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 WP304 / WP304L |
| EN / DIN | 1.4301 / 1.4307 |
| JIS | SUS304 / SUS304L |
| GOST | 08Х18Н10 |
| GB | 06Cr19Ni10 |
Where this grade belongs
- Food, beverage, pharmaceutical and general sanitary process lines
- Water treatment and demineralised water service
- Architectural and general-purpose corrosion resistance
- Cryogenic service — austenitic grades stay ductile to −196 °C
Where it does not
The failures we see most often are not bad material — they are the right material in the wrong service.
- Chloride environments — 304 pits and suffers stress corrosion cracking in chloride service. Seawater, brackish water and coastal atmospheres call for 316L at minimum, duplex where stress and chloride level are both high.
- Sustained 425 – 815 °C without stabilisation — Sensitisation range. Use a stabilised grade — 321 or 347 — for sustained high-temperature service.
- Sour service — Austenitic grades have their own limits under NACE MR0175; the applicable annex and hardness limits must be specified.
What we supply in ASTM A403 WP304 / WP304L
Forms: Butt-weld elbows, tees, crosses, reducers and caps; forged flanges in the matching A182 F304 / F304L 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
- PED 2014/68/EU with 4.3 material appraisal
Frequently asked
What is the difference between 304 and 304L?
Carbon content. 304L is the low-carbon variant, which reduces chromium carbide precipitation during welding and therefore resists intergranular corrosion better in the as-welded condition. For welded fabrication, 304L is the safer default.
Is 304 suitable for seawater?
No. Chlorides cause pitting and stress corrosion cracking in 304. For seawater or brackish service use 316L as a minimum, and duplex S31803 or super duplex S32750 where chloride level and stress are both high.
What is the EN equivalent of A403 WP304L?
1.4307 is the counterpart usually referenced; plain 304 corresponds to 1.4301.
Related grades
- ASTM A403 WP316 / WP316L — Austenitic stainless steel — 316 / 316L
- ASTM A403 WP321 / WP347 — Stabilised austenitic stainless steel
- Duplex S31803 / S32205 & Super Duplex S32750 — Duplex and super duplex stainless steel
Full cross-reference across all families: Technical Guide § 2 — Material Grade Equivalents. Pressure class and schedule conversion: § 3 — Pressure Ratings & Pipe Schedules.