Tool
PREN calculator
PREN = %Cr + 3.3 × %Mo + 16 × %N. Enter a heat analysis from a mill certificate to check its pitting resistance.
PREN of the grades we supply
| Grade | PREN (approx.) |
|---|---|
| SS 304 | 18 |
| SS 304L | 18 |
| SS 321 | 18 |
| SS 347 | 18 |
| SS 316 / 316L | 24 |
| SS 310 / 310S | 25 |
| Inconel 825 | 31 |
| SS 904L | 35 |
| Duplex 2205 | 35 |
| Super Duplex S32760 | 41 |
| Super Duplex 2507 | 42 |
| Inconel 625 | 51 |
| Hastelloy C22 | 65 |
| Hastelloy C276 | 68 |
PREN — questions
What is PREN?
The Pitting Resistance Equivalent Number estimates resistance to pitting corrosion from chemistry: PREN = %Cr + 3.3 × %Mo + 16 × %N. Higher is better.
What PREN is needed for seawater?
A PREN of 40 or more is the usual requirement for seawater service, which is why super duplex (2507, S32760) and nickel alloys are used there.
Does PREN apply to nickel alloys?
Only as a rough guide. The formula was developed for stainless steels; for nickel alloys, critical pitting temperature data is more reliable.
India · Gulf · South-East Asia · South America · Europe · USA · UKNeed a grade with PREN above 40? Ask us.
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