ASTM A194 High-Temperature Nuts
A194 is the nut specification that pairs with A193 and A320 studs. Grade 2H is the most common: a heavy hex carbon-steel nut for B7 studs.
Common grades and pairing
| Nut grade | Material | Pairs with |
|---|---|---|
| 2H | Carbon steel, Q&T | A193 B7 |
| 2HM | Carbon steel, hardness-controlled | A193 B7M (sour service) |
| 4 / 7 | Alloy steel | A320 L7 (impact-tested as specified) |
| 8 | 304 stainless | A193 B8 |
| 8M | 316 stainless | A193 B8M |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
ASTM A194 / A194M · nuts for high-temperature and pressure bolting
FIELD IDENTIFICATION
2H
What it is
A194 is the nut specification that pairs with A193 and A320 studs. Grade 2H is the most common: a
heavy hex carbon-steel nut for B7 studs.
Heavy hex nut, grade on face (2H shown)
Common grades and pairing
Nut grade
Material
Pairs with
2H
Carbon steel, Q&T
A193 B7
2HM
Carbon steel, hardness-controlled
A193 B7M (sour service)
4/7
Alloy steel
A320 L7 (impact-tested as specified)
8
304 stainless
A193 B8
8M
316 stainless
A193 B8M
Key points
A194 2H may also be permitted in place of A563 DH on some structural bolts, as specified.
Governing standards: ASTM A194/A194M-24; ASTM A193/A193M-24; ASTM A320/A320M-24. Editions shown are the latest confirmed as of September 2026. The drawing and the
governing standard always take precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-EE51B1 · thefastenerapp.com/fastener-guide/technical-reference/astm-a194-high-temperature-nuts · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
