ASTM F1508-96(2021)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:F1508 −96 (Reapproved 2021) An American National Standard
Standard Specification for
Angle Style, Pressure Relief Valves for Steam, Gas, and
Liquid Services
This standard is issued under the fixed designation F1508; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Stainless and Alloy, for Pressure-Containing Parts, Suit-
able for High-Temperature Service
1.1 This specification covers spring-loaded, angle style,
A227/A227M Specification for Steel Wire, Cold-Drawn for
pressure relief valves for steam, gas, and liquid system
Mechanical Springs
applications (excluding boiler safety and hydraulic system
A229/A229M Specification for Steel Wire, Quenched and
relief valves).
Tempered for Mechanical Springs
1.2 The values stated in inch-pound units are to be regarded
A231/A231M Specification for Chromium-Vanadium Alloy
as standard. No other units of measurement are included in this
Steel Spring Wire
standard.
A276 Specification for Stainless Steel Bars and Shapes
1.3 This international standard was developed in accor- A313/A313M Specification for Stainless Steel Spring Wire
dance with internationally recognized principles on standard-
A351/A351M Specification for Castings, Austenitic, for
ization established in the Decision on Principles for the Pressure-Containing Parts
Development of International Standards, Guides and Recom-
A479/A479M Specification for Stainless Steel Bars and
mendations issued by the World Trade Organization Technical Shapes for Use in Boilers and Other Pressure Vessels
Barriers to Trade (TBT) Committee.
A494/A494M Specification for Castings, Nickel and Nickel
Alloy
2. Referenced Documents
A689 Specification for Carbon and Alloy Steel Bars for
Springs
2.1 ASTM Standards:
B21/B21M Specification for Naval Brass Rod, Bar, and
A105/A105M Specification for Carbon Steel Forgings for
Shapes
Piping Applications
B61 Specification for Steam or Valve Bronze Castings
A125 Specification for Steel Springs, Helical, Heat-Treated
B62 Specification for Composition Bronze or Ounce Metal
A182/A182M Specification for Forged or Rolled Alloy and
Castings
Stainless Steel Pipe Flanges, Forged Fittings, and Valves
B148 Specification for Aluminum-Bronze Sand Castings
and Parts for High-Temperature Service
B164 Specification for Nickel-Copper Alloy Rod, Bar, and
A193/A193M Specification for Alloy-Steel and Stainless
Wire
Steel Bolting for High Temperature or High Pressure
B637 Specification for Precipitation-Hardening and Cold
Service and Other Special Purpose Applications
Worked Nickel Alloy Bars, Forgings, and Forging Stock
A194/A194M Specification for Carbon Steel, Alloy Steel,
for Moderate or High Temperature Service
and Stainless Steel Nuts for Bolts for High Pressure or
D5204 Classification System and Basis for Specification for
High Temperature Service, or Both
Polyamide-Imide (PAI) Molding and Extrusion Materials
A216/A216M SpecificationforSteelCastings,Carbon,Suit-
F467 Specification for Nonferrous Nuts for General Use
able for Fusion Welding, for High-Temperature Service
F468 Specification for Nonferrous Bolts, Hex Cap Screws,
A217/A217M Specification for Steel Castings, Martensitic
Socket Head Cap Screws, and Studs for General Use
2.2 API Standards:
This specification is under the jurisdiction of ASTM Committee F25 on Ships
API 526 Flanged Steel Safety-Relief Valves
and Marine Technology and is the direct responsibility of Subcommittee F25.11 on
API RP 520, Part 1 Recommended Practice for the Design
Machinery and Piping Systems.
and Installation of Pressure-Relieving Systems in Refin-
Current edition approved Jan. 1, 2021. Published January 2021. Originally
ɛ1
approved in 1996. Last previous edition approved in 2016 as F1508 – 96 (2016) .
eries
DOI: 10.1520/F1508-96R21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from American Petroleum Institute (API), 200 Massachusetts
the ASTM website. Avenue, NW Suite 1100 Washington, DC 20001-5571, http://www.api.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1508−96 (2021)
2.3 ASME Standard: force per square inch or a percent of the set pressure. The
ASME Boiler and Pressure Vessel Code, Section VIII accumulation and blowdown establish the operating band of
ASME B1.1 Unified Inch Screw Threads (UN, UNR, and the pressure relief valve at a particular set pressure.
UNJ Thread Forms)
3.1.4 blowdown pressure, n—the set pressure minus the
ASME B16.5 Pipe Flanges and Flanged Fittings: NPS 1/2
blowdown. Blowdown pressure is expressed in pound-force
through NPS 24 Metric/Inch Standard
per square inch gauge.
ASME B16.34 Valves — Flanged, Threaded, and Welding
3.1.5 built-up backpressure, n—thestaticdischargepressure
End
at the outlet of a pressure relief valve caused by the pressure
2.4 Federal Specifications:
drop in the discharge piping while the valve is discharging.
QQ-N-281 Nickel-Copper Alloy Bar, Rod, Plate, Sheet,
3.1.6 gagging device, n—a device, normally a screw (also
Strip, Wire, Forgings, and Structural and Special Shaped
called test gag), used to prevent the pressure relief valve from
Sections
opening during a hydrostatic pressure test of the equipment on
QQ-N-286 Nickel-Copper-AluminumAlloy, Wrought (UNS
which it is installed.
N05500)
2.5 Military Standards and Specifications: 3.1.7 inlet piping, n—when used in this specification, refers
MIL-STD-167-1 Mechanical Vibrations of Shipboard
to all piping and fittings between the source and the inlet
Equipment (Type I—Environmental and Type II— connection to the pressure relief valve.
Internally Excited)
3.1.8 instability (chatter, flutter), n—an unstable operation
MIL-STD-1330 Cleaning andTesting of Shipboard Oxygen,
of the pressure relief valve characterized by rapid seating and
Nitrogen and Hydrogen Gas Piping Systems
unseating of the disk during discharge. This hammering of the
MIL-F-1183 Fittings, Pipe, Cast Bronze, Silver Brazing,
disk on the seat can cause high loading forces, which can lead
General Specification for
to damage and rapid failure of the seating and sliding surfaces.
