ASME Specification for Fastener Materials (Article-5)
In the article about Property Class as per ASME (The American Society of Mechanical Engineers) we have seen that there are many ASME specifications for making threaded fasteners. In this article information is given about their scope. Grades
of material available in each specification are also listed. Specifications contain information on ordering, manufacturing process, heat treatment, chemical composition, mechanical requirements, etc. Information is also given on supplementary requirement to be specified in purchase order. For detail information, please refer the specifications. Note:
This article is theoretical in nature and is given to maintain sequence of articles on threaded fasteners. You may skip reading this article or read underlined key words.
Bolting material – Rolled or forged bars or blanks, wire, rod, threaded bar, rotary pierced or extruded seamless tubes, bored bars, or forged hollows from forged or rolled bar segments to be manufactured into bolts, screws, studs, washers, and nuts.
Grade – An alloy described individually and identified by its own designation in a table of chemical requirements within any specification.
Class – A term used to differentiate between different heat treatment conditions or strength levels, or both, often within the same Grade but sometimes within the same family of materials. May also apply to work hardened condition or strength level, or both.
ASME Specification SA–962 / SA–962M
SA 962 / SA 962M is – Specification for common requirements for steel fasteners or fastener materials, or both, intended
for use at any temperature from cryogenic to the creep range. Its scope covers a group of common requirements that shall apply to carbon, alloy and stainless steel fasteners or fastener materials, or both under any of the following ASTM (The American Society for Testing and Materials) specification numbers.
A 193 / A 193M
A 194 / A 194M
A 320 / A 320M
A 437 / A 437M
A 453 / A 453M and
A 540 / A 540M
As per the supplementary requirements, bolts, studs and bolting material for dynamic service shall be examined for decarburization and surface discontinuities as under.
The surface discontinuities shall conform to specification ASTM F 788 / 788M.
Thread lap inspection shall be performed in accordance with ASTM F 788 / 788M. Threads shall have no laps at the root, or on the flanks initiating or extending below the pitch line.
Quench cracks of any depth, any length, or in any location are not permitted.
Folds at the junction of the head and the shank are not permitted.
A stress relieving operation shall follow straightening or cold drawing (for dimensional control) after heat treatment.
When ASTM material is shown under ASME number, S is added in front of ASTM number. For example, specification A 193 of
ASTM is called SA-193 under ASME.
ASME Specification SA–193 / SA–193M
ASME SA 193 / SA 193M is - Specification for alloy-steel and stainless steel bolting material for high-temperature service.
Its scope covers alloy and stainless steel bolting material for pressure vessels, valves, flanges and fittings for
In the specification, many grades of ferritic and austenitic steel are given as under. Selection of a grade will depend
upon design, service conditions, mechanical properties and high-temperature characteristics.
Type Grade Description
Ferritic Steel B5 5 % Chromium
Ferritic Steel B6, B6X 12 % Chromium, AISI Type 410
Ferritic Steel B7, B7M Chromium-Molybdenum
Ferritic Steel B16 Chromium-Molybdenum-Vanadium
Austenitic Steel B8, B8A AISI Type 304
Austenitic Steel B8C, B8CA AISI Type 347
Austenitic Steel B8M, B8MA, B8M2, B8M3 AISI Type 316
Austenitic Steel B8P, B8PA AISI Type 305 with restricted Carbon
Austenitic Steel B8N, B8NA AISI Type 304N
Austenitic Steel B8MN, B8MNA AISI Type 316N
Austenitic Steel B8MLCuN, B8MLCuNA Unstabilized, 20 Chromium, 18 Nickel, 6
Molybdenum with restricted Carbon Austenitic Steel B8T, B8TA AISI Type 321
Austenitic Steel B8R, B8RA 22 Chromium-13 Nickel-5 Manganese Austenitic Steel B8S, B8SA 28 Chromium-8 Nickel-4 Silicon + Nitrogen Austenitic Steel B8LN, B8LNA AISI Type 304N with restricted Carbon Austenitic Steel B8MLN, B8MLNA AISI Type 316N with restricted Carbon For a grade of material, there are many classes depending on heat treatment. For example, Grade B8 has three classes,
Class 1, Class 2 and Class 2B.
Austenitic stainless steel may be carbide solution treated or carbide solution treated and strain hardened.
