Welding Tips and Tricks

I'm working on some 3inch stainless pipe and I need to shape a 20mm by 5mm deep "dent" in a section for clearance
I was going to heat it push it like mild steel but being stainless I don't want to do it this way if there is a better way

Try filling it with sand and using a tool the shape of the dent you want.

weldin mike 27 wrote:Try filling it with sand and using a tool the shape of the dent you want.

We've used the sand method too. Very dry sand, packed in tight and the ends of the pipe capped. We then used heat and formed the pipe to suit.

What is the wall thickness of the pipe, do you know what grade stainless?

TRACKRANGER wrote:

weldin mike 27 wrote:Try filling it with sand and using a tool the shape of the dent you want.

We've used the sand method too. Very dry sand, packed in tight and the ends of the pipe capped. We then used heat and formed the pipe to suit.

What is the wall thickness of the pipe, do you know what grade stainless?

the grade is 304 and wall thickness is 1.6mm

Oh, OK

I was thinking something more heavy walled. This sounds more like tube than pipe

Should be very 'doable'

1,6mm sounds like sch. 5, so, yes, pipe.

The sand method is an excellent way to not collapse pipe where you don't want it to kink, and heating 304 to the brown to dull red range to form it will have no adverse effects. If the heat-affected zone brushes back to "shiny" without a surface grind, and there's no "sugar" on the back side, you've done little to no harm.

Steve S

it's a dent, one dimension is missing but i'd guess it's 7/32 deep by 25/32 long; (app). hit it with a hammer or use an air chisel with flattening attachment. lol sand is a PIA and hardly ever, if ever, necessary. filling a tube of unknown length with sand, welding a cap on both ends and then cutting the caps off, emptying the sand and cleaning up the ends seems like a lot of work for what amounts to a ding the size of a hammer head.

before I did all that, if I had to, I would just cut it in two places push down and weld.

angus wrote:it's a dent, one dimension is missing but i'd guess it's 7/32 deep by 25/32 long; (app). hit it with a hammer or use an air chisel with flattening attachment. lol sand is a PIA and hardly ever, if ever, necessary. filling a tube of unknown length with sand, welding a cap on both ends and then cutting the caps off, emptying the sand and cleaning up the ends seems like a lot of work for what amounts to a ding the size of a hammer head.

before I did all that, if I had to, I would just cut it in two places push down and weld.

There's some good sense, without over-thinking it and making more work than needed.

Steve S

Otto Nobedder wrote:

angus wrote:it's a dent, one dimension is missing but i'd guess it's 7/32 deep by 25/32 long; (app). hit it with a hammer or use an air chisel with flattening attachment. lol sand is a PIA and hardly ever, if ever, necessary. filling a tube of unknown length with sand, welding a cap on both ends and then cutting the caps off, emptying the sand and cleaning up the ends seems like a lot of work for what amounts to a ding the size of a hammer head.

before I did all that, if I had to, I would just cut it in two places push down and weld.

There's some good sense, without over-thinking it and making more work than needed.

Steve S

Agreed
But we all learned more about the best approach as the thread progressed, especially the bit about the wall thickness and the grade.

If you care about appearance, put a rod transverse to the pipe and whack on that, gives you less tooling marks and blends the dent better.

find a socket measuring just under 20 mm and put it
in a press.
clamp as needed.