ASTM A234 WP11 Cl.1 — Chemical Composition & Mechanical Properties
ASTM A234 WP11 Cl.1 is a chrome-moly alloy steel grade for wrought butt-weld fittings (UNS K11597, EN / W.Nr ≈ 1.7335). It is also known as 1¼Cr-½Mo. This sheet summarises its chemical composition limits, minimum mechanical properties, heat treatment and typical service. Teshi Group manufactures flanges and fittings in this grade.
ASTM A234 WP11 Cl.1 at a glance
| Specification | ASTM A234 WP11 Cl.1 |
|---|---|
| Material family | Chrome-moly alloy steel |
| Product form | Wrought butt-weld fittings |
| UNS number | K11597 |
| EN / W.Nr equivalent | ≈ 1.7335 |
| Also known as | 1¼Cr-½Mo |
| Document | TG-MG-013 · Rev. 1 · October 2026 |
Typical service
1¼Cr-½Mo high-temperature piping
Heat treatment
Annealed or normalized & tempered
Chemical composition of ASTM A234 WP11 Cl.1 (weight %)
Single values are maximums unless shown as a range or “min”.
Mechanical properties
| Tensile strength, min | 415 MPa |
|---|---|
| Yield strength, min | 205 MPa |
| Elongation, min | 22 % |
| Hardness | 197 HBW |
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 A234 WP11 Cl.1
All equivalents| Standard system | Nearest equivalent grade |
|---|---|
| USA — ASTM / ASME | ASTM A234 WP11 Cl.1 · ASME SA-234 WP11 Cl.1 |
| USA — UNS | K11597 |
| Europe — EN designation | 13CrMo4-5 |
| Europe — W.Nr | 1.7335 |
| Japan — JIS | STPA23 / SFVAF11A |
| China — GB / NB | 15CrMoG (GB/T 5310) / 14Cr1MoR (GB/T 713.2) |
| China — old GB designation | 15CrMo |
| UK — BS (withdrawn) | BS 3604 621 |
Equivalents are the nearest commonly cited grades. Chemistry, mechanical properties and testing differ between standards — compare them before substituting one for another.
Same alloy in other product forms
| Product form | Specification / grade |
|---|---|
| Seamless pipe | ASTM A335 P11 |
| Forged flanges & fittings | ASTM A182 F11 Cl.1 |
Standards for ASTM A234 WP11 Cl.1
All material standardsFAQ
ASTM A234 WP11 Cl.1: common questions
What is the minimum yield strength of ASTM A234 WP11 Cl.1?
205 MPa, with a minimum tensile strength of 415 MPa.
What is the carbon content of ASTM A234 WP11 Cl.1?
0.05–0.15 %.
What is the UNS number and EN equivalent of ASTM A234 WP11 Cl.1?
UNS K11597; the nearest European designation is W.Nr ≈ 1.7335. Equivalents are close but not identical — check the specification if substituting.
How is ASTM A234 WP11 Cl.1 heat treated?
Annealed or normalized & tempered.
What is the Chinese (GB) equivalent of ASTM A234 WP11 Cl.1?
The nearest Chinese equivalent is 15CrMoG (GB/T 5310) / 14Cr1MoR (GB/T 713.2), formerly 15CrMo. Equivalents are close but not identical — compare chemistry and properties before substituting.
What is the JIS equivalent of ASTM A234 WP11 Cl.1?
The nearest Japanese (JIS) equivalent is STPA23 / SFVAF11A.
Does Teshi Group supply ASTM A234 WP11 Cl.1?
Teshi Group manufactures flanges and fittings in this grade. Send your size, rating and quantity to info@teshigroup.com for a quotation with EN 10204 3.1 certificates.
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