is twenty feet; the minimum separation between a container and the
centerline of the dike is ten feet.
Exception: This does not apply when LP-gas containers
of 125 gallons or less capacity are installed adjacent to Class III flammable
liquid tanks of 275 gallons or less capacity.
(7) The accumulation of flammable liquids under adjacent LP-gas containers
is prevented by a means such as diking, diversion curbs, or grading.
(8) When dikes are used with flammable liquid tanks, no LP-gas containers
are located within the diked area.
WAC 296-307-41019
What requirements apply to valves and accessories?
(1) Valves, fittings, and accessories connected directly to the container
including primary shut-off valves, must have a rated working pressure
of at least 250 psig and must be of material and design suitable for LP-gas
service. The use of cast iron for container valves, fittings, and accessories
is prohibited. Container valves may be made of malleable or nodular iron.
(2) Connections to containers must have shut-off valves located as close
to the container as practical.
Exception: This does not apply to safety-relief
connections, liquid level gauging devices, and plugged openings.
(3) All required excess flow valves must close automatically at the rated
flows of vapor or liquid specified by the manufacturer. The connections,
lines, valves, and fittings must have a greater capacity than the rated
flow of the excess flow valve.
(4) Liquid level gauging devices that are constructed so that outward
flow is a maximum of that passed by a No. 54 drill size opening may be
installed without excess flow valves.
(5) Openings from container or through fittings attached directly on
container to which pressure gauge connection is made, need not have shut-off
or excess flow valves if such openings are restricted to not larger than
No. 54 drill size opening.
(6) Required excess flow and back pressure check valves must be located
inside the container or outside where the line enters the container. When
located outside, the installation must be made to prevent any stress beyond
the excess flow or back pressure check valve from causing a break between
the container and the valve.
Exception: This does not apply to systems using
containers with a water capacity greater than 2-1/2 pounds (nominal one
pound LP-gas capacity).
(7) Excess flow valves must be designed with a bypass that is a maximum
of No. 60 drill size opening to allow equalization of pressures.
(8) Containers of more than 30 gallons water capacity and less than 2,000
gallons water capacity, filled on a volumetric basis, and manufactured
after December 1, 1963, must be equipped for filling into the vapor space.
WAC 296-307-41021
What requirements apply to piping, tubing, and fittings?
(1) Pipe must be wrought iron or steel (black or galvanized), brass,
copper, or aluminum alloy. Aluminum alloy pipe must be at least Schedule
40 according to the specifications for Aluminum Alloy Pipe, ANSI H38.7-1969
(ASTM, B241-1969), and must be suitably marked at each end of each length
indicating compliance with ANSI specifications. Alloy 5456 is prohibited.
Exception: This does not apply to piping for LP-gas
used as a motor fuel or to piping on commercial vehicles.
(2) Aluminum alloy pipe must be protected against external corrosion
whenever:
(a) It is in contact with dissimilar metals other than galvanized steel;
or
(b) Its location is subject to repeated wetting by such liquids as
water (except rain water), detergents, sewage, or leaking from other
piping; or
(c) It passes through flooring, plaster, masonry, or insulation.
Galvanized sheet steel or pipe, galvanized inside and out, are considered
suitable protection.
(3) Aluminum pipe must be three-fourths inch nominal and shall not be
used for pressures exceeding 20 psig. Aluminum alloy pipe must not be
installed within six inches of the ground.
(a) Vapor piping with operating pressures not exceeding 125 psig must
be suitable for a working pressure of at least 125 psig. Pipe must be
at least Schedule 40 ASTM A-53-69, Grade B Electric Resistance Welded
and Electric Flash Welded Pipe or equal.
(b) Vapor piping with operating pressures over 125 psig and all liquid
piping must be suitable for a working pressure of at least 250 psig.
Pipe must be at least Schedule 80 if joints are threaded or threaded
and back welded. At least Schedule 40 (ASTM A-53-1969 Grade B Electric
Resistance Welded and Electric Flash Welded Pipe or equal) must be used
if joints are welded, or welded and flanged.
(4) Tubing must be seamless copper, brass, steel, or aluminum alloy.
