bolting materials in sour service

[kissjxp]

Can we use SA193-B6/SA194-6 as the bolting and nut materials for sour water service?

Thanks.

 

[gr2vessels]

kissjp,
There is a standard, NACE MR 0175 developed for engineers assessing the suitability of materials in sour service.
The sour service is a broad definition for a type of corrosive service which has various degrees of concentration, temperature, level of stress, other components like chlorides, acidity (pH), etc... affecting the behaviour of the corrosion resistant materials in this corrosive environment. Refer to Paragraph 5 and 6 of the mentioned standard, but I urge you to read carefuly the entire standard;- you'll be able to assess the service and select the most suitable material based on your own judgement, not of someone else's. It will be rewarding and will open your eyes to a totally new world of corrosion and will offer you the tools available to fight the environment.
Cheers,
gr2vessels

 

[strider6]

In NACE MR 0175 / ISO 15156 part 2 in chap A 2.2.4 Bolting you'll find the requirements for bolting in sour service.
Acceptable bolting materials are ASTM A 193 grade B7M and ASTM A 320 grade L7M.
but as Gr2 said i suggest to read the entire Standard to be sure that you comply with all the requirements.

hope this help

S

Corrosion Prevention & Corrosion Control

 

[TVP]

kissjxp,

The short answer to your question is no. The previous two responses provide some very good advice on this subject.

 

[kissjxp]

Thanks guys.

In fact, I can not use B7M in this case. That's the reason I want to upgrade the bolting materials to B6 or B8.

I read the NACE MR0103 before. I am worried about the hardness of B6, which may be too high to be used. It looks like I can use B8 bolting materials.

 

[TVP]

Do you know if the environment contains chloride ions? If so, then B8 is not appropriate. You would need something like B8M, B8MLCuN, B8MLCuNA, etc. Just out of curiosity, why can't you use B7M?

 

[strider6]

You've to comply with MR0103 or MR 0175 / iso 15156?
I'm not very familiar with MR0103, but i know that there are some different requirement between 0103 and 0175..

S.

Corrosion Prevention & Corrosion Control

 

[kissjxp]

TVP:
No chloride.

The vessel corrosion allowance is 6 mm. Our client spec. requires 12Cr or 18Cr-8Ni bolting materials for internal structures. I am not quite sure whether 12Cr bolting can be used in wet H2S service or not.


Stride 6:
I also read a paper comparing these two standards, Not too much differece for bolting materials.



If stainless steel is used, do I need to worry about the hardness? I want to use B8 CL2 bolting.

Thanks.

 

[TVP]

kissjxp,

12Cr bolting is not appropriate for wet H₂S use. Hardness is specified in ASTM A 193 for B8 Class 2 as 321 HB (35 HRC) max. ASTM A 194 B8 requirement for hardness is 126 to 300 HB (60 to 105 HRB).

 

[kissjxp]

thanks.