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Fastener & steel specifications

The ASTM callouts we use most on Bolt Brokers quotes — bolting, nuts, washers, and A36 structural steel. Grades, strengths, and typical mating hardware so you can brief a take-off or confirm the drawing.

Bolts Nuts Washers Steel Torque chart Isolation kits Request a quote

Educational summaries — not a substitute for the ASTM standard

Values below are common published reference figures for RFQ briefing. Always quote and fabricate to the current edition named on the drawing or purchase order. Linked “technical summary” pages are free manufacturer references (Portland Bolt), not the copyrighted ASTM PDF.

Bolt specifications

Primary bolting callouts we quote most often — high-temp alloy, general carbon, and general-purpose stainless.

A193 A307 F593

ASTM A193 Alloy & stainless bolting (incl. Grade B7)

High-temperature / high-pressure bolting for flanges, valves, vessels, and fittings. Grade B7 (4140/4142 Q&T) is the everyday workhorse; B8/B8M cover 304/316 stainless.

Common grades

Grade Material / condition
B7 Alloy steel (AISI 4140/4142), quenched & tempered — most common for flanges & pressure service
B8 Class 1 Stainless 304, carbide solution treated
B8M Class 1 Stainless 316, carbide solution treated
B8 / B8M Class 2 Same alloys, strain hardened for higher strength

B7 mechanical properties (most used)

Size Tensile min, ksi Yield min, ksi Elong. min % RA min % Hardness max
Up to 2½″ 125 105 16 50 35 HRC / 321 HBW
2⅝″ – 4″ 115 95 16 50 35 HRC / 321 HBW
4⅛″ – 7″ 100 75 18 50 35 HRC / 321 HBW

Typical mating hardware

Bolt Nuts Washers
B7 A194 Grade 2H F436
B8 Class 1 A194 Grade 8 304 stainless
B8M Class 1 A194 Grade 8M 316 stainless

Above 1″ diameter, traditional A193 practice often uses 8 TPI unless UNC is specified. Pair B7 with the bolt torque chart for starting values only.

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

ASTM A307 Carbon steel bolts & studs

General-purpose carbon steel bolts and threaded rod, ¼″ through 4″. Grade A for everyday work; Grade B for cast-iron flange joints.

Grades

Grade Typical product / use
A Headed bolts, threaded rod, bent bolts — general applications
B Heavy hex bolts & studs — flanged joints with cast-iron flanges
C (legacy) Replaced by F1554 Grade 36 for anchor bolts (Aug 2007)

Mechanical properties

Grade Tensile, ksi Yield min, ksi Elong. min %
A 60 min — 18
B 60 – 100 — 18
C (legacy) 58 – 80 36 23

Typical mating hardware

Bolt Nuts Washers
A307 A (≤1½″) A563 Grade A hex F844 (general) or as specified
A307 A (>1½″) A563 Grade A heavy hex As specified
A307 B A563 Grade A heavy hex As specified

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

ASTM F593 Stainless bolts, screws & studs

General-purpose stainless fasteners, ¼″–1½″, in seven alloy groups (304 and 316 families are Groups 1 and 2).

Alloy groups (common)

Group Typical alloys Type
1 303, 304, 304L, 305, 302HQ… Austenitic
2 316, 316L Austenitic
3 321, 347 Austenitic
5 / 6 / 7 410, 431, 630 (17-4) Martensitic / PH

Mechanical — Groups 1 & 2 (304 / 316 family)

Group Condition Mark Diameter Tensile, ksi Yield min, ksi
1 AF F593A ¼–1½″ 65–85 20
1 A F593B ¼–1½″ 75–100 30
1 CW1 F593C ¼–⅝″ 100–150 65
1 CW2 F593D ¾–1½″ 85–140 45
2 AF F593E ¼–1½″ 65–85 20
2 A F593F ¼–1½″ 75–100 30
2 CW1 F593G ¼–⅝″ 100–150 65
2 CW2 F593H ¾–1½″ 85–140 45

Typical mating hardware

Bolts Nuts Washers
F593 F594 (same alloy group) 304 or 316 stainless (match bolt)

General-purpose stainless. For high-temp / high-pressure service, A193 B8/B8M is usually the better callout.

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

Nut specifications

Match nut grade to the bolt — A194 with A193, A563 with A307 / structural, F594 with F593.

A194 A563 F594

ASTM A194 High-pressure / high-temperature nuts

Carbon, alloy, and stainless heavy hex nuts for pressure and temperature service. Grade 2H is the standard mate for A193 B7.

