Threaded Connections - Plant Piping (Sour Service).

[S.G]

Dear All,

Are threaded connections (for example, injection quills) allowed/acceptable for a highly sour gas service (20% H2S)?

Thank you.

 

[TugboatEng]

That would strongly depend on the material. Is your material subject to crevice corrosion or stress corrosion cracking? Theses create crevices and don't always share load evenly.

 

[SJones]

“Allowed/acceptable” will be dependent upon the policies and experience of the end user.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[LittleInch]

Which code are you using?

ASME B 31.3 section314 has guidance and recomeds only for Normal service and in some case Category D fluids.

A 20% H2S service sounds like a toxic service to me and I wouldn't do it uness there was no option and then possibly seal weld it.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[S.G]

Hi LittleInch,

ASME B31.3

 

[LittleInch]

Then see section 314 and make your own judgement based on their recommendations or requirements.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[S.G]

Thank you, LitteInch. Much appreciated.

 

[1503-44]

Asking for trouble.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[SJones]

Would the OP care to clarify the specific application as the focus on ASME B31.3, 314 seems to be more for threaded joints as opposed to the indication of injection quills where even hydraulic fittings may contain some threaded components that will not be avoided in any service.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[GD2]

Op,
20% H2S service will fall under Category M Fluid. Refer to Chapter VIII Part 4 and go from there.
Threaded connections can't be avoided in any category fluid but the Code provides limitations and specific rules for Severe Cyclic Condition and Cat M fluid.

GDD
Canada

 

[mk3223]

It sounds that the joint connection of the injection quill in the example isn’t complied with your company piping spec of the H2S service. Or, are these threaded joints in the existed piping from the ancient plant?

There are many lessons learnt regarding the H2S incident or the leaking of the piping threaded joint. It’s really sad to learn the incident of the H2S leaking through a threaded joint again.

 

[georgeverghese]

In my old OpCo, threaded connections are strictly not permitted for flammable or toxic fluid service.

 

[S.G]

Hello Steve,
Corrosion chemical - injection quill.

 

[SJones]

@S.G.

Would you care to elaborate where a threaded element is exposed to the H2S containing fluid in the selected quill?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[S.G]

Hi Steve,
It is a corrosion coupon - Retrievable through an access fitting.

 

[GD2]

Threaded joints in H2S service are normally limited to instrument connections. You can't avoid it.

GDD
Canada

 

[SJones]

Hydraulic fittings will be a positive, but really, there should be a rethink about access fittings in a system with 20% H2S.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.