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TOPIC: Butt welding of NPS 2 Sch 40 pipe and fittings vs. Sch 80

7 years 3 weeks ago #8297

  • Flowr8
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I have just been made aware of a mid-project change order requiring that all NPS 2 Sch.40 butt weld carbon steel pipe and fittings be changed to Sch. 80 due to welding problems encountered by the pipe spooling fabricators. Does anyone with a welding background have a comment on this? The difference in wall thickness between NPS 2 Sch. 40 and NPS 2 Sch. 80 is 0.064" (1.63mm), or approximately 1/16th of an inch. I've worked on many projects for several decades where NPS 2 Sch. 40 butt weld has been the norm and this is in our piping specs. I find it hard to understand why it would be such a problem now so as to warrant a change in the middle of a project.

My understanding on this is that it is a done deal approved by project management, but for my own edification I'm curious about what your expert thoughts may be on the subject.

Re: Butt welding of NPS 2 Sch 40 pipe and fittings vs. Sch 8 7 years 3 weeks ago #6812

  • Jop
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Some of my career was spent as the Engineering Manager in a Pipe Fabrication Shop in California.

This request does not make any sense to me. There must be more to the story that they (the Client) are not telling you.

What is the status of the Isometrics at this time?

If they are Issued, there could be big back charges from the Shop/fabricator for material.

If you are using PDMS or PDS or some other like program where the material/Schedule is imbedded in the system then you need to calculate the man hours to make all the changes and submit a Change Order and get it approved before you make the actual changes.

Think it through real carefully. Depending on where you are in the process the added costs may be small or large. No matter, there are changes which result in cost additions.
Do it once and Do it Right
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