How is PREN calculated?
The Pitting Resistance Equivalent Number (PREN) is the standard measurement for corrosion resistance. While basic calculators often ignore Tungsten (W), Sverdrup Steel uses the extended formula required for high-performance alloys.
The Extended Formula
PREN = %Cr + 3.3 × (%Mo + 0.5 × %W) + 16 × %N
Note: PREN is a theoretical indicator. For specific applications involving acids like H2SO4, please consult our technical team.
Why Tungsten (W)?
In Super Duplex grades like UNS S32760, Tungsten is added to stabilize the material and increase resistance to pitting.
| Grade | Typical PREN | Application |
|---|---|---|
| 316L | ~ 24 | Basic corrosive environments |
| Duplex (2205) | ~ 35 | Stress corrosion resistant |
| Super Duplex | > 40 | Severe marine conditions |
| 6Mo / 254 SMO | > 50 | Chemical processing (H2SO4) |
