Specimen preparation in accordance to ASTM G48 Method A

[Naruwan]

Dear All,
according to ASTM G48 Method A (Pitting corrosion test), we are suppose to polish all surfaces of the specimen to a uniform finish until a minimum of A120-grit. Does this applies to test specimens which have welding? Do we have to polish the weldment or leave it as it is. If yes, then are we not testing the original surface condition of the test specimen, specifically the weld cap and weld root?

 

[EdStainless]

If you are using G48 to determine a CPT as a research project then you should grind the samples.
If you are trying to use the general G48 method to verify the corrosion resistance of a real product then DO NOT alter the surfaces. You procedure should make it very clear which way to go.

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Plymouth Tube

 

[Naruwan]

Thanks! Edstainless! I really need someone like you to support my concept! I had been trying to explain to my client (we are from a testing lab) about this but they insist of polishing the welds. Thanks again!

 

[EdStainless]

We use G48-C to test finished tubing. Our rule is that it must pass at 65C in the as-manufactured condition (SEA-CURE).

We also G48-F for testing starting stock and it receives a surface polish to assure uniform condition, and it must pass at 40C.

Different test method and prep for different reasons.

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Plymouth Tube

 

[SJones]

The current general requirement in the oil and gas industry is to grind only the cut faces of the test piece.

Steve Jones
Materials & Corrosion Engineer

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