I needed to reduce the outer diameter pipe

[Sergei Slovenija]

I don't have experience or a ready-made solution for this task. I thought a little and got down to business. Hopefully I'll finish on Tuesday.
I hope from the first part of the video it is clear how I am trying to solve this problem.

How would you solve this problem?

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[minimutly]

I've not watched the vid, but can you not use a bead roller to set the wall in, having first cut a number of reliefs in the reduced section to allow room? A simple calc on diameter difference Vs circumferance should tell you how much to remove, then once achieved tig up the joints?

 

[Sergei Slovenija]

I've not watched the vid, but can you not use a bead roller to set the wall in, having first cut a number of reliefs in the reduced section to allow room? A simple calc on diameter difference Vs circumferance should tell you how much to remove, then once achieved tig up the joints?

The video is less than a minute or so. And I don't have a roller to form the edge of the pipes. This powder-painted (the devil invented it!) stainless steel is quite thick, 1.5 mm. It cannot be straightened with a hammer.

 

[gaz1]

you can do it the simple way cut a bit of tube off and slice the down it for joints and reweld at the one join then you can slot both tubes into each other

for reducing

 

[Sergei Slovenija]

you can do it the simple way cut a bit of tube off and slice the down it for joints and reweld at the one join then you can slot both tubes into each other

for reducing

Making a cone reduction is not a problem. A cylindrical part of reduced diameter is needed.

 

[gaz1]

Making a cone reduction is not a problem. A cylindrical part of reduced diameter is needed.

as explained on the other post to slot it inside the other joint its easier to cut a chunk off and slit it up the side reweld that joint and weld on the outside to reduce the diameter

 

[Screwdriver]

Unclear from your post which part is bigger/smaller. Surely it would be easier to expand the size of the smaller part? Just hit it with a hammer!

 

[Sergei Slovenija]

as explained on the other post to slot it inside the other joint its easier to cut a chunk off and slit it up the side reweld that joint and weld on the outside to reduce the diameter

I have little experience welding thin stainless steel. From what I have welded before, there is a lot of metal shrinkage and warping. I’m not happy with these ugly seams either; I had to weld in a draft from fans among operating equipment + low amperage, the filler rod barely spread (the weld pool was kept “cold”) when welding millimeter gaps. But there were no holes. It will work, it's part of the granule conveyor. But the inside of the pipe is quite smooth, the granule will not cling or tear, a smooth transition.

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[Sergei Slovenija]

Unclear from your post which part is bigger/smaller. Surely it would be easier to expand the size of the smaller part? Just hit it with a hammer!

A useless exercise for stainless steel, IMHO

 

[Screwdriver]

A useless exercise for stainless steel, IMHO

Well, I might suggest the part you wish to work on has already been formed so...

You will need a decent anvil with a horn (that's what the horn is for!) or of course, a makeshift anvil like object. But without seeing the parts you want to fit, it's difficult to be precise. From the above it appears you are lengthening a cylinder which has to remain the same diameter??

Anyhow, I doubt of any of this is news to you so I'm just saying that you can form stainless if/when appropriate.

 

[gaz1]

heres a few alternatives

 

[Sergei Slovenija]

It is done. I smoothed out the welds from the inside with a 40 hertz pulse.

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[Sergei Slovenija]

heres a few alternatives

With soft black steel pipe, this is quite simple and you can always do an intermediate anneal. With a stainless steel pipe, diameter 140 and thickness approximately 1.25, IMHO this is not realistic. Use a hammer to reduce the diameter, without taper, making a step, with a cylinder length of 40 mm... the metal should shrink relatively evenly.