Copper tubing must be of Type K or L or equivalent as covered in the Specification
for Seamless Copper Water Tube, ANSI H23.1-1970 (ASTM B88-1969). Aluminum
alloy tubing must be of Type A or B or equivalent as covered in Specification
ASTM B210-1968 and must be suitably marked every 18 inches indicating
compliance with ASTM specifications. The minimum nominal wall thickness
of copper tubing and aluminum alloy tubing must be as specified in Table
U-2 and Table U-3.
TABLE U-2
Wall Thickness of Copper Tubing1
Note: The standard tube size is one-eighth inch smaller
than its nominal outside diameter.
Standard
size (inches)
Nominal
O.D. (inches)
Nominal
wall thickness (inches)
Type K
Type L
1/4
0.375
0.035
0.030
3/8
0.500
0.049
0.035
1/2
0.625
0.049
0.040
5/8
0.750
0.049
0.042
3/4
0.875
0.065
0.045
1
1.125
0.065
0.050
1 1/4
1.375
0.065
0.055
1 1/2
1.625
0.072
0.060
2
2.125
0.083
0.070
1Based
on data in Specification for Seamless Copper Water Tubing, ANSI
H23.1-1970 (ASTM B-88-69).
TABLE U-3
Wall Thickness of Aluminum Alloy Tubing1
Outside
diameter (inches)
Nominal
wall thickness (inches)
Type A
Type B
3/8
0.035
0.049
1/2
0.035
0.049
5/8
0.042
0.049
3/4
0.049
0.058
1Based
on data in Standard Specification for Aluminum-Alloy Drawn Seamless
Coiled Tubes for Special Purpose Applications, ASTM B210-68.
(5) Aluminum alloy tubing must be protected against external corrosion
whenever:
(a) It is in contact with dissimilar metals other than galvanized steel;
or
(b) Its location is subject to repeated wetting by liquids such as
water (except rainwater), detergents, sewage, or leakage from other
piping; or
(c) It passes through flooring, plaster, masonry, or insulation.
Galvanized sheet steel or pipe, galvanized inside and out, are considered
suitable protection.
(6) The maximum outside diameter for aluminum alloy tubing must be three-fourths
inch and must not be used for pressures exceeding 20 psig. Aluminum alloy
tubing installed within six inches of the ground is prohibited.
(7) In systems where the gas in liquid form enters the building without
pressure reduction, only heavy walled seamless brass or copper tubing
with an internal diameter a maximum of 3/32 inch, and a wall thickness
of at least 3/64 inch shall be used.
Exception: This requirement does not apply to research
and experimental laboratories, buildings or separate fire divisions of
buildings used exclusively for housing internal combustion engines, and
to commercial gas plants or bulk stations where containers are charged,
nor to industrial vaporizer buildings, nor to buildings, structures, or
equipment under construction or undergoing major renovation.
(8) Pipe joints must be screwed, flanged, welded, soldered, or brazed
with a material having a melting point over 1,000°F. Joints on seamless
copper, brass, steel, or aluminum alloy gas tubing shall be made by approved
gas tubing fittings, or soldered or brazed with a material having a melting
point over 1,000°F.
(9) For operating pressures of 125 psig or less, fittings must be designed
for a pressure of at least 125 psig. For operating pressures above 125
psig, fittings must be designed for a minimum of 250 psig.
(10) Threaded cast iron pipe fittings are prohibited. Aluminum alloy
fittings must be used with aluminum alloy pipe and tubing. Insulated fittings
must be used where aluminum alloy pipe or tubing connects with a dissimilar
metal. You may use malleable, nodular, or higher strength gray iron for
fittings.
Note: Strainers, regulators, meters, compressors,
pumps, etc., are not to be considered as pipe fittings.
(11) All materials such as valve seats, packing, gaskets, diaphragms,
etc., must be resistant to the action of LP-gas under the service conditions
to which they are subjected.
(12) All piping, tubing, or hose must be tested after assembly and proved
free from leaks at least normal operating pressures. After installation,
piping and tubing of all domestic and commercial systems must be tested
and proved free of leaks using a manometer or equivalent device that will
indicate a drop in pressure. Test made by flame is prohibited.
(13) You must ensure that piping allows for expansion, contraction, jarring,
and vibration, and settling. You may use flexible connections.
(14) Piping outside buildings may be buried, aboveground, or both, but
must be well supported and protected against physical damage. Where soil
conditions warrant, all piping must be protected against corrosion. Where
condensation may occur, the piping must be pitched back to the container,
or you must provide a means for revaporization of the condensate.