MIL-F-20042 Flanges, Pipe and Bulkhead, Bronze (Silver
3.1.9 maximum system operating pressure, n—the highest
Brazing)
pressure that can exist in a system, vessel, or component under
MIL-P-46122 Plastic Molding Material and Plastic Extru-
normal (noncasualty) operating conditions. This is a normal
sion Material, Polyvinylidene Fluoride Polymer and Co-
(noncasualty) pressure that the pressure relief valve is not
polymer
intended to protect against. This pressure can be the result of
MIL-R-17131 Rods, Welding, Surfacing
influences such as pump or compressor shutoff pressure,
MIL-S-901 Shock Tests, H.I. (High-Impact); Shipboard
pressure regulating valve lockup (no flow) pressure, and so
Machinery, Equipment and Systems, Requirements for
forth.
MS 16142 Boss, Gasket-Seal Straight Thread Tube Fitting,
Standard Dimensions for 3.1.10 opening pressure, n—the value of increasing inlet
MS 51840 Plug, Machine Thread, O-ring static pressure of a pressure relief valve at which there is a
measurable lift, or at which the discharge becomes continuous
2.6 Naval Sea Systems Command (NAVSEA) Drawings:
by seeing, feeling, or hearing.
803-1385884 Unions,FittingsandAdapters,ButtandSocket
Welding, 6000 PSI, WOG IPS
3.1.11 outlet piping (or discharge piping), n—when used in
803-1385943 Unions, Silver Brazing, 3000 PSI, WOG IPS,
this specification, refers to all piping and fittings between the
for UT Inspection
pressure relief valve outlet connection and the main, tank, or
803-1385946 Unions, Bronze Silver Brazing, WOG, for UT
atmosphere to which the pressure relief valve relieves.
Inspection
3.1.12 popping pressure, n—the value of increasing inlet
staticpressureatwhichthediskmovesintheopeningdirection
3. Terminology
at a faster rate as compared with the corresponding movement
3.1 Definitions:
at higher or lower pressures. It generally applies to valves with
3.1.1 accumulation, n—the increase in static pressure above
compressible fluid service such as steam, gas, and so forth.
the set pressure during discharge through the valve, when the
3.1.13 pressure relief valve, n—an automatic pressure
valve passes the rated flow. Accumulation is expressed in
relieving device actuated by the static pressure upstream of the
pound-force per square inch or as a percent of the set pressure.
valve and characterized by either rapid opening (pop action for
3.1.2 accumulation pressure, n—the set pressure plus the
gas, vapor, or steam) or gradual opening (for liquids).
accumulation. Accumulation pressure is expressed in pound-
3.1.14 primary and secondary pressure zones of pressure
force per square inch gauge.
relief valve, n—primary pressure zone refers to all portions of
3.1.3 blowdown, n—the difference between the set pressure
the pressure-containing envelope subject to inlet pressure;
and the reseating pressure. Blowdown is expressed in pound-
secondary pressure zone refers to all portions of the pressure-
containing envelope subject to outlet or discharge pressure
(includes spring housing of nonvented valves).
Available from American Society of Mechanical Engineers (ASME), ASME
International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
3.1.15 relieving capacity (also called flow capacity), n—the
www.asme.org.
pressure relief valve is defined as the quantity of pressure
Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,
Philadelphia, PA 19111-5094, http://quicksearch.dla.mil. medium relieving through the pressure relief valve at the
F1508−96 (2021)
accumulationpressure,suchaspoundperhourofsteam,gallon 5. Ordering Information
per minute of water at 70°F, or SCFM (standard cubic feet per
5.1 Ordering documentation for valves under this specifica-
minute at 60°F and 14.7 psia) of air, as applicable.
tion shall include the following information, as required, to
describe the equipment adequately.
3.1.16 set pressure, n—the value of increasing inlet static
5.1.1 ASTM designation and year of issue.
pressure at which a pressure relief valve displays one of the
5.1.2 Valve specification code (see 6.2).
operational characteristics as defined under opening pressure,
5.1.3 Quantity of valves.
or start-to-leak pressure. Set pressure is expressed in pound-
5.1.4 Maximum inlet temperature.
force per square inch gauge.
5.1.5 Set pressure.
3.1.17 set pressure range, n—the range over which the set
5.1.6 Requiredrelievingcapacity(flow)attheaccumulation
pressure can be adjusted with the installed spring.
pressure.
5.1.7 Installation limitations data, if different than specified
3.1.18 set pressure tolerance, n—the permissible plus or
in 7.9.
minus deviation from the specified set pressure. Set pressure
5.1.8 Blowdown limits, if different than specified in 7.7.
tolerance is expressed in pound-force per square inch or as a
5.1.9 Envelope dimensions, if not covered in Table 13 and
percent of the set pressure.
Table 14.
3.1.19 source, n—when used in this specification, refers to
5.1.10 Supplementary requirements, if any (see S1 through
the pressure container being protected from overpressure by
S5).
the pressure relief valve, for example, piping main, pressure
6. Valve Coding and Construction
vessel or tank, casing, and so forth.
6.1 Valves shall incorporate the design features specified in
3.1.20 start-to-leak pressure, n—the value of increasing
6.2 and 6.3.
inlet static pressure at which the first bubble occurs when a
pressure relief valve for compressible fluid service of the
6.2 Valve Specification Coding—Basicvalvedesignfeatures
resilient disk design is tested by means of air under a specified
shall be specified and recorded using the following valve
water seal on the outlet.
coding system. The valve specification code contains nine
fields of information, which describe the construction features
3.1.21 superimposedbackpressure,n—thestaticpressureon
of the valve. Each of these nine fields are further assigned their
thedischargesideofapressurereliefvalvepriortotheopening
respective codes in accordance with Tables 1-7.
of the pressure relief valve. This pressure exists where the
pressure relief valve discharges into a common pipeline shared
with other pressure sources such as pressure relief valves, or
intoapressurizedorclosedsystem.Thispressuremayhavethe
effect of changing the set pressure of the pressure relief valve.
