Pipe Thread Sizes

[stubuzz]

There have been many discussions about pipe thread sizes in this forum, but there has never been a definitive answer to whether they are NPT or BSP.

 

I found an interesting link from the Thai Pipe Industry  that states that male threads are tapered and female are straight. However it does not state if they follow the British or American system, so I have emailed SCG and the Thai pipe Industry to get an answer.

 

Thai Pipe Insustry- https://www.thaipipe.co.th/product-02-01-eng.html

 

Link to thread sizes- https://www.thaipipe.co.th/demos/product/content-02/01/01/pic-b/02.pdf

 

Here is a good explanation of the threads. https://www.valvesonline.com.au/references/threads/

 

Thread Taps on Lazada-https://www.lazada.co.th/products/g18-14-38-12-34-hss-taper-pipe-tap-bsp-metal-screw-thread-cutting-tools-i2970833789-s10899819948.html?

 

 

Edited December 4, 2021 by stubuzz

[VocalNeal]

1 hour ago, stubuzz said:

so I have emailed SCG and the Thai pipe Industry to get an answer.

I don't really see the point? If you buy stuff here it will all fit. Only if you buy stuff from abroad, in either case, will it make any difference? Unless you try and mix and match. OK BSP is 55 deg. and NPT is 60 deg.

If stranded on a desert island and unsure you'd be OK above 1/2in if you had some thread tape and very large adjustable. 

 

Based on the info from Thai pipe you provided the answer is BSP.

 

 

Edited December 4, 2021 by VocalNeal

[sometimewoodworker]

4 hours ago, stubuzz said:

I found an interesting link from the Thai Pipe Industry  that states that male threads are tapered and female are straight.

That is far from universally true. I have male threads that are definitely not tapered. In point of fact none of the male threads I have that I have checked are tapered. There are certainly fittings with tapered thread though I’ve never knowingly used them.

[stubuzz]

15 hours ago, sometimewoodworker said:

That is far from universally true. I have male threads that are definitely not tapered. In point of fact none of the male threads I have that I have checked are tapered. There are certainly fittings with tapered thread though I’ve never knowingly used them.

I am surprised that there aren't water leaks in every house. I changed 2 taps yesterday and no mater how much PTFE tape I used there was a very small drip. I then spent a couple of hours scouring the town for Permatex thread sealant which sorted the problem instantly. 

[Bill97]

27 minutes ago, stubuzz said:

I am surprised that there aren't water leaks in every house. I changed 2 taps yesterday and no mater how much PTFE tape I used there was a very small drip. I then spent a couple of hours scouring the town for Permatex thread sealant which sorted the problem instantly. 

Tap connected to flex hose like most of them?  Seal is with a rubber washer in flex head. No tape needed.

 

Also very small drips usually stop within 24 hours of new installation.

 

[shaemus]

The threads used in Thailand are predominantly BSSP with some male items being BSST. 

 

Quite acceptable to use tapered into parallel. 

 

I use a combination of ptfe tape and thread sealant paste for my outdoor / pump thread. I was chatting to some pipe fitters at work and that is what was in the spec for their work (bhp) so I decided to copy it. 

 

Shaemus