Chrome-molyPressure-vessel plateTG-MG-154 · Rev. 1 · October 2026

ASTM A387 Grade 22 Cl.2 — Chemical Composition & Mechanical Properties

ASTM A387 Grade 22 Cl.2 is a chrome-moly alloy steel grade for pressure-vessel plate (UNS K21590, EN / W.Nr ≈ 1.7380 (10CrMo9-10)). It is also known as 2¼Cr-1Mo plate. 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.

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ASTM A387 Grade 22 Cl.2 at a glance

Specification	ASTM A387 Grade 22 Cl.2
Material family	Chrome-moly alloy steel
Product form	Pressure-vessel plate
UNS number	K21590
EN / W.Nr equivalent	≈ 1.7380 (10CrMo9-10)
Also known as	2¼Cr-1Mo plate
Document	TG-MG-154 · Rev. 1 · October 2026

Typical service

Hydroprocessing reactors and high-temperature vessels

Heat treatment

Normalised and tempered, or quenched and tempered

Chemical composition of ASTM A387 Grade 22 Cl.2 (weight %)

C0.05–0.15

Mn0.30–0.60

P0.025 max

S0.025 max

Si0.50 max

Cr2.00–2.50

Mo0.90–1.10

Single values are maximums unless shown as a range or “min”.

Mechanical properties

Tensile strength, min	515 MPa
Yield strength (0.2 % offset), min	310 MPa
Elongation, min	18 %
Tensile strength, max	690 MPa
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 A387 Grade 22 Cl.2

All equivalents

Standard system	Nearest equivalent grade
USA — ASTM / ASME	ASTM A387 Grade 22 Cl.2 · ASME SA-387 Grade 22 Cl.2
USA — UNS	K21590
Europe — EN designation	10CrMo9-10 (EN 10028-2)
Europe — W.Nr	1.7380
Japan — JIS	SCMV4 (JIS G4109)
China — GB / NB	12Cr2Mo1R (GB/T 713.2)
China — old GB designation	12Cr2Mo1R
UK — BS (withdrawn)	BS 1501-622

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
Forged flanges & fittings	ASTM A182 F22 Cl.3
Wrought butt-weld fittings	ASTM A234 WP22 Cl.1
Seamless pipe	ASTM A335 P22
Forged flanges & fittings	ASTM A182 F22 Cl.1
Wrought butt-weld fittings	ASTM A234 WP22 Cl.3

Other chrome-moly alloy steel grades

Chrome-moly alloy steel overview

ASTM A182 F11 Cl.2 ASTM A182 F91 ASTM A234 WP11 Cl.1 ASTM A335 P11 ASTM A335 P91 ASTM A182 F5 ASTM A182 F9 ASTM A182 F12 Cl.2 ASTM A234 WP5 Cl.1 ASTM A234 WP9 Cl.1 ASTM A234 WP91 Type 1 ASTM A335 P5 ASTM A335 P9 ASTM A335 P12

Standards for ASTM A387 Grade 22 Cl.2

All material standards

ASTM A387 EN 10028-2 JIS G4109 GB/T 713.2

FAQ

ASTM A387 Grade 22 Cl.2: common questions

What is the minimum yield strength of ASTM A387 Grade 22 Cl.2?

310 MPa, with a minimum tensile strength of 515 MPa.

What is the carbon content of ASTM A387 Grade 22 Cl.2?

0.05–0.15 %.

What is the UNS number and EN equivalent of ASTM A387 Grade 22 Cl.2?

UNS K21590; the nearest European designation is W.Nr ≈ 1.7380 (10CrMo9-10). Equivalents are close but not identical — check the specification if substituting.

How is ASTM A387 Grade 22 Cl.2 heat treated?

Normalised and tempered, or quenched and tempered.

What is the Chinese (GB) equivalent of ASTM A387 Grade 22 Cl.2?

The nearest Chinese equivalent is 12Cr2Mo1R (GB/T 713.2), formerly 12Cr2Mo1R. Equivalents are close but not identical — compare chemistry and properties before substituting.

What is the JIS equivalent of ASTM A387 Grade 22 Cl.2?

The nearest Japanese (JIS) equivalent is SCMV4 (JIS G4109).

Does Teshi Group supply ASTM A387 Grade 22 Cl.2?

Teshi Group supplies this grade as a stockist and supplier. Send your size, rating and quantity to info@teshigroup.com for a quotation with EN 10204 3.1 certificates.

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