Bolt material for high temperature and H2S

[PAN]

Refer to NACE MR0175, acceptable bolt material for H2S service is A193-B7M.

In case of high temperature, A193-B16 should be better for strength concern. However, A193-B16 is not indicated in NACE MR0175.

Which is suitable material for high temperature and H2S service? Please comment.

 

[SJones]

Here you face a dilemma: if the bolts don't comply with A.2.1 you either go back to those that do and derate the equipment; or, you go for those that don't and prove their resistance by testing or documented experience.

Steve Jones
Materials & Corrosion Engineer

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

 

[chaulklate]

This is not my comfort area, so let's see if someone else can back this up or shut it down.

Can you consider a stainless system like A-193-B8M? My "charts" indicate them to be good in corrosive environments and up to 1500 deg F. MR-0175 para 3.5.1 accepts austenitic stainless steel to within 22 HRC maximum and these studs are austenitic.

Can anyone reinforce this??

 

[SJones]

Assuming that we are discussing 'exterior' bolting that will only be exposed to H2S containing fluid during a loss of containment, then the above option is feasible if the necessary strength and temperature ratings can be achieved with 22HRC material. If it's a continuous immersion scenario, with mixed materials - it probably would not be advisable.

Steve Jones
Materials & Corrosion Engineer

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