Standard of Pipe in a new condition

[cilacap]

Dear all friends,
We have a contract to Built a Boiler Cap. 110 t/h complete with its supporting equipment and pipe lines with a local contractor. We are now in phase constructions and some materials already in site. We had a problem when pipes come in site, while we inspected them by visual, mostly pitting corrosion appear on internal pipes surface.We said to pipe supplier,that we rejected many pipes caused of corrosion pitting. However, the supplier could not accept our argument,and judge that conditions were normal, and denied to subtitute with other new ones, and . Now, we are in conflict due to we have no standars parameter to judge whether the pipes shall be accepted or rejected. At present I just refer to new contions means everything is smooth. In accordance with my problem, for to you all, please help me to give advices.

Appreciate for your attention.

Thanks and Regards

Ari Dwikoranto

 

[StressGuy]

You'll want to start with the engineering design. Somewhere along the way, calculations were done to determine what the minimum thickness of those pipes have to be in order to contain the pressure. A corrosion allowance is applied on top of that (as perhaps an external allowance as well).

The engineers should be able to give you a minimum acceptable wall thickness value. You should then be able to take readings at the pit locations. If you sample several lines and find the wall thickness at the pits is below the design requirements, that would give you a pretty strong case for rejecting the batch.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[NozzleTwister]

Refer to standards to which you bought the pipe. These standars should define the acceptance criteria for workmanship and defects.

For example, refer to ASTM A106, Section 18 for piping that conforms to ASTM A106. Accetable/non-acceptable pitting is defined. If not A106, then refer to the applicable standard.

Good luck,

NozzleTwister
Houston, Texas

 

[cilacap]

Thank you and appreciate for your responds. I had read ASTM A106, and specifically on sec. 18 about Workmanship, Finish and Appearance. Nevertheless, in my opinion the problem is different. ASTM cites the imperfections caused by workmanship, but in my case, the problem caused by environment pitting corrosion on pipe internal surface. The corrosion attacked on large area of pipe. Cleaning by rotation wire brushing had been done, and the results some pipes be clean and remains pipes corrosion still visible on pipe surface. The specification of pipes mostly is ASTM 106.
Therefore, I am still hoping for your advice more.
Thank you