3.1.22 top-guided valve, n—this type of valve has all the
guiding, rubbing, or contacting surfaces on the discharge side
of the seat.
4. Classification
6.3 Construction—Valve construction shall be in accor-
4.1 Pressurereliefvalvesshallbeofthefollowingtypesand
dance with the requirements specified in 6.3.1 – 6.3.19.
material grades:
6.3.1 The materials of construction for various valve com-
4.1.1 Type I—For Steam Service:
ponentsaredetailedinTable8forTypeIvalvesandTable9for
4.1.1.1 Grade A—Alloy steel construction (for steam ser-
Types II and III valves.
vice temperatures up to 1000°F) (see Table 8).
6.3.2 General Requirements—The valve shall be self-
4.1.1.2 Grade B—Carbon steel construction (for steam ser- contained, single-seated, and spring-loaded where the inlet
pressure is directly sensed under the spring-loaded disk. The
vice temperatures up to 775°F) (see Table 8).
valve shall incorporate only a single inlet and a single outlet
4.1.2 Type II—For Air, Gas Service:
connection.
4.1.2.1 Grade C—Bronze or stainless steel construction (for
air, gas service excluding oxygen) (see Table 9).
TABLE 1 Valve Type and Material Code
4.1.2.2 Grade D—Ni-Cu alloy construction (for oxygen)
Valve Classification
Valve Type and Material
(see Table 9).
Code
Valve Type Material Grade
4.1.3 Type III—For Liquid Service (except hydraulic oil):
IA 1
IB 2
4.1.3.1 Grade E—Ferrous construction (for noncorrosive
II C 3
liquids, such as fuel oil, water, steam condensate, and so forth)
II D 4
III E 5
(see Table 9).
III F 6
4.1.3.2 Grade F—Nonferrous construction (for corrosive
As specified As specified 9
liquids, such as seawater, and so forth) (see Table 9).
F1508−96 (2021)
TABLE 2 Codes for Valve Inlet/Outlet Pipe Size
Nominal valve inlet
or As
0.25 0.38 0.50 0.75 1.00 1.25 1.5 2.0 2.5 3.0 3.5 4.0 5.0 6.0 8.0 10.0
outlet pipe size, specified
in. (NPS)
Code A B C D E F G H J K L M N P R T W
TABLE 3 End Connection Codes for Valve Inlet and Outlet Ports
(2) 600 psig (for Type II, Grade C and Type III, Grade F
valves only).
NOTE1—Unlessotherwisespecifiedinthepurchaseorder(CodeW),all
(3) ASME B16.34, Class 150 pressure rating (for Type I,
ANSI flanges shall have raised faces.
Grades A and B and Type III, Grade E valves only).
NOTE 2—Unless otherwise specified in the purchased order (Code W),
6.3.4 Body Construction—The valve shall be of the angle-
all Navy flanges shall be plain and without preinserted rings.
body design. It shall be constructed so that the seat will not
Codes for Valves
becomedistortedrelativetothedisk,andvalveoperationisnot
Type I Type II Valves For Type III
adversely affected by internal pressure and temperature.
Type of End Connection
Grades Grade Grade Grade Grade
A and C D E F
6.3.5 Bonnet Construction (Spring Housing):
B
6.3.5.1 ForTypeIvalves,thebonnetshallbeattachedtothe
ANSI flanged in accordance withAA
body with bolted flanges. Type I, Grade A valves must have
ASME B16.5, Class 150
exposed spring bonnets—the discharge flow released through
ANSI flanged in accordance withBB
ASME B16.5, Class 300
the open bonnet shall be minimal. For Type II and Type III
ANSI flanged in accordance withCC
valves, the bonnet shall be attached to the body with bolted
ASME B16.5, Class 600
flanges, or a threaded union connection.
ANSI flanged in accordance with D
ASME B16.5, Class 900
6.3.5.2 For pressure-tight (nonvented) bonnet construction
ANSI flanged in accordance with E
valves (for air/gas and liquid applications), there shall be no
ASME B16.5, Class 1500
SBU, in accordance with MIL-F- FF discharge of pressure medium into the atmosphere from the
1183 (400 psi)
bonnet or from the body-to-bonnet joint.
Union-End, in accordance with G
6.3.5.3 Vented-bonnet construction valves shall incorporate
Drawing 803-1385946
(1500 psi)
a threaded vent hole in the bonnet for the discharge of pressure
Union-End, in accordance with H
medium into the atmosphere. The discharge flow released
Drawing 803-1385943
through the vent hole shall be minimal. The vent hole shall be
(3000 psi)
Union-End, in accordance with I
capable of attaching a pressure-tight MS straight-threaded tube
Drawing 803-1385884
fitting to divert the pressure relief to a distant location. The
(6000 psi)
nominal tube fitting size shall be in accordance with Table 11.
6–in. Long nipple welded K
(400 psi)
The vent hole shall be in accordance with MS 16142. Valves
6–in. Long nipple welded L
shall be furnished with a vent plug in accordance with MS
(1500 psi)
51840 to keep the dirt away and to allow hydro testing. A
6–in. Long nipple welded M
(3000 psi)
warningtaginstructingthemandatoryremovaloftheventplug
6–in. Long nipple welded N
after valve installation must also be attached to the valve vent
(6000 psi)
Navy flanged, in accordance P plug.
with MIL-F-20042, 150 lb
6.3.5.4 There shall be one bonnet for each valve body of a
Navy flanged, in accordance R
particularnominalinletsizeandpressure-temperaturerating.It
with MIL-F-20042, 250 lb
Navy flanged, in accordance T
shall be capable of housing any of the springs required to span
with MIL-F-20042, 400 lb
the applicable set pressure ranges.
