Using BSP and NPT fittings

[Night Hawk]

Ok guys is it ok to use BSPP and NPT fittings together? There is a 5 degree pitch different but ive heard that this is not a problem, but im not sure at pressues of about 8bar?

The sizes i would be using would be 3/4" and 1/4". Any knowladge would be helpfull.

Thanks

NH

[psycix]

Officially: no.
But you could. They are semi-compatible. Some sizes have the same pitch and work better together then others. Main difference is the shape of the threads.
Crossing them over does not guarantee a leak-free joint. It may also differ per manufacturer.

Here is a link with some nice information:
http://www.colder.com/Portals/0/pdfs/NPT.pdf

[jonnyboy]

I would say if your dealing with pvc and Teflon tape it COULD work. But if your dealing with metal I would say it's a no go.

[Biopyro]

What are you threading together. If you haven't (or even have) already bought it, we might be able to suggest an alternative.

[Night Hawk]

I found my alternative, the page before in the catologue was stuck to this page and has all the bspp fittings

Thanks though!

[Ragnarok]

Theoretically, you can buy converting fittings for the threads if you want to be really sure.
Airlines do them up to 1/2" size here, you might be able to find 3/4" somewhere else.

NPT male/BSPT male
NPT male/BSPP female
BSP male/NPT female

Then again, I've run sizes that really aren't supposed to be mixed before. A common one is mixing 1/2" BSPP and 15mm compression threads - with healthy amounts of PTFE tape.

[Night Hawk]

Cheers but yeah i found all bsp threads on the previous page i feel so silly.

[far_cry]

possibly you will be with leak problem