ASTM A333 Grade 3 — Chemical Composition & Mechanical Properties
ASTM A333 Grade 3 is a low-temperature carbon steel (ltcs) grade for seamless & welded pipe (UNS K31918, EN / W.Nr ≈ 1.5637 (12Ni14)). It is also known as 3.5 Ni. 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 A333 Grade 3 at a glance
| Specification | ASTM A333 Grade 3 |
|---|---|
| Material family | Low-temperature carbon steel (LTCS) |
| Product form | Seamless & welded pipe |
| UNS number | K31918 |
| EN / W.Nr equivalent | ≈ 1.5637 (12Ni14) |
| Also known as | 3.5 Ni |
| Document | TG-MG-156 · Rev. 1 · October 2026 |
Typical service
3.5 % nickel pipe for −101 °C service
Heat treatment
Normalised, or normalised and tempered
Chemical composition of ASTM A333 Grade 3 (weight %)
Single values are maximums unless shown as a range or “min”.
Mechanical properties
| Tensile strength, min | 450 MPa |
|---|---|
| Yield strength (0.2 % offset), min | 240 MPa |
| Elongation, min | 30 % |
| Charpy V-notch test temperature | −100 °C (−150 °F), 18 J avg, full size |
| Hardness | Not specified |
About low-temperature carbon steel (ltcs)
Low-temperature carbon steel (LTCS) is carbon–manganese steel with fine-grain practice and heat treatment chosen to keep its toughness in cold service. Every heat is Charpy impact-tested at the minimum design temperature, which is what separates LTCS from ordinary carbon steel.
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 A333 Grade 3
All equivalents| Standard system | Nearest equivalent grade |
|---|---|
| USA — ASTM / ASME | ASTM A333 Grade 3 · ASME SA-333 Grade 3 |
| USA — UNS | K31918 |
| Europe — EN designation | 12Ni14 (EN 10216-4) |
| Europe — W.Nr | 1.5637 |
| Japan — JIS | STPL450 (JIS G3460) |
| China — GB / NB | 06Ni3MoDG (GB/T 18984) |
| UK — BS (withdrawn) | BS 3603 503 LT100 |
Equivalents are the nearest commonly cited grades. Chemistry, mechanical properties and testing differ between standards — compare them before substituting one for another.
Other low-temperature carbon steel (ltcs) grades
Low-temperature carbon steel (LTCS) overviewStandards for ASTM A333 Grade 3
All material standardsFAQ
ASTM A333 Grade 3: common questions
What is the minimum yield strength of ASTM A333 Grade 3?
240 MPa, with a minimum tensile strength of 450 MPa.
What is the carbon content of ASTM A333 Grade 3?
0.19 max %.
What is the UNS number and EN equivalent of ASTM A333 Grade 3?
UNS K31918; the nearest European designation is W.Nr ≈ 1.5637 (12Ni14). Equivalents are close but not identical — check the specification if substituting.
How is ASTM A333 Grade 3 heat treated?
Normalised, or normalised and tempered.
What is the Chinese (GB) equivalent of ASTM A333 Grade 3?
The nearest Chinese equivalent is 06Ni3MoDG (GB/T 18984). Equivalents are close but not identical — compare chemistry and properties before substituting.
What is the JIS equivalent of ASTM A333 Grade 3?
The nearest Japanese (JIS) equivalent is STPL450 (JIS G3460).
Does Teshi Group supply ASTM A333 Grade 3?
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.
Related products, data sheets and standards
Carbon Steel Seamless Pipe
Stockist & supplier
View online · PDFTechnical data sheetWeld Neck Flange
OEM manufacturer
View online · PDFTechnical data sheetButt Weld Elbow
OEM manufacturer
View online · PDFMaterial productsASTM A350 LF2 / LF3 Low-Temperature Flanges
Grades, sizes and standards we supply
ViewMaterial productsASTM A420 WPL6 / WPL3 Low-Temperature Pipe Fittings
Grades, sizes and standards we supply
View
Ready to build to spec?
Share your drawing, bill of materials or technical requirements with the Teshi team.