(1) Hose shall be fabricated of materials that are resistant to the action
of LP-gas in the liquid and vapor phases. If wire braid is used for reinforcing
the hose, it must be of corrosion-resistant material such as stainless
steel.
(2) Hose subject to container pressure must be marked “LP-gas” or “LPG”
at not greater than ten-foot intervals.
(3) Hose subject to container pressure must be designed for a bursting
pressure of not less than 1,250 psig.
(4) Hose subject to container pressure must be listed by a nationally
recognized testing laboratory.
(5) Hose connections subject to container pressure must be able to withstand,
without leaking, a test pressure of not less than 500 psig.
(6) Hose and hose connections on the low-pressure side of the regulator
or reducing valve must be designed for a bursting pressure of not less
than 125 psig or five times the set pressure of the relief devices protecting
that portion of the system, whichever is higher.
(7) Hose may be used on the low-pressure side of regulators to connect
to other than domestic and commercial gas appliances under the following
conditions:
(a) The appliances connected with hose are portable and need a flexible
connection.
(b) For use inside buildings, the hose is of minimum practical length,
but is a maximum of six feet. Hose must not extend from one room to
another, nor pass through any walls, partitions, ceilings, or floors.
Such hose must not be concealed from view or used in a concealed location.
Exception: For use outside of buildings, the hose
may exceed this length but must be kept as short as practical.
(c) The hose must be approved and must not be used where it may be
exposed to temperatures above 125°F. The hose must be securely connected
to the appliance. Rubber slip ends are prohibited.
(d) The shut-off valve for an appliance connected by hose must be in
the metal pipe or tubing and not at the appliance end of the hose. When
shut-off valves are installed close to each other, precautions must
be taken to prevent operation of the wrong valve.
(e) Hose used for connecting to wall outlets must be protected from
physical damage.
(1) Every container except those constructed according to DOT
specifications and every vaporizer (except motor fuel vaporizers
and vaporizers described in WAC
296-307-41029(3) and 296-307-42007
(6)(a) whether heated by artificial means or not, must have one
or more safety-relief valves of spring-loaded or equivalent type.
These valves must be arranged to afford free vent to the outer
air with discharge not less than five feet horizontally away from
any opening into the building that is below such discharge. The
rate of discharge must be according to the requirements of subsection
(2) or (4) of this section.
(2) Minimum required rate of discharge in cubic feet per minute of air
at one hundred twenty percent of the maximum permitted start to discharge
pressure for safety-relief valves to be used on containers other than
those constructed according to DOT specification must be as follows:
Surface
area Flow rate sq. ft. CFM air
Surface
area Flow rate sq. ft. CFM air
Surface
area Flow rate sq. ft. CFM air
20 or less
626
170
3,620
550
9,470
25
751
175
3,700
600
10,170
30
872
180
3,790
650
10,860
35
990
185
3,880
700
11,550
40
1,100
190
3,960
750
12,220
45
1,220
195
4,050
850
13,540
50
1,330
200
4,130
900
14,190
55
1,430
210
4,300
950
14,830
60
1,540
220
4,470
1,000
15,470
65
1,640
230
4,630
1,050
16,100
70
1,750
240
4,800
1,100
16,720
75
1,850
250
4,960
1,150
17,350
80
1,950
260
5,130
1,200
17,960
85
2,050
270
5,290
1,250
18,570
90
2,150
280
5,450
1,300
19,180
95
2,240
290
5,610
1,350
19,780
100
2,340
300
5,760
1,400
20,380
105
2,440
310
5,920
1,450
20,980
110
2,530
320
6,080
1,500
21,570
115
2,630
330
6,230
1,550
22,160
120
2,720
340
6,390
1,600
22,740
125
2,810
350
6,540
1,650
23,320
130
2,900
360
6,690
1,700
23,900
135
2,990
370
6,840
1,750
24,470
140
3,080
380
7,000
1,800
25,050
145
3,170
390
7,150
1,850
25,620
150
3,260
400
7,300
1,900
26,180
155
3,350
450
8,040
1,950
26,750
160
3,440
500
8,760
2,000
27,310
165
3,530
Surface area = total outside surface area of container in square feet.
