ASTM A335 P1 — Chemical Composition & Mechanical Properties
ASTM A335 P1 is a chrome-moly alloy steel grade for seamless pipe (UNS K11522, EN / W.Nr ≈ 1.5415 (16Mo3)). It is also known as C-½Mo. This sheet summarises its chemical composition limits, minimum mechanical properties, heat treatment and typical service. Teshi Group supplies this grade as a stockist and supplier, and manufactures matching flanges and fittings.
ASTM A335 P1 at a glance
| Specification | ASTM A335 P1 |
|---|---|
| Material family | Chrome-moly alloy steel |
| Product form | Seamless pipe |
| UNS number | K11522 |
| EN / W.Nr equivalent | ≈ 1.5415 (16Mo3) |
| Also known as | C-½Mo |
| Document | TG-MG-137 · Rev. 1 · October 2026 |
Typical service
Carbon-moly steam and process piping
Heat treatment
Annealed, normalised and tempered, or subcritically annealed
Chemical composition of ASTM A335 P1 (weight %)
Single values are maximums unless shown as a range or “min”.
Mechanical properties
| Tensile strength, min | 380 MPa |
|---|---|
| Yield strength (0.2 % offset), min | 205 MPa |
| Elongation, min | 30 % |
| Hardness | Not specified |
About chrome-moly alloy steel
Chrome-moly steels are low-alloy steels with 1–9 % chromium and 0.5–1 % molybdenum. Chromium gives oxidation and sulphidation resistance; molybdenum gives creep strength at high temperature. They are the standard choice for steam and hot hydrocarbon service above the carbon-steel range.
Reference information compiled from the published standard for convenience. It does not replace the current edition of the governing standard, which takes precedence. Verify critical dimensions and properties before design, purchase or fabrication. Teshi Engineers & Sales Promoters (P) Ltd accepts no liability for errors or omissions.
International equivalents of ASTM A335 P1
All equivalents| Standard system | Nearest equivalent grade |
|---|---|
| USA — ASTM / ASME | ASTM A335 P1 · ASME SA-335 P1 |
| USA — UNS | K11522 |
| Europe — EN designation | 16Mo3 |
| Europe — W.Nr | 1.5415 |
| Japan — JIS | STPA12 / SFVAF1 |
| China — GB / NB | 15MoG / 20MoG (GB/T 5310) |
| China — old GB designation | 16Mo |
| UK — BS (withdrawn) | BS 3059-2 243 |
Equivalents are the nearest commonly cited grades. Chemistry, mechanical properties and testing differ between standards — compare them before substituting one for another.
Standards for ASTM A335 P1
All material standardsFAQ
ASTM A335 P1: common questions
What is the minimum yield strength of ASTM A335 P1?
205 MPa, with a minimum tensile strength of 380 MPa.
What is the carbon content of ASTM A335 P1?
0.10–0.20 %.
What is the UNS number and EN equivalent of ASTM A335 P1?
UNS K11522; the nearest European designation is W.Nr ≈ 1.5415 (16Mo3). Equivalents are close but not identical — check the specification if substituting.
How is ASTM A335 P1 heat treated?
Annealed, normalised and tempered, or subcritically annealed.
What is the Chinese (GB) equivalent of ASTM A335 P1?
The nearest Chinese equivalent is 15MoG / 20MoG (GB/T 5310), formerly 16Mo. Equivalents are close but not identical — compare chemistry and properties before substituting.
What is the JIS equivalent of ASTM A335 P1?
The nearest Japanese (JIS) equivalent is STPA12 / SFVAF1.
Does Teshi Group supply ASTM A335 P1?
Teshi Group supplies this grade as a stockist and supplier, and manufactures matching flanges and fittings. Send your size, rating and quantity to info@teshigroup.com for a quotation with EN 10204 3.1 certificates.
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