Welding threaded parts

[PSweeney]

i don’t know why but i seem to routinely ruin threaded parts, like tacking captive nuts and more recently an alloy filler neck which after welding galled and stripped its thread. Threads seems to go tight and need chasing. Has anyone got any tips to preserve threads when welding ?

 

[RonA]

When I’m welding captive nuts I screw the bolt in so its end is flush with the top of the captive nut, holding it in place with nut on the other side before welding Also, Used to have problems with the nut going off centre & bolt thread binding on the drilled hole but now use the type of captive nut with a shoulder & drill the hole to suit the shoulder.
RonA

 

[Wallace]

I have use countersunk screws to align the nut with a piece of tube over the thread to protect from weld splatter.

 

[Justme]

If you weld all the way round a nut surely you shrink it too?

 

[Turbo]

Never screw stainless fittings together before welding them, 99% of the time they will gall due to the heat. A small quick tack is ok.

 

[Hood]

Never screw stainless fittings together before welding them, 99% of the time they will gall due to the heat. A small quick tack is ok.

If welding a stainless nut in place I will always use a steel bolt in it to locate, using a stainless bolt, as you say, will end up in tears.

 

[Morris]

I always assume I will need to run a tap through afterwards, so where possible If the nut is for a through bolt I leave the hole in the backing material tapping size.
Just an extra bit of thread.

 

[Munkul]

Never screw stainless fittings together before welding them, 99% of the time they will gall due to the heat. A small quick tack is ok.

Could not be more correct... and I'm sure a few of us have found this out the hard way!

Also never screw stainless parts together while hot.
Also never screw stainless parts together without coppaslip or whatever your preferred lube.
Also the above applies to any metal, it's just good working practice