Cross over fittings

Coldman · Tue Dec 16, 2014 6:13 pm

This is the most thankless job I've had to do in a while. We can't get NPT to BSPP cross over fittings here in Oz it seems, I tried everywhere - engineers supplies, hydraulics, A105 3000# manufacturers all manner of cattledogs (catalogues haha). I shouldn't even have had to do it. But you know if I couldn't weld I'd be stuffed round about now - how good is that.

The 1/4 x 1/4 fittings I was able to run a cold tap - ok. The 1/4 x 1/8" I had to use the "hot tap". Its ugly but it works.
Used 1.6mm er70s-2, 2.4mm Lanthenated tungsten. 125amps max on the pedal. Ground off the zinc plating first. The sockets and 1/8 nipples are hydraulic fittings, the 1/4 nipples are 3000#.

These adapters are needed to fit pressure transducers with British threadform to a screw compressor assembly with manifolds tapped with American threadform.

I know that a couple of them look like they are on the piss. I tried to straighten them with a copper mallet but they would not budge. I couldn't use a steel hammer on the threads and I wasn't about to cut the tack on these little guys and start again and risk damaging the nipple. Like I say its ugly but it works.

: npt (800x450).jpg (46.08 KiB) Viewed 520 times

Tue Dec 16, 2014 9:00 pm

That blows!

I have a handfull in my TIG box. They are "every day" fittings here.

Steve S

Coldman · Tue Dec 16, 2014 10:01 pm

noddybrian · Wed Dec 17, 2014 6:30 am

Wow & I thought things were hard to source here ! - hard to weld round those small fittings my hand - I guess on your application they are not critical - if they were I think I'd just order in a length of hex bar & make them on a lathe - alternative method if available is to helicoil the manifold thread to one that you can source nipples - not sure why BSP would be hard to find though.

Coldman · Wed Dec 17, 2014 4:49 pm

The two big problem contributors are firstly the small size. Anything under 1/2" is not normally stocked. I also needed bspp (parallel thread) which makes it impossible. My local machine shop wanted $65 to turn them up and he is slammed as well. That left me with the hot tap at short notice. Given time I could have looked over your way. ..