[poodle]

I have been around welding all my life(58yrs), have worked in the oilfield ever since high school except for about 3 yrs when I worked at and owned a small welding shop. In that time I have never seen or even heard of welding anything with a backing strap. Now with the internet I see videos of people doing welding test with them all the time. Where are they used in real life. I mean are they left on when the weld is done or are they cut off some how? If they are removed why the heck use them to begin with.
Just a little insight would be appreciated, Steve

[Coldman]

Permanent backing bars are common in pressure vessel manufacture for one.


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[weldin mike 27]

A common joint on tanks that forms a backing bar is called a joggle joint. Where one of the pieces, has a edge bent on it to slide inside the other piece. this forms a backing bar but with one piece. It's how they make propane tanks for cars. I have also seen a 10mm thick on that was for a propane transport truck.

Also any number of structural stuff. The bars are usually only removed on test pieces so they can check if you have done it right.

[poodle]

Thanks guys

[cj737]

Often used in heavy structural stick when there's a gap too wide to bridge. Traps the root. Then the backing is cut loose, and covered from that side. May even be gouged then filled and covered.