Common grades

Grade Material
2 Carbon steel heavy hex
2H Quenched & tempered carbon steel heavy hex — most common with B7
2HM Q&T carbon steel, 100% hardness tested
7 / 7M Q&T alloy steel (7M = 100% hardness tested)
8 / 8M Stainless 304 / 316

Proof load & hardness (heavy hex, coarse / 8UN)

Grade Size Proof load, ksi Hardness
2 ¼–4″ 150 159–352 HB
2H ¼–4″ 175 C24–C38
2HM ¼–4″ 150 159–237 HB
7 ¼–4″ 175 C24–C38
8 / 8M ¼–4″ 80 126–300 HB

Default geometry is heavy hex (ANSI/ASME B18.2.2). A194 2H is often substituted for A563 DH when DH is hard to source in larger sizes.

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

ASTM A563 Carbon & alloy steel nuts

General structural and mechanical nuts. Grade A with A307; DH (or A194 2H substitute) for high-strength bolting.

Common grades

Grade Notes
A Carbon steel hex or heavy hex — general use with A307
B Carbon steel heavy hex
C / D Higher strength carbon, heavy hex
DH Quenched & tempered carbon, heavy hex — high-strength structural
C3 / DH3 Weathering steel versions

Proof load (UNC / 8UN / coarse)

Grade Style Size Proof plain, ksi Proof galv, ksi
A Hex ¼–1½″ 90 68
A Heavy hex ¼–4″ 100 75
B Heavy hex ¼–1″ 133 100
C / C3 Heavy hex ¼–4″ 144 144
D Heavy hex ¼–4″ 150 150
DH / DH3 Heavy hex ¼–4″ 175 150

Hot-dip galvanized nuts are tapped oversize to clear zinc on the bolt threads. Stronger A563 grades may be substituted for weaker ones unless the PO forbids it.

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

ASTM F594 Stainless nuts

Stainless nuts for F593 bolts — same alloy groups. Specify the group (and alloy if required) to match the bolt.

Alloy groups

Same seven alloy groups as F593. Match the nut group (and preferably alloy) to the F593 bolt.

Proof stress — Groups 1 & 2

Group Condition Mark Diameter Proof hex, ksi Proof heavy hex, ksi
1 AF F594A ¼–1½″ 70 76
1 A F594B ¼–1½″ 75 81
1 CW1 F594C ¼–⅝″ 100 108
1 CW2 F594D ¾–1½″ 85 92
2 AF F594E ¼–1½″ 70 76
2 A F594F ¼–1½″ 75 81
2 CW1 F594G ¼–⅝″ 100 108
2 CW2 F594H ¾–1½″ 85 92

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

Washer specifications

Hardened structural washers vs. general-purpose flat washers.

F436 F844

ASTM F436 Hardened steel washers

Heat-treated washers for structural and high-strength bolting. Use with F3125 / A325 / A490, A193, and similar callouts.

Types & styles

Description
Type 1 Carbon steel
Type 3 Weathering steel
Circular Round SAE pattern, ¼″–4″
Beveled ~2:12 slope for American Standard beams, ½″–1½″
Clipped Circular or beveled where space is tight

Hardness

Finish Rockwell hardness
Plain 38–45 HRC
Hot-dip galvanized 26–45 HRC

Hardened washers for structural and high-strength bolting — A325/A490 (F3125), A193, A354, F1554, and whenever the drawing calls for hardened washers.

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

ASTM F844 Unhardened flat washers

General-purpose flat washers — larger OD than F436, no mechanical requirements unless added on the PO. Common with A307.

What it covers

Unhardened flat washers (round and miscellaneous shapes), typically with a larger OD than F436. General-purpose — common with A307 and light duty assemblies.

Topic Requirement
Mechanical None, unless the PO adds them
Chemical Steel; no composition limits unless specified
Dimensions Usually ASME B18.21.1 standard flat washers
Coatings Plain or hot-dip galvanized

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

Steel specification

Structural carbon steel that shows up on many RFQs alongside fastener packages.

A36

ASTM A36 Carbon structural steel

Shapes, plates, and bars for bridges, buildings, and general structural work. 36 ksi minimum yield.

Mechanical (bars — abbreviated)

Property Requirement
Tensile 58–80 ksi
Yield, min 36 ksi
Elongation min in 2″ 20%
Elongation min in 8″ 23%

Chemistry (bars — abbreviated)

Thickness C max Mn P max S max
Up to ¾″ 0.26% — 0.04% 0.05%
Over ¾″ to 1½″ 0.27% 0.60–0.90% 0.04% 0.05%
Over 1½″ to 4″ 0.28% 0.60–0.90% 0.04% 0.05%
Over 4″ 0.29% 0.60–0.90% 0.04% 0.05%

Shapes, plates, and bars for bridges, buildings, and general construction. Fasteners made from A36-type steel often ship as A307 or F1554 Grade 36 rather than “A36 bolts.”

Technical summary (Portland Bolt) · Summaries for RFQ briefing — always fabricate to the current ASTM edition on the PO.

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