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 | A403 WP316 / WP316L |
| EN / DIN | 1.4401 / 1.4404 |
| JIS | SUS316 / SUS316L |
| GOST | 03Х17Н14М3 |
| GB | 022Cr17Ni12Mo2 |
Where this grade belongs
- Chemical and petrochemical process piping
- Coastal and marine installations, brackish water service
- Pulp and paper, textile and dyeing plant
- Pharmaceutical and food process where cleanability and chloride resistance both matter
Where it does not
The failures we see most often are not bad material — they are the right material in the wrong service.
- Full-strength seawater at temperature — 316L still has a finite pitting resistance (PREN in the mid-20s). For seawater cooling and desalination duty, duplex or super duplex is the correct move.
- High-chloride stress corrosion cracking risk — Austenitic grades are susceptible to chloride SCC above roughly 60 °C. Duplex grades resist it far better.
- Assuming it is a drop-in for 304 pricing — The molybdenum makes 316L materially more expensive. Specify it where chlorides justify it, not by default.
What we supply in ASTM A403 WP316 / WP316L
Forms: Butt-weld elbows, tees, crosses, reducers and caps; forged flanges in the matching A182 F316 / F316L grades
Size range: DN15 – DN1200 fittings, Sch 5S through Sch 80S and heavier on request
Documentation available
- EN 10204 3.1 material test certificate traceable to the heat number
- Intergranular corrosion testing to ASTM A262 Practice E on request
- PMI (positive material identification) on request
- NACE MR0175 / ISO 15156 compliance where sour service is specified
- PED 2014/68/EU with 4.3 material appraisal
Frequently asked
What is the difference between 316 and 316L?
Carbon content. 316L is the low-carbon variant and resists intergranular corrosion better after welding. For welded piping, 316L is the normal specification.
Is 316L good enough for seawater?
For intermittent or diluted exposure, often yes. For continuous full-strength seawater — cooling water, desalination, firewater — 316L is generally under-specified and duplex S31803 or super duplex S32750 is the appropriate grade.
What is the EN equivalent of A403 WP316L?
1.4404 is the counterpart usually referenced; plain 316 corresponds to 1.4401.
Related grades
- ASTM A403 WP304 / WP304L — Austenitic stainless steel — 304 / 304L
- Duplex S31803 / S32205 & Super Duplex S32750 — Duplex and super duplex stainless steel
- ASTM A403 WP321 / WP347 — Stabilised austenitic stainless steel
Full cross-reference across all families: Technical Guide § 2 — Material Grade Equivalents. Pressure class and schedule conversion: § 3 — Pressure Ratings & Pipe Schedules.