ASTM A194
Carbon, alloy and stainless steel nuts for high-pressure or high-temperature bolting
Covers carbon, alloy and stainless steel nuts for high-pressure or high-temperature bolting — grades 2H, 4, 7, 8 and 8M.
- Bolting
- ASME SA-194
- 3 grades supplied to it
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is ASTM A194?
ASTM A194 is the specification for carbon, alloy and stainless steel nuts for high-pressure or high-temperature bolting. Nuts are heavy hex to ASME B18.2.2 unless ordered otherwise. Grade 2H (quenched and tempered carbon steel) is the standard partner for ASTM A193 B7 studs; 2HM is the reduced-hardness version for sour service; 8 and 8M are 304 and 316 stainless.
ASTM A194 at a glance
| Products | Heavy hex nuts (and other nut styles on request) |
|---|---|
| Common grades | 2H, 2HM, 4, 7, 8, 8M |
| Dimensions | ASME B18.2.2 heavy hex |
| ASME designation | SA-194 |
How to write ASTM A194 on a purchase order
Name the product, size, material specification and grade, the dimensional standard and the certificate. An example line:
Illustrative only — sizes, tests, inspection level and any project values come from your purchase specification.
ASTM A194 edition and verification status
Which edition we have confirmed, and what is still being checked before any numerical requirement is published here.
| Current edition (publisher listing) | A194/A194M-26 — checked 7 October 2026 |
|---|---|
| Full-text verification | In progress — numerical requirements are published here only after the current text has been reviewed |
| Edition on your order | The edition named in your purchase order or design code governs — confirm it with your enquiry |
What to know before ordering to ASTM A194
The points that decide whether material to ASTM A194 is accepted at inspection.
- 2H nuts are the standard match for B7 studs; 8M nuts match B8M.
- Heavy hex dimensions follow ASME B18.2.2.
- Nickel-alloy nuts are ordered to the alloy bar specification.
How ASTM A194 fits into an order
A purchase order line is only complete when it names the material standard, the dimensional standard and the inspection document. Miss one and the mill, the inspector and the buyer can each read the order differently.
Standards used with ASTM A194
Same family
ASTM A194 — questions buyers ask
What is ASTM A194?
ASTM A194 is the specification for carbon, alloy and stainless steel nuts for high-pressure or high-temperature bolting. Nuts are heavy hex to ASME B18.2.2 unless ordered otherwise. Grade 2H (quenched and tempered carbon steel) is the standard partner for ASTM A193 B7 studs; 2HM is the reduced-hardness version for sour service; 8 and 8M are 304 and 316 stainless.
What is the difference between A194 2H and 2HM?
2HM has a lower maximum hardness so it can be used in H₂S (sour) service under NACE MR0175; it is paired with B7M studs.
Are A194 nuts heavy hex?
Yes, by default they are heavy hex to ASME B18.2.2.
Which nut goes with a B8M stud?
ASTM A194 grade 8M (316 stainless).
Which grades do you supply to ASTM A194?
SS 304, SS 304L, SS 316 / 316L — see the table on this page for the exact product and designation.
What is the current edition of ASTM A194?
The publisher's listing checked on 7 October 2026 shows A194/A194M-26 as the current edition. The edition that governs an order is the one named in the purchase order or design code. Full-text review of the current edition is in progress, so numerical requirements are not published on this page yet.
Do you supply certificates to this standard?
Yes. Material is supplied with mill test certificates to EN 10204 3.1 showing the standard, grade and heat number; 3.2 with third-party inspection on request.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026