Welding steel pipe from the inside?

Gos · Mar 16, 2021

I know I post some "odd questions" but here I go again.
Does anyone have experience with a system that you can weld 6" Sch 40 pipe from the inside? The obvious question is "why not weld it from the outside?" The answer to that is the pipe is embedded and not accessible from the outside. Ideally, it would be a system for either ID overlays, or butt welds.
Thanks in advance,
Gos

Matt_Maguire · Mar 16, 2021

Yes, I have a BOA-308 borewelder that’ll go down a 2” to 24”dia hole so it can be done. Prepping & doing maybe spendy, and the machine needs a power supply. I’d prolly let mine go with a Lincoln 300mp for $12K or a Thermal Arc Fabricator 250 for $9K.

Video of mine back years back. Boreweld31311.avi - YouTube

Good luck,
Matt

Gos · Mar 16, 2021

Slick system.
Once the elbow is removed, there's only 12" of room from the end of the pipe to a barrier. How much room is needed for this system outside the pipe?

Matt_Maguire · Mar 16, 2021

Gos said:
Slick system.
Once the elbow is removed, there's only 12" of room from the end of the pipe to a barrier. How much room is needed for this system outside the pipe?

Your fooked, they make a little hand crank one that doesn't take much room. Google for a BOA M1 Bore Welding System. You can get a little motor for them also.

Good luck,
Matt

turnworks · Mar 16, 2021

I did a quick down and dirty setup using a cheaper rotary table with a long rod that I turned a morse taper on then attached MIG gun to. Wasn't even close to perfect setup but it got the job done. Had to crank a ton faster than I had previously thought.

It was one of those projects where you had to have 2 look outs to stand guard so no one seen a monster cluster....

DDoug · Mar 16, 2021

Gos said:
I know I post some "odd questions" but here I go again.
Does anyone have experience with a system that you can weld 6" Sch 40 pipe from the inside? The obvious question is "why not weld it from the outside?" The answer to that is the pipe is embedded and not accessible from the outside. Ideally, it would be a system for either ID overlays, or butt welds.
Thanks in advance,
Gos

Weld ?
What process ?
what prep ?
To what quality level ?
To x-ray quality ?

Goff · Mar 16, 2021

check out "cutting edge engineering" on YouTube. He rebuilds heavy earth moving machinery. He has a similar machine to Matt's.

Peter from Holland · Mar 17, 2021

The OP states he needs to weld inside a pipe Not a bore
So I suspect this device will not reach far enough inside the pipe

Peter

Scottl · Mar 17, 2021

You say the pipe is "imbedded". If it's in concrete be very careful. Concrete tends to retain moisture and if it turns to steam from the heat you can get a steam explosion which will send pieces flying with serious force.

At a minimum, keep your distance and wear safety glasses and other PPE.

gbent · Mar 17, 2021

Can you connect the pipes with a Dresser coupling? If it must be a welded connection, a slip sleeve should work. It fits the outside of the existing pipe, and allows a lap weld rather than a butt weld. A lap weld will be easy to do inside a 6" pipe. Then the new piece is slid inside the sleeve and again its a lap weld, but this one is on the outside so the length of your new pipe doesn't matter.

Milland · Mar 17, 2021

How about thermite welding?

Railroad thermite welding - YouTube

Safety would have to be strongly considered, and something like a ceramic form might be needed to contain the thermite as it was packed into place. And if a clear bore was needed, some post-welding grinding would have to be done.

If thermite is out, how about friction welding (not kidding)? Setup would be tricky, and likely expensive, but I bet it could be done with some ingenuity.

Let's think outside the box, people! Down with the tyranny of old-fashioned MIG, TIG, and stick wankery!

Gos · Mar 17, 2021

Still trying to attach pictures.

Gos · Mar 17, 2021

DDoug · Mar 17, 2021

Gos said:
View attachment 316685 View attachment 316686 View attachment 316687

Is this at the local Turd plant ?

Gos · Mar 17, 2021

The piping is embedded through a series of steel plates that make the outside inaccessible. Once the elbows are off, you have enough room to either put your head over the hole, or insert your arm but not both.
The idea is to repair cavitation that's about 18" deep.
You can't remove it.
You can't make more room above it.
You can't sleeve it.

FUN TIMES!

Peter from Holland · Mar 17, 2021

Iam thinking rubber hose Rubber is wearresistanse Also the diam of thehose getss smaller with the vacuum of cavitation eliminating it I could see 2 steel ring holding the rubber hose Bolted in place from the outside ifthat is accesable at least Another option is to bolt in place two halves Anywhere where the pipe is accesableyou can putsome boltsin Even flanged ones is a option if you can remake the clamps or reduce the thicknes of the flanges on the elbow

Peter

Gos · Mar 17, 2021

200MW Hydro

Gos · Mar 17, 2021

Peter from Holland said:
Iam thinking rubber hose Rubber is wearresistanse Also the diam of thehose getss smaller with the vacuum of cavitation eliminating it I could see 2 steel ring holding the rubber hose Bolted in place from the outside ifthat is accesable at least Another option is to bolt in place two halves Anywhere where the pipe is accesableyou can putsome boltsin Even flanged ones is a option if you can remake the clamps or reduce the thicknes of the flanges on the elbow

Peter

Can't sleeve it as it would reduce flow too much, and only the one end is accessible.

Gos · Mar 17, 2021

I appreciate all the thoughts and suggestions.
Thanks one and all.
Gos

Milland · Mar 17, 2021

Gos said:
I appreciate all the thoughts and suggestions.
Thanks one and all.
Gos

Let us know what you finally do.

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