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The world of pipe fittings

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Re: The world of pipe fittings

#31

Post by digitalsushi »

mildchalupa wrote: post #27

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…

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!

Re: The world of pipe fittings

#33

Post by [deleted] »

Tijdreiziger wrote: post #26
blincoln wrote: post #12

I've helped out with some plumbing work in an older house, and it's pretty fascinating to see the progression of technologies. 100 years ago, most drain pipes in the US were massive cast-iron pieces with no threads at all. They were mated together, then the joint was filled with a compound called oakum. To really hold it together, the plumber would pour molten lead on top of the oakum. Just taking that stuff apart is…

> To really hold it together, the plumber would pour molten lead on top of the oakum. This is pretty interesting, because plumbers are called 'lead-pourers' (loodgieters) in Dutch, and I had always wondered why.

[deleted]

Re: The world of pipe fittings

#34

Post by MomoXenosaga »

blincoln wrote: post #13
blincoln wrote: post #12

I've helped out with some plumbing work in an older house, and it's pretty fascinating to see the progression of technologies. 100 years ago, most drain pipes in the US were massive cast-iron pieces with no threads at all. They were mated together, then the joint was filled with a compound called oakum. To really hold it together, the plumber would pour molten lead on top of the oakum. Just taking that stuff apart is…

Just to be clear, I'm not trying to discount the skill and knowledge of professional plumbers. It's an incredibly complex field (especially since they need to be familiar with decades of different pipe technology), and usually involves working in filthy parts of the house no one else wants to go into. They deserve every penny.

Normally the market is supposed to correct these things but sadly we've created a culture that looks down on physical labour. Now there is a small group that can charge whatever they want.

Re: The world of pipe fittings

#35

Post by mannykannot »

jkqwzsoo wrote: post #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…

What do you think of the advice that it is acceptable to use a tapered male thread in a straight female one? My guess is that if you do that, you have at best one turn of the thread helix holding them together and providing a seal (and perhaps you would be trusting in nothing more than the tape jammed between the threads if you used ten turns of it!)

Re: The world of pipe fittings

#36

Post by imglorp »

mildchalupa wrote: post #27

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…

> 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.

Re: The world of pipe fittings

#37

Post by dotancohen »

blincoln wrote: post #21
TEP_Kim_Il_Sung wrote: post #16

Earlier quoted context omitted.

hemp fiber > PTFE tape

For sure. Those oakum + lead joints were problem-free a century after they were installed. How many of us can expect that from the things we do at work? The only reason some of that pipe needed to be replaced was that it was fused (by rust) to mid-20th-century galvanized pipe that had rusted completely shut.

Those lead joints were leaching lead into the water. If it was a supply pipe, as opposed to a drain, then people were ingesting that lead. It needed to be replaced whether it was leaking or not.

Re: The world of pipe fittings

#38

Post by sokoloff »

jkqwzsoo wrote: post #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…

I use a minimum of 4 wraps and usually 5 or 6 wraps on black pipe in the 3/4”-2” range. 2 wraps might be enough for nice clean plastic or brass threads in the 1/2” or less range, but larger steel fittings need more PTFE tape.

Re: The world of pipe fittings

#40

Post by Kaibeezy »

All this plumbing talk got me remembering the time I redid a bunch of the copper in a fixer-upper. Reading up on solder joints, I got into the underlying metallurgy, and discovered solder isn’t “glue”. You have to abrade it to remove the oxide, quickly cover the raw copper with flux, and then let the boiling flux draw the molten solder into the joint. It doesn’t take much, and you end up with a metal-metal-metal bond. Once I understood the point, the joints were a breeze. Later, I had a pro plumber in to deal with some iron pipe, noticed my copper work and was impressed. Very satisfying.
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