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The world of pipe fittings

naich.net

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Re: The world of pipe fittings

#4
Conveniently, of course, the US and Canada use NPT instead of BSP, the worldwide standard. Even if an NPT fitting and a BSP fitting are the same size, one won't screw into the other, since the threads have different shapes and are at different angles.

Re: The world of pipe fittings

#6
I had a major plumbing problem some time ago (leak in the house’s main line) and paid a plumber way too much to dig a hole and fix it. I of course wasn’t about to pay him to fill the hole back up, and while it was open I took a good look. That’s when I discovered PEX. PEX is wonderful: easy to work with, inexpensive, simple to fix if you screw something up. I wish all plumbing was PEX.

I briefly installed an NPT flow meter (that was probably actually BSP) in the line. I can confirm that the PEX-to-NPT fittings leaked until I used a whole roll of PTFE tape and a mountain gorilla. Eventually the cheap flow meter started leaking from the casing itself so I ripped it out and replaced it with beautiful PEX.

Re: The world of pipe fittings

#8
"When buying male fittings, it’s best to always get tapered ones so they fit in either."

I tried that with a shop compressed air system and got lot of leaks, hissing, and the compressor turning on frequently. And I never did get the system not to hiss somewhere, so I can sympathize and ditto this rant. Even when using matching fittings, with gobs of tape and/or dope, and enough force to destroy multiple fittings, it leaks. I'd pay a plumber well to teach me some of those mystic arts, if I could find one in my plumber-free rural area.

Re: The world of pipe fittings

#9
In case anyone from the US reads this, BSPP and BSPT fittings are rare and incredibly frustrating here, as our NPT (National Pipe Taper) threads are different and the selection of BSP(P/T) fittings is extremely poor in comparison.

Also, I work with NPT fittings quite a lot:

> For what it’s worth, I tightly wrap the tape 10 times round the male thread and get an enraged mountain gorilla to tighten it up.

This is a WTF NO!!! for NPT and I’ll assume a WTF NO!!! for BSPT as well. You need about 1.5 wraps of PTFE tape to seal a fitting. Any more is wasteful and asking for leaks (or damage, if you’re using plastic fittings). It helps if you use the correct tape width for the fittings (1/4”, 1/2”, and 1” for me) and develop a wrapping method that keeps the tape under tension at all time and in such a direction that threading it into the fitting doesn’t unwrap the tape.

Also, in my experience, when someone inexperienced first learns what pipe tape is, they try to apply it to everything. 20 wraps around a tapered pipe? Wrap a Swagelok fitting? Try to make a butt joint or an adapter for two pieces of plastic tubing? I’ve seen it all.

Re: The world of pipe fittings

#10

I had a major plumbing problem some time ago (leak in the house’s main line) and paid a plumber way too much to dig a hole and fix it. I of course wasn’t about to pay him to fill the hole back up, and while it was open I took a good look. That’s when I discovered PEX. PEX is wonderful: easy to work with, inexpensive, simple to fix if you screw something up. I wish all plumbing was PEX. I briefly installed an NPT flow…

Can confirm - also started using PEX recently, and it is fantastic - wouldn't go back for anything! Straightforward, solid, more resistant to freezing (tho I still drain/blow out the outside lines in winter). I've even had zero problems with the PEX-copper fittings; I generally just attach straight onto a cut pipe rather than an NPT fitting, so that may account for my different experience.

I've run a few new lines in the house, and also new hose faucets outside. Looking at using it for both vacuum and compressed air lines in the shop.

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