ASTM A335
Seamless ferritic alloy steel (P-grade) pipe for high-temperature service
Covers seamless ferritic alloy steel pipe for high-temperature service — the chrome-moly "P" grades such as P5, P9, P11, P22 and P91.
- Pipe & tube
- ASME SA-335
- 2 grades supplied to it
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is ASTM A335?
ASTM A335 is the specification for seamless ferritic alloy-steel pipe for high-temperature service — the chrome-moly "P" grades. P11 (1¼Cr-½Mo), P22 (2¼Cr-1Mo), P5, P9 and P91 (9Cr-1Mo-V) are used in power plants, refinery heaters and hydrogen service. Matching fittings are ASTM A234 WP grades and flanges ASTM A182 F grades. ASME adopts it as SA-335.
ASTM A335 at a glance
| Product | Seamless alloy steel pipe |
|---|---|
| Common grades | P5, P9, P11, P22, P91 |
| P11 / P22 strength | Pending current standard text |
| Sizes | ASME B36.10 |
| ASME designation | SA-335 |
How to write ASTM A335 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 A335 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 A335
The points that decide whether material to ASTM A335 is accepted at inspection.
- P11 (1¼Cr-½Mo) and P22 (2¼Cr-1Mo) are the common grades for steam and hot-oil lines.
- Matching fittings are ASTM A234 WP11 / WP22 and flanges ASTM A182 F11 / F22.
- Post-weld heat treatment requirements come from the design code, not A335.
Grades and products we supply to ASTM A335
| Grade | Product | Designation on the certificate |
|---|---|---|
| ASTM A335 P11 | Pipe & Tube | ASTM A335 P11 |
| ASTM A335 P22 | Pipe & Tube | ASTM A335 P22 |
How ASTM A335 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 A335
Same family
ASTM A335 — questions buyers ask
What is ASTM A335?
ASTM A335 is the specification for seamless ferritic alloy-steel pipe for high-temperature service — the chrome-moly "P" grades. P11 (1¼Cr-½Mo), P22 (2¼Cr-1Mo), P5, P9 and P91 (9Cr-1Mo-V) are used in power plants, refinery heaters and hydrogen service. Matching fittings are ASTM A234 WP grades and flanges ASTM A182 F grades. ASME adopts it as SA-335.
What is the difference between P11 and P22?
P22 has more chromium and molybdenum (2¼Cr-1Mo vs 1¼Cr-½Mo), giving more strength and oxidation resistance at higher temperatures.
Is A335 pipe seamless only?
Yes, A335 covers seamless pipe.
Which grades do you supply to ASTM A335?
ASTM A335 P11, ASTM A335 P22 — see the table on this page for the exact product and designation.
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