Chemical composition of some grades is as under ASTM A-193/ASME SA-193
Grade B5 B6 B7/B7M B16 B8 B8M C 0.10 min 0.15 max 0.37-0.49 0.36 -0.47 0.08 max 0.08 max Mn 1.00 max 1.00 max 0.65-1.10 0.65 -1.10 2.00 max 2.00 max P, max 0.040 0.040 0.035 0.035 0.045 0.045 S, max 0.030 0.030 0.040 0.04 0.030 0.030 Si 1.00 max 1.00 max 0.15-0.35 0.15 -0.35 1.00 max 1.00 max Ni - - - - 8.00-10.50 10.00-14.00 Cr 4.00-6.00 11.50 -13.50 0.75 -1.20 0.80 -1.15 18.00 -20.00 16.00 -18.00 Mo 0.40-0.65 - 0.15-0.25 0.50 -0.65 - 2.00-3.00 V - - - 0.25-0.35 - -
Al, max - - - 0.015 - -
For grades of alloy-steel bolting material suitable for use at lower range of high-temperature applications, reference should be made to ASME Specification SA 354.
ASME Specification SA–194 / SA–194M
ASME SA 194 / SA 194M is - Specification for carbon and alloy steel nuts for bolts for high-pressure or high-temperature
service, or both. Its scope covers a variety of carbon, alloy and martensitic stainless steel nuts in the size range M6
through M100 nominal. It also covers austenitic stainless steel nuts in the size range M6 nominal and above.
Nuts are made in many grades as under to suit variety of bolting material.
Grade Symbol Material
2, 2HM and 2H Carbon
4 Carbon, molybdenum
3 AISI 501
6 AISI 410
6F AISI 416 with sulfur
6F AISI 416 with selenium
7, 7M AISI 4140 / AISI 4142 / AISI 4145 / 4140H, 4142H, 4145H
8, 8A AISI 304
8C, 8CA AISI 347
8M, 8MA AISI 316
8T, 8TA AISI 321
8F, 8FA AISI 303 with sulfur
8F, 8FA AISI 303 with selenium
8P, 8PA AISI 305 with restricted carbon 8N, 8NA AISI 304N
8LN, 8LNA AISI 304N with restricted carbon 8MN, 8MNA AISI 316N
8MLN, 8MLNA AISI 316N with restricted carbon 8R, 8RA XM19
8S, 8SA -
8MLCuN, 8MLCuNA S31254
9C, 9CA N08367
16 Chromium Molybdenum vanadium
Chemical composition of some grades is as under
ASTM A-194/ASME SA-194
Grade 2H/2HM 3 4 6 7/7M 8 8M C 0.40 min 0.10 min 0.40-0.50 0.15 max 0.37-0.49 0.08 max 0.08 max Mn 1.00 max 1.00 max 0.70-0.90 1.00 max 0.65-1.10 2.00 max 2.00 max P, max 0.040 0.040 0.035 0.040 0.040 0.045 0.045 S, max 0.050 0.030 0.040 0.030 0.040 0.030 0.030 Si 0.40 max 1.00 max 0.15-0.35 1.00 max 0.15-0.35 1.00 max 1.00 max
Ni - - - - - 8.00-10.50 10.00-14.00
Cr - 4.00-6.00 - 11.50-13.50 0.75 -1.20 18.00-20.00 16.00 -18.00
Mo - 0.40-0.65 0.20 -0.30 - 0.15-0.25 - 2.00-3.00
When strain hardening is required with strain hardened Grades 8, 8C, 8T, 8M, 8F, 8P, 8N or 8MN, it shall be specified in the order. For this, nuts shall be machined from cold drawn bars or shall be cold forged to shape. No subsequent heat treatment shall be performed on the nuts.
Coatings on nuts are prohibited unless specified by the purchaser. Use of coated fasteners at temperature above approximately one-half the melting point of coating is not recommended unless consideration is given to the potential for liquid and solid metal embrittlement, or both. The melting point of elemental zinc is approximately 415 ºC. Therefore,
application of zinc coated fasteners should be limited to temperature less than 210ºC.
ASME Specification SA–307
ASME SA 307 is - Specification for carbon steel bolts and studs, 60000 PSI tensile strength. Its scope covers the chemical
and mechanical requirements of three grades of carbon steel bolts and studs in sizes ? inch through 4 inch. The fasteners are designated by “Grade” denoting tensile strength and intended use as follows.
Bolts and studs having a minimum tensile strength of 60 ksi (414 MPa) and intended for Grade A general applications.
Bolts and studs having a tensile strength of 60 to 100 ksi (414 to 690 MPa) and intended Grade B for flanged joints in piping system with cast iron flanges.
