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NACE MR0175 - Allowable Low Alloy Steel Grade

NACE MR0175 - Allowable Low Alloy Steel Grade

NACE MR0175 - Allowable Low Alloy Steel Grade

Good morning to everyone,
i'm new on this Forum.
I'm a mechanical engineer and i'm working in the upstream Oil & Gas industry.
I have a question obout choosing a low alloy steel grade according to NACE MR0175.
The purchaser request a valve body and bonnet in AISI 4130 indicating API6A material class EE-1.5.
Since there isn't this material grade addressed in NACE, i'm sure that I can't choose this grade marking "-1.5" H2S partial pressure limit.

But my question is:
- According to NACE MR0175, wich low alloy steel material grade (or Carbon steel) I can choose to satisfy the customer request "EE-1.5" Mat.Calss??
- Or I can choose any grade respecting NACE hardness requirement and I shall mark EE, without any H2S Partial Pressure Limit (equal to mark "EE-NL")?
- Or I may suggest to the customer for example AISI 4130 Body&Bonnet with fully cladded inlay, with stem i.e. in AISI 410 (limited to 1.5 H2S partial pressure in NACE?

Someone knows any grade of low alloy steel that listed with H2S partial pressure limit, that are in accordance with NACE?

Thank you in advance for the answer.


RE: NACE MR0175 - Allowable Low Alloy Steel Grade

Good morning Mauro,

Please do not post the same question in multiple forums on this site.

Please review API 6A 21st Edition Table 3 for clarification on the EE requirements.

The valve body and bonnet can be 4130 and meet the EE requirement. If you are only supplying the body and bonnet, and not any internals, then 4130 is fine.

The valve bore sealing mechanisms and stems are required to be stainless steel or CRA and may limit your H2S partial pressure rating.

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