(3) When the surface area is not stamped on the name plate or when the
marking is not legible, calculate the area with one of the following formulas:
Hemispherical heads: Area = (overall length) X (outside diameter)
X 3.1416.
Other than hemispherical heads: Area = (overall length) + 0.3 (outside
diameter) X (outside diameter ) X 3.1416.
Note: This formula is not exact, but will give results
within the limits of practical accuracy for the sole purpose of sizing
relief valves.
Spherical container: Area = (outside diameter)2 X 3.1416.
Flow rate: CFM air = required flow capacity in cubic feet per minute
of air at standard conditions, 60°F and atmospheric pressure (14.7
psia).
For containers with total outside surface area greater than 2,000 sq.
ft., the formula is: Flow rate CFM air = 53.632 A0.82 where A = outside
surface area of the container in square feet.
Valves not marked “air” have flow rate marking in cubic feet per minute
of LP-gas. These can be converted to ratings in cubic feet per minute
of air by multiplying the LP-gas ratings by factors listed below. Air
flow ratings can be converted to ratings in cubic feet per minute of LP-gas
by dividing the air ratings by the factors listed below.
Air Conversion
Factors
Container
Type
100
125
150
175
200
Air Conversion
Factor
1.162
1.142
1.113
1.078
1.010
(4) The minimum required rate of discharge for safety-relief valves for
LP-gas vaporizers (steam heated, water heated, and direct fired) must
be determined as follows:
(a) Obtain the total surface area by adding the surface area of vaporizer
shell in square feet directly in contact with LP-gas and the heat exchanged
surface area in square feet directly in contact with LP-gas.
(b) Obtain the minimum required rate of discharge in cubic feet of
air per minute, at 60°F and 14.7 psia from subsection (2) of this section,
for this total surface area.
(5) Container and vaporizer safety-relief valves must be set to start
to discharge, with relation to the design pressure of the container, according
to the following:
Containers
Minimum
(Percent)
Maximum
(Percent)
ASME Code; Par.
U-68, U-69-1949 and earlier editions.
*Manufacturers
of safety-relief valves are allowed a plus tolerance not exceeding
10% of the set pressure marked on the valve.
(6) Safety-relief devices used with systems employing non-DOT containers
must be constructed to discharge at not less than the rates shown in subsection
(2) of this section, before the pressure is in excess of 120% of the maximum
(not including the 10% referred to in subsection (5) of this section)
permitted start-to-discharge pressure setting of the device.
(7) In high temperature areas, you must use a lower vapor pressure product
or a higher designed pressure vessel to prevent the safety valves from
opening. The tanks may be protected by cooling devices such as spraying,
shading, or other means.
(8) Safety-relief valves must be arranged to minimize tampering. For
external pressure setting or adjustment, the relief valves must have an
approved sealable adjustment.
(9) Shut-off valves are prohibited between safety-relief devices and
the container, equipment, or piping.
Exception: A shut-off valve may be used where the
arrangement of the valve allows the required capacity flow through the
safety-relief device.
(10) Safety-relief valves must have direct communication with the vapor
space of the container.
(11) Each safety-relief valve must be plainly and permanently marked
with the following:
(a) Container type of the pressure vessel on which the valve is designed
to be installed;
(b) The pressure in psig at which the valve is set to discharge;
(c) The actual rate of discharge of the valve in cubic feet per minute
of air at 60°F and 14.7 psia; and
(d) The manufacturer's name and catalog number.
For example: T200-250-4050 AIR: Indicates that
the valve is suitable for use on a Type 200 container, that it is set
to start to discharge at 250 psig; and that its rate of discharge is
4,050 cubic feet per minute of air.
(12) Safety-relief valve assemblies and their connections must be large
enough to provide the required rate of flow for the container on which
they are installed.
(13) A hydrostatic relief valve must be installed between each pair of
shut-off valves on LP-gas liquid piping. The start-to-discharge pressure
setting of such relief valves must be a maximum of 500 psig. The minimum
setting on relief valves installed in piping connected to non-DOT containers
shall be 140% of the container relief valve setting. For piping connected
to DOT containers, the minimum must be 400 psig. The relief valve should
not be installed in the pump discharge piping if the same protection can
be provided by installing the relief valve in the suction piping. The
start-to-discharge pressure setting of such a relief valve, if installed
on the discharge side of a pump, must exceed the maximum pressure permitted
by the recirculation device in the system.