As specified W W W W W
6.3.6 Internal Trim:
6.3.6.1 For Type I valves, valves shall be provided with a
threaded seat ring, which shall be welded or nickel-brazed
circumferentially to the body. The valve body shall have
sufficient metal at the seat section to permit installation of a
6.3.3 Pressure-Temperature Ratings—The pressure-
separate seat ring, if required as a service repair.When the seat
temperature ratings of a pressure relief valve consist of ratings
ring is a part of the inlet flange raised face, such as in full
for the primary and secondary pressure zones.
nozzle valves, no welding or brazing is required.
6.3.3.1 Pressure-Temperature Rating of the Primary Pres-
6.3.6.2 For Types II and III valves, the valve shall have a
sure Zone—This shall correspond to the rating of the inlet end
replaceable seat ring. The seat ring shall be either threaded-in
connection, and is given in Table 10.
or retained by a cage construction and shall be easily
6.3.3.2 Pressure-TemperatureRatingoftheSecondaryPres-
replaceable, using hand tools, after extended service.
sure Zone—The secondary pressure zone shall withstand the
higher of the following: 6.3.6.3 Thevalvedisktovalveseatsealingmustbemetalto
(1) 150 % of maximum backpressure buildup specified in metal for Type I valves and metal to nonmetal for Type II and
7.9. Type III valves.
F1508−96 (2021)
TABLE 4 Bonnet Construction Codes
Code for Type I Valve Code for Type II Valve Code for Type III Valve
Type of Bonnet
Construction Grade A Grade B Grade C Grade D Grade E Grade F
Vented bonnet not applicable AAAAA
Pressure-tight bonnet not applicable BBBBB
Open bonnet C not applicable not applicable not applicable not applicable not applicable
(exposed spring)
TABLE 5 Hand-Lifting Device Codes TABLE 8 Materials of Construction for Type I Valves
Is Hand-Lifting Name of Part Grade A Grade B
Code for Type I Code for Type II Code for Type III
Device Required
Body, bonnet, and Specification A182/A182M, Specification A105/A105M
Valves Valves Valves
With the Valve?
yoke Grade F11, F22
Specification A182/A182M,
Yes 111 Grade F11, F22
No not applicable 2 not applicable Specification A217/A217M, Specification A216/A216M,
Grade WC6, WC9 Grade WCB
Specification A217/A217M,
Grade WC1, WC6
TABLE 6 Gagging Device Codes
Specification A351/A351M,
Grade CF3, CF3M, CF8,
Is Gagging Device
Code for Type I Code for Type II Code for Type III
CF8M
Required With the
Valves Valves Valves
Metallic disk and Haynes 25 or Stellite Specifications A276,
Valve?
seat ring (wrought Stellite 6B, cast) A479/A479M, Types
Yes 111
302, 304, 316, 410, 430
No 222
Stellite 6 or an inlay of Stel- Specification A351/A351M,
lite not less than ⁄32 in. Grades CF3, CF3M, CF8,
thick. Where inlays are CF8M
used, welding rod shall be QQ-N-281, QQ-N-286
TABLE 7 Valve Envelope Dimensions Code
in accordance with Type Specification A494/A494M
Requirement to Meet Listed Envelope Dimensions Code
MIL-RCoCr-A of MIL-R-
17131 and base materials
The valve meets the envelope dimensions listed in Table 12 1
shall be one of the follow-
and Table 13.
ing:
The valve does not meet the envelope dimensions listed in 2
Specification A351/A351M,
Table 12 and Table 13.
Grade CF3, CF3M, CF8,
CF8M
Specification A276, Types
302, 304, 316, 347
Stem Specifications A276, Specifications A276,
6.3.6.4 The disk or the disk holder assembly shall be
A479/A479M, Types A479/A479M, Types
302, 304, 316, 410, 430 302, 304, 316, 410, 430
top-guided. Bottom-guided valves (also known as wing-guided
A
Springs Specification B637 (Inconel Specification A125
valves), or other construction valves where all or part of the
X750)
A
guiding surfaces are under the disk, are not permitted. Guiding Specification A227/A227M
A
Specification A229/A229M
surfaces (bushings and posts) shall have the proper hardness,
A
Specification A231/A231M
finish, concentricity, parallelism, clearances, length, and rigid-
Specification A276
A
ity to prevent binding or seizing and to ensure proper seating Specification A689
Specification A313/A313M
under all operating conditions. These alignment requirements
Specification B637 (Inconel
shall be maintained with interchangeable parts and under any
X750)
tolerance stackup. Body bolts and Specification A193/A193M, Specification A193/A193M,
nuts Grade B16 Grade B7, B16
6.3.7 Interchangeability—In no case shall the parts be
Specification A194/A194M, Specification A194/A194M,
physically interchangeable in a valve unless such parts are also
Grade 4 Grade 2H, 4
interchangeable with regard to function, performance, and
A
Electroless nickel plated (ENP) or zinc plated.
strength. Where machining is required after installation of a
seat ring or guide to maintain critical concentricity or align-
ment dimensions, detailed instructions must be provided with
each repair part. 6.3.10 Bearing Surfaces—Nut- and bolt-bearing surfaces
6.3.8 Spring—The spring shall be designed so that the full and their respective mating surfaces on the valves shall be
lift spring compression shall be no greater than 80 % of the machine finished.
nominal solid deflection. The permanent set of the spring 6.3.11 Stem Packing—A stuffing box, O-rings, or any other
(defined as the difference between the free height and height nonmetallic materials shall not be permitted on the stem/disk
measured 10 min after the spring has been compressed solid guiding surfaces.
