[claytski]

Hi,

I do a lot of sch 10 SS pipe welding for custom equipment I fabricate as an OEM. I am more of a welder by trial by fire than training. I have spent days weeks months welding and my sales are outgrowing my capacity at the moment. I will need to outsource some of the welding to a local job shop. I can draw the pieces and parts I need welded with autocad, and provide shop drawings, etc. However, I know that the stainless changes dimensions when heated. Is there a "rule of thumb" or some information you all could point me to that may reference the size change per weld joint? The piping is 1.5" and I weld on butt joint tees, elbows, half couplings, etc etc. I have a feel for the expansion properties of the metals, but I would like formal literature/rules of thumb just so I can incorporate those things into shop drawings.

Thanks in advance guys.

[weldin mike 27]

Hey,

One thing I have heard about piping was that it can shrink around 2mm per joint, but that was bigger bore (150mm) steel. Whilst the small pipe will move less, being stainless, its movement (mainly shrinkage) will be greater compared to other metals.

Mick

[Mongol]

I also weld a lot of sch 10 stainless steel pipe.

To get things started when we measure pipe for cuts we never take out for the gaps and it always ends up the overall length we need. The typical gap here is 1/8in.

When fitting elbows make sure to tack it out of square. It will pull more at the throat so by the time you're done welding it's square. I'm sure there's some science reason why, but I just know that it does.

If you have to drill a hole on one side of the pipe that is to be welded try tacking a piece of bar stock/plate to the backside in order to mitigate distortion. It's going to happen regardless, but it will help. You're most likely going to have to use a oxyfuel torch to heat up the back side in order to draw it back to square, or at least close enough. AWS has a recommended procedure for this.

I don't know of any formal literature off the top of my head, but the PIpe FItter's Blue Book is pretty helpful.

Hope this helps some. Good luck.

[Otto Nobedder]

I also weld a lot of sch 10 stainless steel pipe.

To get things started when we measure pipe for cuts we never take out for the gaps and it always ends up the overall length we need. The typical gap here is 1/8in.

When fitting elbows make sure to tack it out of square. It will pull more at the throat so by the time you're done welding it's square. I'm sure there's some science reason why, but I just know that it does.

If you have to drill a hole on one side of the pipe that is to be welded try tacking a piece of bar stock/plate to the backside in order to mitigate distortion. It's going to happen regardless, but it will help. You're most likely going to have to use a oxyfuel torch to heat up the back side in order to draw it back to square, or at least close enough. AWS has a recommended procedure for this.

I don't know of any formal literature off the top of my head, but the PIpe FItter's Blue Book is pretty helpful.

Hope this helps some. Good luck.

I agree completely, and will add to expect a 90* to shrink 5% more on the inside than the outside.

Steve S