(14) The discharge from any safety-relief device must not terminate in
or beneath any building.
(15) Container safety-relief devices and regulator relief vents must
be located at least five feet in any direction from air openings into
sealed combustion system appliances or mechanical ventilation air intakes.
WAC 296-307-41027
How must indirect fired vaporizers be constructed and installed?
Indirect fired vaporizers utilizing steam, water, or other heating medium
must be constructed and installed according to the following:
(1) Vaporizers must be constructed according to the requirements of WAC
296-307-41011 and must be permanently marked as follows:
(a) With the code marking signifying the specifications to which the
vaporizer is constructed;
(b) With the allowable working pressure and temperature for which the
vaporizer is designed;
(c) With the sum of the outside surface area and the inside heat exchange
surface area expressed in square feet; and
(d) With the name or symbol of the manufacturer.
(2) Vaporizers with an inside diameter of six inches or less exempted
by the ASME Unfired Pressure Vessel Code, Section VIII of the ASME Boiler
and Pressure Vessel Code, 1968, must have a design pressure of at least
250 psig and need not be permanently marked.
(3) Heating or cooling coils installed inside a storage container are
prohibited.
(4) Vaporizers may be installed in buildings, rooms, sheds, or lean-tos
used exclusively for gas manufacturing or distribution, or in other light,
noncombustible structures that are well ventilated near the floor line
and roof.
Exception: When vaporizing and/or mixing equipment
is in a structure not used exclusively for gas manufacturing or distribution,
the structure or room must be separated from the remainder of the building.
The separation must be a wall designed to withstand a static pressure
of at least 100 pounds per square foot. This wall must have no openings
or pipe or conduit passing through it. Such structure or room must have
adequate ventilation and must have a roof or at least one exterior wall
of lightweight construction.
(5) All DOT vaporizers must have, at or near the discharge, a safety-relief
valve providing an effective rate of discharge according to WAC
296-307-41025.
(6) The heating medium lines into and out of the vaporizer must have
a mechanism to prevent the flow of gas into the heat systems in the event
of tube rupture in the vaporizer. Vaporizers must have an automatic means
to prevent liquid from passing through the vaporizers to the gas discharge
piping.
(7) The device that supplies heat to produce steam, hot water, or other
heat may be installed in a building, compartment, room, or lean-to ventilated
near the floorline and roof to the outside. The device must be separated
from all compartments or rooms containing LP-gas vaporizers, pumps, and
central gas mixing devices by a wall designed to withstand a static pressure
of at least 100 pounds per square foot. This wall must have no openings
or pipes or conduit passing through it.
Exception: This requirement does not apply to the
domestic water heaters that may supply heat for a vaporizer in a domestic
system.
(8) Gas-fired heating systems supplying heat exclusively for vaporization
must have automatic safety devices to shut off the flow of gas to main
burners, if the pilot light should fail.
(9) Vaporizers may be an integral part of a fuel storage container directly
connected to the liquid section or gas section or both.
(10) Fusible plugs are prohibited on vaporizers.
(11) Vaporizer houses must not have unprotected drains to sewers or sump
pits.
WAC 296-307-41029
How must atmospheric vaporizers be constructed and installed?
Atmospheric vaporizers using heat from the ground or surrounding air
must be installed as follows:
(1) Buried underground; or
(2) Located inside the building near where the pipe enters the building,
if the capacity of the unit does not exceed one quart;
(3) Vaporizers of less than one quart capacity heated by the ground or
surrounding air, may be installed without safety-relief valves if tests
show that the assembly is safe.
WAC 296-307-41031
How must direct gas-fired vaporizers be constructed and installed?
Direct gas-fired vaporizers must be constructed, marked, and installed
as follows:
(1) According to the requirements of the American Society of Mechanical
Engineers Boiler and Pressure Vessel Code, 1968, that apply to the maximum
working conditions for which the vaporizer is designed.
(2) With the name of the manufacturer; rated Btu input to the burner;
the area of the heat exchange surface in square feet; the outside surface
of the vaporizer in square feet; and the maximum vaporizing capacity in
gallons per hour.