four times at room temperature) shall not exceed 0.5 % of the 6.3.12 Hand-Lifting Device—When specified (see 6.2),
free height. Spring ends shall be squared and ground. valves shall be provided with a hand-lifting device so that they
6.3.9 Threads—Threads shall conform toASME B1.1. Pro- may be operated by hand for testing purposes with an inlet
visions shall be incorporated to prevent the accidental loosen- pressure of 75 % of the set pressure.Type I andType III valves
ing of threaded parts. Pipe threads and lock-washers shall not must be furnished with a hand-lifting device. The necessary
be used. lever or tool shall be furnished as part of the valve. For valves
F1508−96 (2021)
TABLE 9 Materials of Construction for Types II and III Valves
Name of Part Type II, Grade C Type II, Grade D Type III, Grade E Type III, Grade F
Body, bonnet, and yoke Specifications B61, B62 QQ-N-281, Specification A494/ Specification A105/A105M Specifications B61, B62
A494M
Specification A216/A216M, Specification B148, Grade 958
Grade WCB
Specifications A276/A479/ Specifications A276/A479/ QQ-N-281, Specification A494/
A479M, Types 302, 304, A479M, Types 302, 304, A494M
316, 410, 430 316, 410, 430
Specification A351/A351M, Specification A351/A351M,
Grade CF3, CF3M, CF8, Grade CF3, CF3M, CF8,
CF8M CF8M
Metallic disk and seat ring Specifications B61, B62 QQ-N-281, QQ-N-286 Specifications A276/A479/ QQ-N-281, QQ-N-286
A479M, Types 302, 304,
316, 410, 430
QQ-N-281, QQ-N-286, Specifi- Specification A494/A494M Specification A494/A494M
cation A494/A494M
Specifications A276/A479/ Specification A351/A351M,
A479M, Types 302, 304, Grade CF3, CF3M, CF8,
316, 410, 430 CF8M
Specification A351/A351M,
Grade CF3, CF3M, CF8,
CF8M
Stem QQ-N-281, QQ-N-286 QQ-N-281, QQ-N-286 Specifications A276/A479/ QQ-N-281, QQ-N-286
A479M, Types 302, 304,
316, 410, 430
Specification B21/B21M Specification B21/B21M
Specifications A276/A479/
A479M, Types 302, 304,
316, 410, 430
A A
Springs Specification A125 QQ-N-281, QQ-N-286 Specification A125 QQ-N-281, QQ-N-286
A A
Specification A227/A227M Specification A227/A227M
A A
Specification A229/A229M Specification A229/A229M
A A
Specification A231/A231M Specification A231/A231M
Specifications A276, A313/ Specifications A276, A313/
A313M A313M
A A
Specification A689 Specification A689
Body bolts and nuts Specifications A193/A193M, QQ-N-281, QQ-N-286 Specification A193/A193M QQ-N-281, QQ-N-286
A194/A194M, B164
Specifications F467, F468 Specification B164 Specification A194/A194M Specifications B164, F467,
F468
Diaphragm, gasket, and so TFE or reinforced TFE, nitrile TFE or reinforced TFE TFE or reinforced TFE, nitrile TFE or reinforced TFE, nitrile
forth (Buna-N), fluorocarbon- (Buna-N), fluorocarbon- (Buna-N), fluorocarbon-rubber
rubber (viton) rubber
Nonmetallic disk insert TFE or reinforced TFE TFE or reinforced TFE TFE or reinforced TFE TFE or reinforced TFE
Plastic in accordance with MIL- Plastic in accordance with MIL- Plastic in accordance with MIL- Plastic in accordance with MIL-
P-46122 P-46122 P-46122 P-46122
Plastic in accordance with Plastic in accordance with Plastic in accordance with Plastic in accordance with Clas-
Classification System D5204 Classification System D5204 Classification System D5204 sification System D5204
A
Electroless nickel plated (ENP).
TABLE 10 Pressure Temperature Ratings of Valve
End Connection
Code Type of End Connection Pressure-Temperature Rating (see 6.3.3)
(see Table 3)
A thru E ANSI Flanged Refer to ASME B16.5
F SBU, MIL-F-1183 (400 psi)
G Union-End, Drawing 803-1385946 (1500 psi) Nominal Design Design Shell Test
H Union-End, Drawing 803-1385943 (3000 psi) Pressure, Pressure, Temperature, Pressure,
I Union-End, Drawing 803-1385884 (6000 psi) psi psig °F psig
K 6-in. long nipple welded (400 psi)
L 6-in. long nipple welded (1500 psi) 400 480 165 800
M 6-in. long nipple welded (3000 psi) 1500 1800 165 2250
N 6-in. long nipple welded (6000 psi) 3000 3600 165 4500
6000 7200 165 9000
P, R, T Navy flanged, MIL-F-20042 Refer to MIL-F-20042
W As specified As specified
requiring pressure-tight (nonvented) bonnets, a stuffing box or 6.3.13 Gagging Device—When specified for system test
asealontheshaftofthehand-liftingdevicewhichwillhaveno purposes (see 6.2), a gagging device shall be supplied with the
effect on the valve set pressure and the valve lift, shall be valve. Valves shall be constructed to be gagged without
required. alteration of the set point.The gagging screw shall be provided
F1508−96 (2021)
TABLE 11 Nominal Tube Sizes (Inches) for Vented-Bonnet Valves
6.3.15.2 Valves shall have adjustable blowdown using
Valve Inlet Size Nominal Tube Size blowdown ring(s). Positive means shall be used to lock the
0.250 0.375 adjusting ring(s) in place by use of adjustable ring pins(s). The
0.375 0.375
pin(s) shall be installed through the penetration hole in the
0.500 0.375
lower valve body.
0.750 0.375
1.000 0.500 6.3.16 Valve Envelope Dimensions—Unless otherwise
1.250 0.500
specified in the ordering data, valves must meet the overall
1.500 0.625
envelope dimensions shown in Table 12 for Type I valves and
2.000 0.625
2.500 0.750 Table 13 for Types II and III valves.
3.000 0.750
6.3.17 Cleaning—Type II, Grade D valve parts (for oxygen
4.000 1.000
service) shall be cleaned in accordance with MIL-STD-1330
5.000 1.000
6.000 1.250
and maintained oxygen clean.
8.000 1.250
6.3.18 Sealing—Meansshallbeprovidedinthedesignofall
valves for sealing all external adjustments such as set pressure.
