ASTM A320/A320M-07
(Specification)Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service
Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service
SCOPE
1.1 This specification covers alloy steel bolting materials for pressure vessels, valves, flanges, and fittings for low-temperature service. The term "bolting material" as used in this specification covers rolled, forged, or strain hardened bars, bolts, screws, studs, and stud bolts. The bars shall be hot-wrought. The material may be further processed by centerless grinding or by cold drawing. Austenitic stainless steel may be solution annealed or annealed and strain-hardened. When strain hardened austenitic stainless steel is ordered, the purchaser should take special care to ensure that Appendix X1 is thoroughly understood.
1.2 Several grades are covered, including both ferritic and austenitic steels designated L7, B8, etc. Selection will depend on design, service conditions, mechanical properties, and low-temperature characteristics. The mechanical requirements of Table 1 indicate the diameters for which the minimum mechanical properties apply to the various grades and Table 2 classes, and stipulates the requirements for Charpy impact energy absorption. The manufacturer should determine that the material can conform to these requirements before parts are manufactured. For example, when Grade L43 is specified to meet the impact energy values at 150°F [101°C], additional restrictions (such as procuring a steel with lower P and S contents than might normally be supplied) in the chemical composition for AISI 4340 are likely to be required.
Note 1—The committee formulating this specification has included several grades of material that have been rather extensively used for the present purpose. Other compositions will be considered for inclusion by the committee from time to time as the need becomes apparent. Users should note that hardenability of some of the grades mentioned may restrict the maximum size at which the required mechanical properties are obtainable.
1.3 Nuts for use with this bolting material are covered in Section 10 and the nut material shall be impact tested.
1.4 Supplementary Requirements (S1, S2, and S3) of an optional nature are provided. They shall apply only when specified in the inquiry, contract and order.
1.5 This specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable "M" specification designation (SI units), the material shall be furnished to inch-pound units.
1.6 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.
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Designation: A 320/A 320M – 07
Standard Specification for
Alloy-Steel and Stainless Steel Bolting Materials for Low-
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Temperature Service
ThisstandardisissuedunderthefixeddesignationA320/A320M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
restrictthemaximumsizeatwhichtherequiredmechanicalpropertiesare
1. Scope*
obtainable.
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1.1 This specification covers alloy steel bolting materials
1.3 Nuts for use with this bolting material are covered in
for pressure vessels, valves, flanges, and fittings for low-
Section 10 and the nut material shall be impact tested.
temperatureservice.Theterm“boltingmaterial”asusedinthis
1.4 Supplementary Requirements (S1, S2, and S3) of an
specification covers rolled, forged, or strain hardened bars,
optional nature are provided. They shall apply only when
bolts, screws, studs, and stud bolts. The bars shall be hot-
specified in the inquiry, contract and order.
wrought. The material may be further processed by centerless
1.5 This specification is expressed in both inch-pound units
grinding or by cold drawing.Austenitic stainless steel may be
and in SI units. However, unless the order specifies the
solution annealed or annealed and strain-hardened. When
applicable “M” specification designation (SI units), the mate-
strain hardened austenitic stainless steel is ordered, the pur-
rial shall be furnished to inch-pound units.
chaser should take special care to ensure that Appendix X1 is
1.6 The values stated in either inch-pound units or SI units
thoroughly understood.
are to be regarded separately as standard. Within the text, the
1.2 Several grades are covered, including both ferritic and
SI units are shown in brackets. The values stated in each
austenitic steels designated L7, B8, etc. Selection will depend
system are not exact equivalents; therefore, each system must
on design, service conditions, mechanical properties, and
beusedindependentlyoftheother.Combiningvaluesfromthe
low-temperature characteristics. The mechanical requirements
two systems may result in nonconformance with the specifi-
of Table 1 indicate the diameters for which the minimum
cation.
mechanical properties apply to the various grades and classes,
and Table 2 stipulates the requirements for Charpy impact
2. Referenced Documents
energyabsorption.Themanufacturershoulddeterminethatthe
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2.1 ASTM Standards:
material can conform to these requirements before parts are
A194/A194M Specification for Carbon and Alloy Steel
manufactured. For example, when Grade L43 is specified to
Nuts for Bolts for High Pressure or High Temperature
meet the Table 2 impact energy values at −150 °F [−101 °C],
Service, or Both
additional restrictions (such as procuring a steel with lower P
A370 TestMethodsandDefinitionsforMechanicalTesting
and S contents than might normally be supplied) in the
of Steel Products
chemical composition forAISI 4340 are likely to be required.
A962/A962M Specification for Common Requirements
NOTE 1—The committee formulating this specification has included
forSteelFastenersorFastenerMaterials,orBoth,Intended
several grades of material that have been rather extensively used for the
for Use at Any Temperature from Cryogenic to the Creep
present purpose. Other compositions will be considered for inclusion by
Range
the committee from time to time as the need becomes apparent. Users
E566 Practice for Electromagnetic (Eddy-Current) Sorting
should note that hardenability of some of the grades mentioned may
of Ferrous Metals
F436 Specification for Hardened Steel Washers
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This specification is under the jurisdiction ofASTM CommitteeA01 on Steel,
Stainless Steel and RelatedAlloys and is the direct responsibility of Subcommittee
A01.22onSteelForgingsandWroughtFittingsforPipingApplicationsandBolting
Materials for Piping and Special Purpose Applications.
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Current edition approved March 1, 2007. Published April 2007. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 1948. Last previous edition approved in 2005 as A320/A320M-05a. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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For ASME Boiler and Pressure Vessel Code applications, see related Specifi- Standards volume information, refer to the standard’s Document Summary page on
cation SA-320 in Section II of that Code. the ASTM website.
*ASummary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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