ASTM A320
Alloy and stainless steel bolting for low-temperature service
Covers alloy and stainless steel bolting for low-temperature service, with impact testing — grades L7, L43 and B8/B8M classes for cryogenic use.
- Bolting
- ASME SA-320
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is ASTM A320?
ASTM A320 is the specification for alloy and stainless steel bolting for low-temperature service. L7 (quenched and tempered chromium-molybdenum steel, impact tested at −101 °C / −150 °F) is the common grade; austenitic B8 and B8M classes are also covered. It is the low-temperature counterpart of ASTM A193. Nuts are ordered to ASTM A194. ASME adopts it as SA-320.
ASTM A320 at a glance
| Products | Bolting material — bars, bolts, screws, studs and stud bolts |
|---|---|
| Common grades | L7, L7M, L43, B8 / B8M (class 1 and 2) |
| L7 impact test | −101 °C (−150 °F) |
| Nuts | ASTM A194 grade 4 or 7, impact tested and marked 4L / 7L |
| ASME designation | SA-320 |
How to write ASTM A320 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 A320 edition and verification status
Which edition we have confirmed, and what is still being checked before any numerical requirement is published here.
| Current edition | Not yet confirmed against the publisher listing |
|---|---|
| Full-text verification | In progress — numerical requirements are not published on this page |
| 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 A320
The points that decide whether material to ASTM A320 is accepted at inspection.
- L7 is the low-temperature counterpart of B7.
- Impact test temperature must suit the design temperature.
- Pair with A194 grade 4 or 7 nuts for low-temperature service.
How ASTM A320 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 A320
Same family
ASTM A320 — questions buyers ask
What is ASTM A320?
ASTM A320 is the specification for alloy and stainless steel bolting for low-temperature service. L7 (quenched and tempered chromium-molybdenum steel, impact tested at −101 °C / −150 °F) is the common grade; austenitic B8 and B8M classes are also covered. It is the low-temperature counterpart of ASTM A193. Nuts are ordered to ASTM A194. ASME adopts it as SA-320.
When is A320 L7 used instead of A193 B7?
When the bolting must keep impact toughness at low temperature — L7 is impact tested at −101 °C.
What is the difference between ASTM A320 and ASME SA-320?
ASME SA-320 is the ASME Boiler and Pressure Vessel Code (Section II) adoption of ASTM A320. The technical requirements are usually identical to a specific ASTM edition; pressure-equipment codes call for the ASME designation, and most mill certificates show both.
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