Seals shall be installed by the manufacturer or assembler at the
time of initial shipment and after field adjustment or repair of
with a knurled or wing nut-type head to discourage the use of
the valves by either the manufacturer, his authorized represen-
wrenches when gagging the valve.The gagging device shall be
tative repairer, or the user. Seals shall be installed in such a
constructed to minimize the possibility of overlooking its
mannerastopreventchangingtheadjustmentwithoutbreaking
removal after test and shall include a tag or other warning to
the seal and, in addition, shall serve as a means of identifying
this effect.The gagging device shall be designed to prevent the
the manufacturer, assembler, repairer, or user making the
installation of a valve cap over the gagging device.
adjustment.
6.3.14 Accessibility—Valves shall permit adjustment and
6.3.19 Asbestos material is not permitted in the valve
repair without removal from the line.
construction.
6.3.15 Valve Adjustment:
6.3.15.1 Means shall be provided for adjusting the set
7. Performance Requirements
pressure setting with the valve under pressure. The adjusting
7.1 All valves shall meet the requirements of 7.2 – 7.10.
screw shall have right-hand threads so that clockwise rotation
increases the set pressure. The adjusting device shall be 7.2 Range of Set Pressure Adjustment—ForType I andType
provided with a locknut and cap, or other suitable means, to
III valves, the set pressure shall be adjustable over a range of
prevent accidental change of adjustment. atleast 610 %ofthespecifiedsetpressure,forsetpressuresup
TABLE 12 Valve Envelope Dimensions (Inches) for Type I Valves (See Fig. 1)
NOTE 1—Variations for A and B dimensions are ±0.06 in. C is the maximum dimension shown.
NOTE 2—Dimensions not shown in the table shall be in accordance with API 526. If dimensions are not shown in Table 12, or are not listed in API
526, they should be agreed upon between the buyer and the valve supplier.
Type of Inlet × Outlet End Connections
Inlet Outlet ANSI 300 × ANSI 600 ×
Size Size ANSI 150 ANSI 150
AB C A B C A B C A B C A BCABCABCABC
0.25 0.25
0.25 0.50
0.50 0.50 3.2 3.2 3.2 3.5
0.50 1.00
0.75 0.75 3.2 3.2 3.2 3.5
1.00 1.00 3.5 3.5 3.4 3.7
1.00 2.00
1.25 1.25 3.7 3.7 3.7 4.0
1.50 1.50 4.7 4.7 4.7 5.0
1.50 2.00
1.50 2.50
2.00 2.00 4.7 4.7 4.7 5.0
2.00 3.00
2.50 2.50 5.5 5.5 5.5 5.7
3.00 3.00 6.4 6.0 6.4 6.2
3.00 4.00
3.50 3.50
4.00 4.00 7.0 7.0 7.0 7.2
4.00 5.00
4.00 6.00
5.00 5.00
6.00 8.00
8.00 10.0
F1508−96 (2021)
TABLE 13 Valve Envelope Dimensions (Inches) for Type II, Grade C, and Type III Valves (see Fig. 1) (Without Tailpieces and Nuts)
NOTE 1—Variations for A and B dimensions are ±0.06 in. C is the maximum dimension shown.
NOTE 2—Dimensions do not include length of nut or tailpiece.
NOTE 3—Dimensions not shown in the table should be agreed upon between the buyer and the valve supplier.
Type of Inlet and Outlet End Connections
Out- 803–1385946 803–1385943 803–1385884
Inlet MIL-F-1183 SBU- MIL-F-20042 MIL-F-20042 ANSI Class 150 ANSI Class 300
let Union Union Union
Size 400 PSI Flanged, 150# Flanged, 250# Flanged Flanged
Size 1500 PSI 3000 PSI 6000 PSI
AB C A B C A B C A B C A B C A B C A B C A B C
0.25 0.25 2.6 2.6 12.0 2.6 2.6 12.0 2.6 2.6 13.0 2.6 2.6 13.0 3.0 3.0 13.0 3.0 3.0 13.0 3.0 3.0 13.0
0.37 0.37 2.6 2.6 12.0 2.6 2.6 12.0 2.6 2.6 13.0 2.6 2.6 13.0 3.0 3.0 13.0 3.0 3.0 13.0 3.0 3.0 13.0
0.50 0.50 2.6 2.6 12.0 2.6 2.6 12.0 2.6 2.6 13.0 2.6 2.6 13.0 3.0 3.0 13.0 3.0 3.0 13.0 3.0 3.0 13.0
0.50 1.00 3.0 3.5 13.0 3.0 3.5 13.0 3.0 3.5 13.0
0.75 0.75 2.6 2.6 12.0 2.6 2.5 12.0 2.6 2.6 13.0 2.6 2.5 13.0 3.0 3.0 13.0 3.0 3.0 13.0 3.0 3.0 13.0
1.00 1.00 3.1 3.1 15.0 3.1 3.1 15.0 3.1 3.1 16.0 3.1 3.1 16.0 3.5 3.5 15.0 3.5 3.5 15.0 3.5 3.5 15.0
1.00 2.00
1.25 1.25 3.2 3.2 15.5 3.2 3.2 15.5 3.2 3.2 16.5 3.2 3.2 16.5 3.8 3.8 16.0 3.8 3.8 16.0 3.8 3.8 16.0
1.50 1.50 4.0 4.0 17.0 4.0 4.0 17.0 4.0 4.0 18.0 4.0 4.0 18.0 4.7 4.7 17.0 4.7 4.7 17.0 4.7 4.7 17.0
1.50 2.00 4.5 4.0 19.0 4.5 4.0 19.0 4.5 4.0 20.0 4.5 4.0 20.0 4.7 4.7 18.0 4.7 4.7 18.0 4.7 4.7 18.0
1.50 2.50 5.5 4.7 18.5 5.5 4.7 18.5 5.5 4.7 18.5
2.00 2.00 4.5 4.5 18.5 4.5 4.5 18.5 4.5 4.5 19.5 4.5 4.5 19.5 4.7 4.7 18.0 4.7 4.7 18.0 4.7 4.7 18.0
2.00 3.00
2.50 2.50 5.5 5.5 21.0 5.5 5.5 21.0 5.5 5.5 22.0 5.5 5.5 22.0 5.5 5.5 19.0 5.5 5.5 19.0 5.5 5.5 19.0
3.00 3.00 6.0 5.5 19.5 6.0 5.5 19.5 6.0 5.5 19.5
3.00 4.00
3.50 3.50 6.0 5.5 19.5 6.0 5.5 19.5 6.0 5.5 19.5
4.00 4.00 6.5 6.5 24.0 7.0 7.0 24.5 7.0 7.0 24.5
4.00 5.00
4.00 6.00 9.0 6.5 30.0 9.0 6.5 30.0 9.0 6.5 30.0
5.00 5.00 6.5 6.5 24.0 7.0 7.0 24.5 7.0 7.0 24.5
6.00 8.00 10.0 9.5 28.0 10.0 9.6 28.0 10.0 9.6 28.0
8.00 8.00 10.0 10.0 28.0 10.0 10.0 28.0 10.0 10.0 28.0
TABLE 14 Range of Set Pressure Adjustment for Type II Valves TABLE 15 Allowable Seat Leakage Rates
Nominal Pressure Minimum Required Set Maximum Required Set Maximum Allowable Seat
2 2 2
Rating, lb/in. gauge Pressure, lb/in. gauge Pressure, lb/in. gauge Valve Type Test Medium Type of Seat Leakage Over a Period of
Minimum 3 min
400 . . . 460
1500 460 1725 I steam metallic no visible evidence of
3000 1725 3450 steam leakage when
6000 3450 6875 the valve outlet is
viewed against a dark
background
II air or nitrogen nonmetallic no visible leakage as
gas indicated by a
to 250 psig; and when the specified set pressure exceeds 250
submerged underwater
or a soap bubble test
psig, this range shall be 65 %. For Type II valves, the set
III water nonmetallic no visible leakage
pressure shall be adjustable over the set pressure range
specified in Table 14. If required, more than one spring may be
used to accomplish this.