Nonheaded anchor bolts (studs), either bent or straight, having properties conforming Grade C to Specification A 36 (tensile strength of 58 to 80 ksi – 400 to 550 MPa) and intended
for structural anchorage purposes.
Suitable nuts are covered in specification SA 563. Unless otherwise specified, the grades shall be as follows.
Fastener Grade and Size Nut Grade and Style
A, C, ? to 1 ? inch A, hex
A, C, over 1 ? to 4 inch A, heavy hex
B, ? to 4 inch A, heavy hex
Supplementary requirement shall be included in the purchase order if bolts are to be welded. ASME Specification SA–320 / SA-320M
SA 320 / SA 320M is - Specification for alloy steel bolting material for low-temperature service. Its scope covers alloy steel bolting materials for pressure vessels, valves, flanges and fittings for low-temperature service. Its scope covers
several grades, including both ferritic and austenitic steels as under.
Type Identification Symbol Grade
Ferritic Steels L7, L7M, L70 Chromium-Molybdenum (AISI 4140,4142, or 4145)
Ferritic Steels L7A, L71 Carbon-Molybdenum (AISI 4037)
Ferritic Steels L7B, L72 Chromium-Molybdenum (AISI 4137)
Ferritic Steels L7C, L73 Nickle-Chromium-Molybdenum (AISI 8740)
Ferritic Steels L43 Nickle-Chromium-Molybdenum (AISI 4340)
Ferritic Steels L1 Low-Carbon Boron
Austenitic Steels B8, B8A Unstabilized 18 Chromium-8 Nickel (AISI Type 304)
Austenitic Steels B8C, B8CA Stabilized 18 Chromium-8 Nickel (AISI Type 347)
Austenitic Steels B8T, B8TA Stabilized 18 Chromium-8 Nickel (AISI Type 321)
Unstabilized 18 Chromium-8 Nickel (AISI Type 305 with Austenitic Steels B8P, B8PA restricted carbon)
Austenitic Steels B8F, B8FA With added sulfur (Type 303)
Austenitic Steels B8F, B8FA With added selenium (Type 303 Se)
Austenitic Steels B8M, B8MA 18 Chromium-10 Nickel-2 Molybdenum (AISI Type 316)
Unstabilized 18 Chromium-8 Nickel with Nitrogen (AISI Type Austenitic Steels B8LN, B8LNA 304N with restricted carbon)
Unstabilized 18 Chromium-10 Nickel-2 Molybdenum with Austenitic Steels B8MLN, B8MLNA Nitrogen (AISI Type 316N with restricted carbon)
The standard stipulates the requirements for Charpy impact energy absorption.
Nuts for use with this bolting material are covered in Section 9 of the standard and require that the nut material shall be impact tested.
Washers for use with ferritic steel bolting shall conform to Specification F 436 and with austenitic steel shall be made of austenitic steel.
ASME Specification SA–325
SA 325 is - Specification for structural bolts, steel, heat treated, 120 / 105 ksi minimum tensile strength. Its scope covers two types of quenched and tempered steel structural bolts having a minimum tensile strength of 120 ksi for sizes 1.0 inch and less and 105 ksi for sizes over 1.0 to 1 ? inch inclusive.
The bolts are intended for use in structural connections. These connections are covered under the requirements of the Specifications for Structural Joints Using ASTM A 325 or A 490 Bolts, approved by the Research Council on Structural
Connections of the Engineering Foundation.
The bolts are designated by Type denoting chemical composition as follows.
Type 1 Medium carbon, carbon boron, or medium carbon alloy steel.
Type 2 Withdrawn in November 1991.
Type 3 Weathering steel.
Bolts for general application, including anchor bolts, are covered by Specification A 449. Also refer to Specification A 449 for quenched and tempered steel bolts and studs with diameters greater than 1 ? inch but with similar mechanical
Unless otherwise specified, all nuts used on these bolts shall conform to the requirements of Specification A 194 / A 194M or A 563, shall be heavy hex, as follows.
Bolt Type and Finish Nut Class and Finish
Type 1, Plain (uncoated) A 563 – C, C3, D, DH, DH3, plain A 194 – 2, 2H, plain
Type 1, zinc-coated A 563 – DH, zinc coated A 194 – 2, 2H, zinc coated
Type 3, plain A 563 – C3, DH3, plain
Unless otherwise specified, all washers used on these bolts shall conform to the requirements of Specification F 43 or F 959.