INDUSTRY
Duplex, super duplex and copper-nickels for desalination and marine service
Chlorides, crevice corrosion, warm seawater: PREN becomes a survival criterion. This is also the industry where the index is most often misused — a PREN of 42.1 does not make an alloy superior to one at 41.9.
2507 · 254 SMO · CuNi 70/30 PREN from heat chemistry EN 10204 3.1 certificates
What you come to us for
A grade that will hold, and increasingly a justification for the choice. Specifications in this industry quote PREN thresholds — 40 for a duplex, 45 for an austenitic in seawater — and the buyer has to demonstrate that the material delivered meets them. That shifts the subject from the grade to the certificate: it is the heat chemistry that decides, not the designation.
Then availability. 2507 and 254 SMO are not everyday stock items at generalist distributors, and this is precisely the case where direct access to European partner stock and to the mill changes the answer.
What we supply
Tube, fittings, flanges and bar in duplex, super duplex, super austenitic grades and copper-nickels, with EN 10204 3.1 material certificates carrying the heat chemistry. Our PREN calculator lets you check the actual value of your heat from that certificate, before receipt if you ask for it in advance.
What we do not do: validate your grade selection on your behalf. PREN ignores service temperature, surface condition and crevice corrosion. We supply the material, its chemistry and the tools to read it; suitability for the medium is your engineering department's call.
Grades in this industry
| Grade | EN | Indicative PREN |
|---|---|---|
| 2507 | 1.4410 | 42–43 ¹ |
| 254 SMO | 1.4547 | 43–45 ¹ |
| CuNi 70/30 | CW354H | does not apply to this family |
¹ usual value from the technical literature, not drawn from a product standard.
The grades listed are the most common in this industry, not a closed list. Every piping grade belongs to one of our nine families; if yours doesn't appear here, it is not outside our scope.
Applicable standards
Seamless duplex and super duplex: ASTM A790, EN 10216-5. Welded duplex: ASTM A928, EN 10217-7. Super austenitic grades: ASTM A312, EN 10216-5. Copper-nickels: ASTM B111, EN 12451. Titanium: ASTM B338.
Frequently asked questions
- Is a higher PREN always better?
- No. It is a comparative index, not a rating. It accounts for neither service temperature, nor crevice corrosion, nor surface condition, nor secondary phases. Two grades with similar PREN can behave very differently in the same basin.
- Can I get the actual PREN of my heat before delivery?
- The EN 10204 3.1 material certificate carries the heat chemistry, from which the actual PREN is calculated. Ask for it at enquiry stage if you want it before despatch rather than with the goods.
- Is 2507 always necessary, or will a 2205 do?
- It depends on the medium and the temperature. 2205 covers brackish water and routine petrochemical service; 2507 earns its place in seawater and severe offshore duty. The cost premium and the more demanding fabrication of super duplex are only justified if the medium requires it.
- Do you supply these grades in small quantities?
- Yes, and it is a common case: grades in this industry are rarely held by generalist distributors, and a requirement for a few metres is handled through our European partner stocks.
Tell us what you need: grade, size, quantity, deadline. Same-day response on a simple enquiry, within 2 to 3 working days on a complex one.
Request a quote →