7.3 Operation—Valves shall operate without instability shall open with a clear, sharp pop. Valve closure shall be clear
throughout their full range of capacity. Types I and II valves and sharp when the inlet pressure is reduced to the blowdown
F1508−96 (2021)
A 2
TABLE 16 Effective Discharge Areas (A), in.
7.10 Effective Discharge Area (A)—Valves shall meet the
Valve (A) for Steam (A) for Air/Gas (A) for
effective discharge areas (A) specified in Table 16 based on
Inlet Size Valves Valves Liquid Valves
flow tests and neglecting any inlet/outlet losses (in accordance
0.250 0.018 0.016 0.011
with API RP 520, Part 1, Appendix C).
0.375 0.041 0.035 0.024
0.500 0.132 0.141 0.096
NOTE 1—To calculate the required effective discharge area for a given
0.750 0.162 0.141 0.096
relief capacity requirement, see the following examples for steam, gas,
1.000 0.285 0.249 0.160
1.250 0.444 0.389 0.280 and liquid services (for additional details, refer to API RP 520, Part 1,
1.500 0.638 0.559 0.432
Appendix C):
2.000 1.140 0.998 0.834
NOTE 2—The formulae shown in Examples 1, 2, and 3 are for valves
2.500 1.780 1.560 1.372
with vented/exposed spring construction bonnets. Nonvented bonnet
3.000 2.560 2.250 2.000
valves generally have much lower capacity and the valve manufacturer
4.000 4.550 3.990 3.727
should be consulted to obtain their capacities. Also, the calculated
A
Variation allowed on the discharge areas is +15 %, −0 %.
effective discharge area does not include impact as a result of installation
limitation in accordance with 7.9.
Example 1, Steam Service:
pressure. Type III valves shall open/close gradually, without
Given: Flow medium = saturated steam
instability,inresponsetotheincrease/decreaseinpressureover Upstream pressure = 100 psig
Accumulation = 10 %
the opening pressure.
Required flow through valve = 1774 lb/h
Calculate: A (effective discharge area of valve)
7.4 Hydrostatic Shell Test Pressure—The valve shall show
For steam service, use formula “C-10” in API RP 520,
no signs of external leakage, permanent deformation, or
Part 1, Appendix C
structural failure when subjected to the hydrostatic shell test
W
pressure specified in 8.2.
A 5 (1)
50P K
1 SH
7.5 Set Pressure Tolerance—For all types of valves, the set
where:
pressure tolerance, plus or minus, shall not exceed the follow-
A = effective discharge area of valve, in. ,
ing: 2 psi for set pressures up to 70 psig, 3 % for set pressures
W = required flow through valve, lb/h,
over 70 psig up to 300 psig, 10 psi for set pressures over 300
P = upstream relieving pressure, psia = 124.7 at 100-psig set
psig up to 1000 psig, and 2 % for set pressures over 1000 psig.
pressure, and
K = correction factor as a result of amount of superheat in steam =
SH
7.6 Accumulation—Valves shall be sized to pass the speci-
1.0 for saturated steam.
fied flow (see 5.1.6) without permitting the inlet pressure
Then substituting these values in Eq 1,
(source static pressure) to rise beyond the accumulation pres-
sure. The accumulation (overpressure) shall not exceed 10 %
A 5 5 0.285 in. (2)
of set pressure, or 3 psi, whichever is greater. The valve shall
50 3124.7 31.0
show no signs of instability.
Example 2, Air Service:
Given: Flow medium = air
7.7 Blowdown Limits—Unless otherwise specified in the
Upstream pressure = 100 psig
ordering data (see 5.1.8), valves shall operate satisfactorily
Accumulation = 10 %
with the following blowdown pressure setting: Temperature = 60°F
Required flow through valve = 556 SCFM
7.7.1 For Type I and Type II valves, the maximum blow-
Calculate: A (effective discharge area of valve)
down limit shall be 3 psi or 7 % of the set pressure, whichever
For air service, use formula “C-3” in API RP 520, Part
1, Appendix C
is greater.
