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Partial Replacement of Tank Shell Course - not full height

Partial Replacement of Tank Shell Course - not full height

Hi guys, no matter how much experience you have, there is always room for a difficult to answer question... Here it goes:
Existing Tank made of 3 courses, each one about 2 meters in height, the first course thickness is 1", each course made of 3 plates in full length. Material Carbon Steel, no PWHT required.
The tank demonstrates corrosion on the bottom plates, annular ring and 1st shell course, from bottom up to a level of about 800mm, all round.
Client requests (suppose for economic reasons) that the first course to be substituted, but not in its entirety, but for about 1 meter from bottom, at full circumference. In other words, cut the first shell course at 1 meter (progressively), add a new plate of 1 meter width, do that for the entire circumference, and at the end we will have a new shell course of 1 meter height, and a new circumferential weld at 1 meter height.
After checking with API 653, I found no information if this practice is approved or not, I personally do not like it, but Code does not describe it in the foreseen methods, nor forbids it...
Any ideas?

Only best result in absolutely necessary time

RE: Partial Replacement of Tank Shell Course - not full height

Can you maintain any required weld clearances between the round seam and the nozzle/manway repads, etc.?

RE: Partial Replacement of Tank Shell Course - not full height

This procedure is done all the time. As JStephen notes, you have to check the location of nozzles and manways to be sure there is clearance from the tank seams.

RE: Partial Replacement of Tank Shell Course - not full height

Thank you both for your replies, and sorry for my late reply...
So, weld clearance is the main issue as I understand... Common practice would be satisfied with a 50mm (2") weld clearance, and I think we do have it.
Just for the record, it was decided by Client to substitute totally the lower course, which of course is a better solution, technically, and especially for us, the contractor...
Once again, thanks!

Only best result in absolutely necessary time

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