NACE & Stainless Steel

[Frank1344]

Hello Folks,

Can we have a Stainless Steel (like SS-316L) and be conformed to NACE requirements at the same time?

My confusion is, when using Stainless Steel, don't we already meet the NACE requirements for Sour Service?

Regards,
Frank
Calgary

 

[chaulklate]

Frank,

I think it comes down to hardness values. NACE MR-0175, paragraph 3.5, accepts 316L provided the hardness value is 22 HRC max in the annealed condition. As per Section II Part A, 316L has a maximum hardness value of 217 Brinell or 95 Rockwell B.

The problem here is these are different methods of measuring hardness and I don't know how these values convert and compare. Methinks the maximum range set out by ASME is higher (or vice versa?) than the max range set out by NACE, so the safest bet would be to order your 316L material and specify the maximum hardness to 22 HRC as per the NACE document.

If you find a resource for converting these hardness values, let me know, the last part of my post is speculation.

 

[unclesyd]

A resource for converting hardness values courtesy of an Eng-Tips member, Katmar.

http://www.katmarsoftware.com/uconeer.htm

 

[chaulklate]

The below link will help convert between HRB and HRC. The way I see it, ASME has a maximum hardness of 17 HRC, NACE has a maximum hardness of 22 HRC. It seems like a no-brainer, but don't lose sight of the other requirements regarding annealing and cold work. Although it may appear as a redundancy, it may be safest to simply order your material c/w NACE certificates.

http://www.efunda.com/units/hardness/convert_hardness.cfm?HD=HRB&Cat=Steel#ConvInto

 

[Frank1344]

Thank you guys.

 

[SJones]

Sorry to be a killjoy; but, everyone above is focusing solely on hardness limits. NACE MR0175/ISO 15156-3 also has environmental limits for austenitic stainless steels. So, how will an alloy supplier also certify the material for the environmental limits? I think it's going to be tricky if one wants to get suppliers to certify materials also against environmental restrictions (unless the material in question is going to be used for compressors, instrumentation, or gas lift/downhole 'stuff').

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[strider6]

I agree with SJones, one thing is a material compliant with NACE requirements (hardness, heat treatments) the other things are the NACE limits for that particular materials. You can have a 316 fully compliants with NACE but that is used above the NACE limits, example 60°C or partial pressure of H2S above 1 bar..) and so on.

S.

http://www.corrosionist.com