7.7.2 For Type III valves, the maximum blowdown limit
=
V TZG
shall not exceed 15 % of the set pressure or 3 psi, whichever is
A 5 (3)
1.175 CKP K
1 b
greater.
where:
7.8 Seat Tightness—With an inlet pressure at or above the
A = effective discharge area of valve, in. ,
minimumallowableblowdownpressuresetting,thevalveshall
C = coefficient determined by ratio of specific heats, for air C = 356,
seat tightly. No through seat leakage under this condition shall
K = effective coefficient of discharge = 0.975 for formula “C-3,”
be allowed (see Table 15).
V = required flow through valve, standard cubic feet per min at 14.7
psia and 60°F,
7.9 Installation Limitation—Valve operation shall not be
P = upstreamrelievingpressure,psia=124.7at100-psigsetpressure,
adversely affected (loss of capacity or instability) by an inlet
K = correction factor as a result of back pressure = 1.0 from “Figure
b
piping pressure loss of up to 25 % of the relief valve maximum
C-1,”
permitted blowdown or an outlet piping breakpressure buildup T = absolute temperature of the inlet air, °F + 460 = 520°F for given
data,
of up to 10 % of the set pressure, or both. Where the
Z = compressibility factor, assume Z = 1.0 for air, and
installation will subject the valve to more severe piping
G = specific gravity of gas referred to air = 1.0 for rated data.
restrictions, this information shall be noted in the ordering data
Then substituting these values in the formula,
(see 5.1.7).
F1508−96 (2021)
FIG. 1Typical End Connections
8. Tests Required
556=520 31.0 31.0
A 5 5 0.249 in. (4)
1.175 3356 30.975 3124.7 31.0
8.1 Eachproductionvalvemustpassthetestsoutlinedin8.2
Example 3, Liquid Service: and 8.3.
Given: Flow medium = water
Upstream pressure = 100 psig 8.2 Hydrostatic Shell Test—Valve shall be gagged shut or
Accumulation = 10 %
disk and spring assembly removed and seat blanked off. The
Required flow through valve = 25.2 gpm
followingtwoseparatehydrostaticshelltestsforaminimumof
Calculate: A (effective discharge area of valve)
For liquid (water), use formula “C-7” in API RP 520, 3 min shall be performed: (a) Water or air/nitrogen at a test
Part 1, Appendix C
pressure (see Table 10) shall be applied to the valve inlet
(primary pressure zone) to verify conformance to 7.4.(b) For
gpm=G
A 5 (5)
valves with pressure-tight bonnet construction only, water or
38.0KK K K =1.25 P 2 P
p w v b
air/nitrogen at a test pressure specified in 6.3.3.2 shall be
where: applied to the valve outlet (secondary pressure zone) to verify
conformance to 7.4.
A = effective discharge area of valve, in. ,
gpm = flow rate required through the valve, gal/min,
8.3 Set Pressure, Blowdown, and Seat Tightness Test—Inlet
G = specific gravity of the liquid at flowing temperature = 1.0 for
pressure (see Table 15 for test medium) shall be increased until
water at rated conditions,
K = coefficient of discharge = 0.62,
the valve opens. Inlet pressure shall be reduced until the valve
K = capacity correction factor because of 10 % overpressure = 0.6
p reseats. Leakage shall be checked over a 3-min period at an
at 10 % accumulation, see “Figure C-4,”
inlet pressure equal to the minimum allowable blowdown
K = capacity for correction factor as a result of back pressure = 1.0,
w
pressure setting. There shall be no damage to seating surfaces
see “Figure C-5,”
and no instability (chatter). The valve shall conform to the
K = capacity correction factor as a result of viscosity = 1.0, see
v
“Figure C-6,” requirements in accordance with 7.5, 7.7, and 7.8.
P = set pressure, psig = 100, and
P = back pressure, psig = 0.0 for given data.
b
9. Marking
Then substituting these values in the formula,
9.1 Each valve shall be plainly and permanently marked by
25.2 3=1.0 the manufacturer with the required data in such a way that the
A 5 (6)
markingwillnotbeobliteratedinservice.Themarkingmaybe
38.0 30.62 30.6 31.0 31.0 3=1.25 3100 2 0.0
placed on the valve or on a corrosion-resistant plate perma-
50.160 in. nently attached to the valve. The following data is required:
F1508−96 (2021)
9.1.1 Name of the manufacturer, 9.2 All connections (inlet, outlet, drain, and so forth) shall
9.1.2 Manufacturer’s design or type number, be permanently marked to aid in correct installation of the
9.1.3 Valve specification code, pressure relief valve.
9.1.4 Size _____in. (nominal pipe size of the valve inlet),
9.1.5 Set pressure _____psi, 10. Quality Assurance System
9.1.6 Rated relieving capacity (as applicable):
10.1 Themanufacturershallestablishandmaintainaquality
assurancesystemwhichwillensurethatalltherequirementsof
NOTE 3—The information listed in 9.1.5 and 9.1.6 must be placed on a
corrosion-resistant plate permanently attached to the valve. this specification are satisfied. This system shall also ensure
that all valves will perform in a similar manner to those
9.1.6.1 Pounds per hour of saturated steam at an overpres-
representative valves subjected to original testing for determi-
sure of 10 % of set pressure or 3 psi, whichever is greater, for
nation of the operating and flow characteristics.
valves used in steam service; or
9.1.6.2 Gallon per minute of water at 70°F at an overpres-
10.2 A written description of the system the manufacturer
sure of 10 % of set pressure or 3 psi, whichever is greater, for
will use shall be available for review and acceptance by the
valves used in water service; or
purchaser or his designee.
9.1.6.3 SCFM (standard cubic feet per minute at 60°F and
NOTE 4—If Supplementary Requirement S4 is specified in 5.1.10,an
14.7 psia) of air at an overpressure of 10 % of set pressure or
outline of subjects described in S4 shall be provided by the manufacturer.
3psi,whicheverisgreater,forvalvesusedinairorgasservice.
10.3 The purchaser or his designee reserves the right to
9.1.6.4 ForTypeIvalves(wheretheoutletsizeislargerthan
witness the production tests and inspect the valves in the
the inlet size), the effective orifice area letter designation in
manufacturer’s plant to the extent specified on the purchase
accorda
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