Pitting on new API5L pipes

[YahyaYusif]

Dear All, I got a question on one of the major issue we are facing with one of the manufacturer.

We procure a pipeline material and during the visit to the mill we found many pitted areas on the pipe prior to the external coating.
Is there a specific method to accept/reject these pipes, i.e. depth of pits. Any international or SHELL standards can help on this issue.

Also the plates were kept for one year due to some contractual issues. We are not sure whether these pits are because of atmospheric corrosion happened on one year or due to poor manufacturing procedure/quality.

Thanks

 

[metengr]

What does the pipe material specification you refer to when purchasing the pipe material require? Workmanship?

 

[weldstan]

You must expect flaws in pipe skelp (plate). Some will open up after forming into pipe. The pipe surface will need to be properly conditioned to accept the coating. Mill slivers, gouges, scabs will occur on the some of the plates. Outdoor storage for a year could lead to moderate corrosion. You need to assure that the pipe minimum wall will be maintained after flaw removal and surface conditioning prior to coating.

 

[YahyaYusif]

Thanks for reply. Actually it is API 5L material. The spec. calls for 0.4 mm maximum pits depth. some pipes are exceeding this limit and hence rejected and they are many. Not sure if we are running into this what would be the percentage of poor workmanship. This is also supported with high rate of HIC test failures. Would a "Failure Analysis" help ?

Yahya

 

[metengr]

First, I would walk away from this mill and find another rather than trying to make this work. Second, I don't believe a failure analysis would help you because you are rejecting the material based on purchase specification requirements. Why waste your time and money? If anything, this analysis should be by the mill or supplier to explain their poor quality control.

 

[YahyaYusif]

As I said, whatever pipes not complying with spec. are rejected. However, it is extremely huge order, thousands of pipes, mostly complying with spec, and close to the depth limit. And the manufacturer didn't even argue with the rejection of non-complaint pipes.

 

[weldstan]

I assume that you ordered miles of pipe from a specific mill and the mill has no problem in replacing all unacceptable material. In which case it would appear that you have no real contract issue. I have more than once had to reject multiple heats of pipe from a mill due to noncompliance with the Specification.

You may wish to seek added compensation should pipe(s) fail during hydro test and possibly extend warenty due to the present extent of noncompying material regarding HIC failures.