EN 10253-2 Type B buttweld pipe fittings for liquefied natural gas (LNG) terminals, liquid nitrogen (LN₂), liquid oxygen (LOX), liquid argon (LAr), and other cryogenic process systems. Austenitic stainless steel grades 304L and 316L remain fully ductile at cryogenic temperatures down to −196°C — the key property that makes them the standard material for liquefied gas piping worldwide.
Carbon steel, low-alloy steel, and ferritic stainless steels have a body-centred cubic (BCC) crystal structure. At temperatures below approximately −30°C (for carbon steel) to −60°C (for low-alloy steels), they undergo a ductile-to-brittle transition — impact toughness drops from >100J to <5J. Catastrophic brittle fracture is the result. These materials cannot be used for LNG (−162°C) or liquid nitrogen (−196°C) service.
Austenitic stainless steels (304L, 316L) have a face-centred cubic (FCC) crystal structure. FCC metals do not exhibit a ductile-to-brittle transition — toughness actually increases slightly as temperature falls. Charpy V-notch impact energy at −196°C typically exceeds 100J for solution-annealed 304L/316L. This is why austenitic stainless steel is the universal standard for cryogenic piping systems worldwide.
| Service | Grade | W.Nr. | Design Temp | Note |
|---|---|---|---|---|
| LNG transfer piping (−162°C) | 304L | 1.4307 | −196°C | Clean LNG — no corrosives; 304L cost-optimal |
| LNG storage / vapour return | 304L | 1.4307 | −196°C | Same selection as transfer piping |
| Liquid nitrogen (LN₂), −196°C | 304L | 1.4307 | −196°C | Standard for industrial LN₂ piping |
| Liquid oxygen (LOX), −183°C | 304L / 316L | 1.4307 / 1.4404 | −196°C | LOX clean-service; oxygen-compatible grade required |
| Liquid argon (LAr), −186°C | 304L | 1.4307 | −196°C | Inert gas — 304L standard |
| Cryogenic + chloride (utility loop) | 316L | 1.4404 | −196°C | 16L when chloride in secondary fluid |
| LNG sendout (ambient after vaporisation) | Carbon steel | — | Ambient | Standard CS once gas is warm |
The primary cryogenic piping grade for LNG, LN₂, and LAr. FCC structure maintains >100J Charpy impact at −196°C. No Mo — cost-optimal where chloride corrosion is not a concern (clean cryogenic gas). Solution annealed and impact tested at cryogenic temperature per EN 10253-2.
Full grade page →Specified where cryogenic piping also contacts chloride-bearing fluids or environments. 2–2.5% Mo gives PRE ~24 vs 304L's ~18. Cryogenic impact properties equal to 304L — FCC toughness advantage applies to both grades equally.
Full grade page →EN 10253-2 Type B fittings for cryogenic service require Charpy V-notch impact testing at the design minimum temperature. For LNG at −162°C, test temperature is typically −196°C (a standard cryogenic test point). Results are documented on the EN 10204 3.1 certificate with specimen orientation, test temperature, and average/minimum values. Specify the design temperature when ordering — this determines the test requirement.
EN 10204 3.1 mill certificate. Charpy V-notch impact test report at −196°C. Chemical & mechanical test data. Solution annealing certificate. EN 10253-2 dimensional inspection. PED 2014/68/EU Declaration of Conformity. EN 10204 3.2 (TÜV) available on request.
