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> Maching after Welding
post Mar 2 2020, 11:42 AM
Joined: 2-Mar 20


This is my first post, so I hope someone can help with my question.

We are a small manufacturing company and we build flanged spool pieces which then get machined and honed into flow meters which require a very smooth, round and well finished bore. We have been using slip on flanges, on an undersized pipe, with two welds on each, which we pressure test, then finish machine the final bore.

To reduce welding costs, we are thinking of switching to weld neck fllanges, but are concerned that we may no get a complete and high quality full pen weld through into the bore, which can then be machined out for a perfect finish. Is this an unfounded concern?

We're wondering about using say schedule 120 or XS flanges, welded to undersized pipe, then machine it back out to the equivalent of sched 80, after welding and pressure test.

Is this an acceptable practice?

Any pointers as to the minimum schedule we should use to get a complete weld that can be machined back to sched 80 and give an unblemished finish in the honed bore.
Technic Al
post Mar 2 2020, 06:23 PM
Joined: 14-Oct 03

There are so many different influences to take into account. To be honest, "if it aint broke dont fix it" is a truism that applies to welding more than most.

What welding process are you using?
What are the actual measurements?...need to know the dia to know the schedules.
What material is it?

Drawings make it a lot easier but from your description it sounds to me that your "new" way could be a lot less accurate than your current method.
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