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npt versus bsp threads

npt versus bsp threads

why NPT threads are preferred over bsp threads for high pressure applications?

RE: npt versus bsp threads

I'd say the opposite is true.

BSPP with some kind of face seal is pretty popular for serious hydraulic systems. Look at automotive brakes. 1000 Plus psi. Not a tapered pipe thread to be seen.

NPT or any tapered pipe system with teflon tape or "dope" is less reliable and more difficult to assemble reliably.

RE: npt versus bsp threads

NPT is easy to create = inexpensive


RE: npt versus bsp threads

and NPT with taper and truncation will always have a leak path.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: npt versus bsp threads

In the world of pressure piping connections, the only thing I hate more than taper thread sealing concepts is finding another sealing concept (e.g. flare) that some cretin has attempted to seal with thread sealant or teflon tape. curse

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: npt versus bsp threads

In my case pressure is 306 kg/square cm.

RE: npt versus bsp threads

I have seen farm equipment designed to run at 4500psi.
Aircraft hydraulics run at 5000psi.
There are plenty of good solutions out there, don't use NPT.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: npt versus bsp threads

Pipe threads are a miserable method for making leak-free, reliable connections in high-pressure fluid systems.

RE: npt versus bsp threads

If you are stuck with a tapered pipe thread in a high pressure application, Loctite is a good solution - and I mean a thread locker - not necessarily the "hydraulic sealant" product.

je suis charlie

RE: npt versus bsp threads

I use many NPT in subsea operations with pressure around 3000 psi. Put a lot of SWAK pipe thread sealant.
It's easier because has no o-ring/seal needed. the problem arise if the thread is spoil but very less chance.


RE: npt versus bsp threads

NPT gets a bad rap because people use it in inappropriate applications, don't know what thread sealants to use, and don't know how to make up the joints properly. A hammer is a very poor screwdriver!

NPT is not an appropriate technique for high pressure applications that are also high temperature. We use NPT very sparingly above 175 C when anaerobic pipethread sealants turn into a pumpkin, and VERY sparingly above 232 C (450 F) which is the maximum service temperature for teflon tape. The best thread sealant above 232 C is liquid metal applied by a welder- all else is risky and appropriate only for very closely controlled conditions. Thread sealants like grafoil tape and X-Pando are last resort tools rather than something to rely on to keep people from being exposed to hazardous materials that might leak out of the joint.

High pressure cold connections that are not highly cyclic are perfectly fine-at sizes 1/2 NPT and below- all the way up to 6000# fitting class, if you know what you're doing and use the right sealant system. Add thermal, pressure or vibrational cycling and you'd be better off with something else.

At 150# class and temperatures below 175 C, I use NPT threads up to and including 2" without hesitation- unless the piping is designed such that a leaking joint cannot be tightened without the use of a saw, or the fluid is VERY hazardous.

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