Intergranular corrosion testing for non-pressurized parts

[nickypaliwal]

Our client has a 3 phase test separator which has pH2S of 8 mbar and 12000ppm Chlorides. The removable internals proposed is stainless steel however the inlet and outlet lines to separator are DSS.

I understand that the removable internals can be changed if failed and removable internals are non pressurized part.

1) Do we need IGC testing in this case ?

2) Is there any document which limits the use of material for replaceable non-pressurized parts based on H2S and chlorides content? Is it purely based on decision making and can vary ?

 

[nickypaliwal]

Can we select removable internals based on operating conditions and not design conditions















?

 

[Guest102023]

When it comes to SCC and corrosion, the steel doesn't much care whether it is pressurized or not.
If there is no hazard resulting from failure, then it is a question of cost and inconvenience of replacement.
Your conditions are not unknown, what is the industry norm for MOC?

.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[nickypaliwal]

Is it the pressure gradient across the material which allows H2S to harm it more ?

If not, then the non-pressurized parts may also need same qualification standards.

 

[EdStainless]

My though is based on what happens when they fail?
If it causes a forced outage then they should be tested to the same criteria, unless you want to accept liability for the outage.

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P.E. Metallurgy, Plymouth Tube

 

[nickypaliwal]

In this case, the failure can be accepted by a change in the internals with short downtime..however in general is it the pressure gradient or the total pressure in which non-pressurized parts is placed is the criteria ?

 

[mrfailure]

Do your inserts see static stress as they are installed? Is the installed stress high enough to induce SCC in the environment? Remember, pressure is not necessarily the only source of stress.

 

[nickypaliwal]

Leaving aside additional stresses, In general are these internal material affected similarly by pH2S being non-pressurized parts as the pressurized parts ?

 

[SJones]

The IGC test is a quality control test for the manufacture of the stainless steel. It is not related to performance in a chloride containing H2S environment.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

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

 

[nickypaliwal]

Thanks for clarification.. also clarify if HIC, SSC are evaluated on the same scale for pressurized and non-pressurized parts....