[mildchalupa]

The Teflon tape is only to be used as a friction modifier as NPT and other tapered threads seal on the threads. Reduced friction means that you can get enough load to deform the metal threads and create a seal. Be careful to not add tape to the first 2 threads as small pieces of Teflon tape can break off and get stuck into valves and things within appliances causing them to leak. There is nothing wrong with pipe dope and I find it to be superior though messy.

Annoyance for those in the states: Big box stores used to advertise fittings as NPT (National pipe thread). NPT being an ANSI spec. They seem to have switched to MIP and FIP for Male Iron Pipe and Female Iron Pipe. These are NPT as well but with a new name? Perhaps they are looking to avoid holding themselves to the spec?

Lead content in brass drinking water rated piping and fittings are being phazed out for obvious reasons. New low lead brass is stronger and does not deform as easily as the older leaded brass fittings. The result is that some fittings are now more difficult to tighten untill leak free.

Pex and crimped copper fittings are not without there own issues. Relying on an o-ring with a 30 year shelf life is problematic when the pipe is behind drywall.

Perhaps one day we will get laser welded copper fittings.

[imglorp]

> Relying on an o-ring

Another category is Shark Bite, a simple push-on tech that is almost homeowner proof. All you need for many jobs is a cutter, some sandpaper, and the fitting: no pro tools, no torch. There are tight joist spaces the new copper crimper won't fit and overhead soldering is fraught, which you can sharkbite in 2 minutes.

Back to O-rings, I do wonder about the lifetime of the seals in there though.

[cf100clunk]

If Shark Bite products are not available there is also the Waterline Push-N-Connect line of similar products for homeowners:

https://waterlineproducts.com/products/push-fit-fittings-and...

There are other similar products from different companies.

[belorn]

Depend on size and material of the o-ring. A o-ring is a flexible material that under pressure will bend in order to fit a space. Under high pressure the material might intrude out slowly, if you repeatably bend it it might snap, and as with many flexible materials it may go brittle and crack if exposed to changes in temperature or moisture.

[c_o_n_v_e_x]

In a previous life, I managed a team of instrumentation and tubing fitters at a new chemical plant that was being built. Some of the tubing for the process analyzers (chromatographs) had to be redone as they used PTFE tape on the fittings which was being detected by the GC.

[digitalsushi]

it's really easy to go crazy at a box store and get boiler fittings for a garden project. read the labels for lead content!

[frosted-flakes]

Crimped PEX fittings do not use o-rings.

[loeg]

I've seen FNPT and MNPT but not FIP/MIP.