1/8" NPT tap used :) for 1/8" BSPT male

steptoe · Post by **steptoe** » Fri Dec 20, 2013 11:12 am

Just thought worth a mention in case anyone gets to this point and wonders.....

I have a 1/8" NPT tap rated at 27 threads per inch, have a brass fitting of 1/8" BSPT rated at 28 thread per inch - herumph

! So a google found a forum where a guy in Melbourne said his performance workshop did it all the time and worked well , on exhaust temp probe bungs anyway.

Others also said it worked OK, or vice versa - and use some sort of gasket goo. Some were using this conversion method for oil pressure lines and fittings.
I just needed it for a water fitting in an alloy manifold. Screwed in once for a test fit, undo it and refit with some threebond - now it will never leak coolant with that impervious stuff !

T is for taper thread

RSR 555 · Post by **RSR 555** » Mon Dec 30, 2013 2:09 pm

I thought T stood for Thread?

NPT = National Pipe Thread (USA)
BSPT = British Standard Pipe Thread (UK)

From memory all pipe threads are tapered for sealing purposes

Gannon · Post by **Gannon** » Mon Dec 30, 2013 2:14 pm

Yeah I vote 1 for T = tapered

I used a NPT oil pressure gauge in my Kubota which has a BSPT thread in the block to test oil pressure. Am now using a Subaru oil pressure switch

In my googleing I found that NPT is close enough to BSPT to seal with thread tape. BSPT male in BSPT female shouldnt need tape cos the taper makes it water/oil/air tight

RSR 555 · Post by **RSR 555** » Mon Dec 30, 2013 2:59 pm

Gannon wrote:Yeah I vote 1 for T = tapered

I used a NPT oil pressure gauge in my Kubota which has a BSPT thread in the block to test oil pressure. Am now using a Subaru oil pressure switch

In my googleing I found that NPT is close enough to BSPT to seal with thread tape. BSPT male in BSPT female shouldnt need tape cos the taper makes it water/oil/air tight

With your googleing, you should have found this too...
https://www.ralstoninst.com/news/story/ ... spt-seals/

Gannon · Post by **Gannon** » Mon Dec 30, 2013 6:12 pm

Well there ya go. I'll bookmark that page.

steptoe · Post by **steptoe** » Mon Dec 30, 2013 7:49 pm

hmmm BSPT-T then ?

little bit of data to correct in brain .....