Peaking and Banding per API 653

[jramosjr]

We are rehabilitating a tank as per API 653 and when the door sheet (cut by others) was re-installed, the welding produced a localized deformation (banding) on the top horizontal seam of the door sheet of 3/4". The project inspector claims that the banding should be not more than 1/2" as per API 650 Section 7.5.4. API 653 Section 9, which covers tank repairs and/or alterations does not specify dimensional tolerances for peaking and banding. However, API 653 Section 10.5.5 gives dimensional tolerances for peaking (1/2") and banding (1"), but they apply for tank reconstructions. Is it correct to refer to API 650 for the peaking and banding tolerances? To me, these only apply in the fabrication of new tanks. Or can we claim that since API 653 Section 9 does not inlcude tolerances, this requirement does not apply? Why is that for recontructed tanks, API 653 Section 10.5.5 does inlcude a banding tolerance as high as 1"? I'm afraid that if we are asked to repair this, more heat from gouging and re-welding will make matters worse. Your opinin is greatly appreciated.

Jorge L. Ramos, Jr., MSCE, PE
Alonso & Carus Iron Works, Inc. (

http://www.alonsocarus.com)

Euro-American Steel Co., Inc. (

http://www.euroamericansteel.com)

 

[Kiwi2671]

Jorge,
You are in a difficult position and the only person who can adjudicate is the Owner or the Owners Engineer.
The project inspector is only giving you his opinion.

9.1.1 The basis for repairs and alterations shall be an API
Std 650 equivalence

9.2.3.4 To reduce the potential for distortion of an existing
tank due to welding a replacement plate into an existing
tank shell, fit-up, heat input, and welding sequence must be
considered.

Clause 9.1.1 seems (IMHO) to state you must comply with API 650.

However, API 650 Section 7.5.4 gives you a max of 1/2" and API 653 Section 10.5.5 gives you a max of 1".

It appears the code committee has given some leniency (additional 1/2") for reconstructed tanks based on the additional welding in the horizontal position - which is your situation. (Why the criteria for peaking is the same in both standards but banding is different - I have no idea)
The fact that the door sheet was made by someone else should have had no effect on the banding - I would be investigating why the welders/supervisors didn't follow the recommendations of 9.2.3.4
Good luck and I hope you get it resolved.
Regards,
Kiwi