(3) Vaporizers may be connected to the liquid section or the gas section
of the storage container, or both. The container must have a manually
operated valve in each connection that completely shuts off when desired,
all flow of gas or liquid from container to vaporizer.
(4) Vaporizers with a maximum capacity of 35 gallons per hour must be
located at least 5 feet from container shut-off valves. Vaporizers more
than 35 gallon capacity but a maximum of 100 gallons per hour must be
located at least 10 feet from the container shut-off valves. Vaporizers
having a capacity greater than 100 gallons per hour must be located at
least 15 feet from container shut-off valves.
(5) Vaporizers may be installed in buildings, rooms, housings, sheds,
or lean-tos used exclusively for vaporizing or mixing of LP-gas. Vaporizing
housing structures must be noncombustible, and well ventilated near the
floorline and the highest point of the roof. When vaporizer and/or mixing
equipment is located in a structure or room attached to or within a building,
such structure or room must be separated from the remainder of the building
by a wall designed to withstand a static pressure of at least 100 pounds
per square foot. This wall must have no openings or pipes or conduit passing
through it. The structure or room must have adequate ventilation, and
a roof or at least one exterior wall of lightweight construction.
(6) Vaporizers must have at or near the discharge, a safety-relief valve
providing an effective rate of discharge according to WAC
296-307-41025. The relief valve must be located where it is
not subjected to temperatures over 140°F.
(7) Vaporizers must have suitable automatic means to prevent liquid passing
from the vaporizer to the gas discharge piping of the vaporizer.
(8) Vaporizers must have means for manually turning off the gas to the
main burner and pilot.
(9) Vaporizers must have automatic safety devices to shut off the flow
of gas to main burners if the pilot light should fail. When the flow through
the pilot exceeds 2,000 Btu per hour, the pilot also must have an automatic
safety device to shut off the flow of gas to the pilot should the pilot
flame be extinguished.
(10) Pressure regulating and pressure reducing equipment located within
10 feet of a direct fired vaporizer must be separated from the open flame
by an airtight noncombustible partition.
(11) Except as provided in subsection (5) of this section, the following
minimum distances must be maintained between direct fired vaporizers and
the nearest important building, group of buildings, or line of adjoining
property that may be built on:
(a) Ten feet for vaporizers with a vaporizing capacity of 15 gallons
per hour or less;
(b) Twenty-five feet for vaporizers with a vaporizing capacity of 16-100
gallons per hour;
(c) Fifty feet for vaporizers with a vaporizing capacity over 100 gallons
per hour.
(12) Direct fired vaporizers must not raise the product pressure above
the design pressure of the vaporizer equipment or above the pressure shown
in the second column of Table U-8.
(13) Fusible plugs are prohibited on vaporizers.
(14) Vaporizers must not have unprotected drains to sewers or sump pits.
WAC 296-307-41033
How must direct gas-fired tank heaters be constructed and installed?
Direct gas-fired tank heaters must be constructed and installed as follows:
(1) Direct gas-fired tank heaters, and tanks to which they are applied,
must only be installed aboveground.
(2) Tank heaters must be permanently marked with the name of the manufacturer,
the rated Btu input to the burner, and the maximum vaporizing capacity
in gallons per hour.
Note: Tank heaters may be an integral part of a
fuel storage container directly connected to the container liquid section,
or vapor section, or both.
(3) Tank heaters must have a means for manually turning off the gas to
the main burner and pilot.
(4) Tank heaters must have an automatic safety device to shut off the
flow of gas to main burners, if the pilot light should fail. When flow
through pilot exceeds 2,000 Btu per hour, the pilot also must have an
automatic safety device to shut off the flow of gas to the pilot should
the pilot flame be extinguished.
(5) Pressure regulating and pressure reducing equipment if located within
ten feet of a direct fired tank heater must be separated from the open
flame by a substantially airtight noncombustible partition.
(6) The following minimum distances must be maintained between a storage
tank heated by a direct fired tank heater and the nearest important building,
group of buildings, or line of adjoining property that may be built on:
(a) Ten feet for storage containers of less than 500 gallons water
capacity;
(b) Twenty-five feet for storage containers of 500-1,200 gallons water
capacity;
(c) Fifty feet for storage containers of over 1,200 gallons water capacity.
(7) No direct fired tank heater may raise the product pressure within
the storage container over 75% of the pressure in the second column of
Table U-8.
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