Cross-system equivalents
Cross-system grades are nearest counterparts, not drop-in substitutes. Chemistry and mechanical envelopes overlap but are not identical — where a design code names a grade, order that grade. Final selection should be confirmed by your project engineer against the governing code.
| Standard system | Grade designation |
|---|---|
| ASME / ASTM | A420 WPL6 · A350 LF2 |
| EN / DIN | P275NL1 (1.0491) |
| JIS | STPL380 |
| GOST | 09Г2С |
| GB | 16Mn / Q345 |
Where this grade belongs
- LNG receiving terminals and regasification piping
- Air separation, ethylene and refrigeration plant
- Cold-climate installations where ambient design temperature falls below −29 °C
- Any line where the design code calls for impact-tested carbon steel
Where it does not
The failures we see most often are not bad material — they are the right material in the wrong service.
- Deep cryogenic service — Below about −46 °C, low-temperature carbon steel runs out of qualification. Austenitic stainless (304L / 316L) is the usual next step, and remains ductile to −196 °C.
- Substituting WPB and claiming equivalence — The chemistry can look similar on a mill certificate. Without the impact test at temperature, the material is not the grade — and it will fail document review.
What we supply in ASTM A420 WPL6
Forms: Butt-weld elbows, tees, reducers and caps (WPL6); weld-neck, slip-on and blind flanges (LF2)
Size range: DN15 – DN1200 fittings, DN15 – DN1500 flanges
Documentation available
- EN 10204 3.1 with Charpy V-notch impact results at −46 °C stated per heat
- Lower test temperatures available on request where the design code requires it
- PED 2014/68/EU with 4.3 material appraisal
- Third-party witness of impact testing by SGS, BV or TÜV
Frequently asked
What temperature is A420 WPL6 rated to?
The standard qualification is Charpy impact testing at −46 °C. Lower test temperatures can be agreed and certified per order where the design code requires it.
What is the difference between A420 WPL6 and A350 LF2?
They cover the same service at the same test temperature — WPL6 is the wrought butt-weld fitting grade, LF2 is the forging grade used for flanges. A low-temperature line normally uses both.
Can I use A234 WPB and just have it impact tested?
Impact testing an ordinary WPB heat does not convert it to WPL6. The grades have different specification requirements; document review will look for the grade designation on the certificate, not just a test result.
Related grades
- ASTM A234 WPB — Carbon steel butt-weld fittings
- ASTM A105 — Carbon steel forgings — flanges and forged fittings
- ASTM A403 WP316 / WP316L — Austenitic stainless steel — 316 / 316L
Full cross-reference across all families: Technical Guide § 2 — Material Grade Equivalents. Pressure class and schedule conversion: § 3 — Pressure Ratings & Pipe Schedules.