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The world of pipe fittings

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Re: The world of pipe fittings

#41

Post by blincoln »

dotancohen wrote: post #37
blincoln wrote: post #21

Earlier quoted context omitted.

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.

It was just the drain pipe system that was built that way (at least in the house I helped out with). All of the supply lines were galvanized steel, replaced with PEX.

Re: The world of pipe fittings

#42

Post by hilbert42 »

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…

"You need about 1.5 wraps of PTFE tape to seal a fitting. Any more is wasteful and asking for leaks"

I would have thought this obvious and it's essentially my experience (and I'm definitely not a plumber). However, I've found that more PTFE tape is needed on old or worn fittings or on ones that have damaged or badly cut threads—or when mating same sized pipes/fittings but each with different threads (yes, that's a desperate brute-force move in an emergency but I've had to force such matings on more than one occasion). In these circumstances, I'll use two or three turns or more often by trial and error—and this changes somewhat depending on whether I'm using thinner white PTFE tape or the thicker pink one.

Of course—not being plumber—it often happens that when I urgently need PTFE tape I cannot find it (it having been filed in some obscure place that I've forgotten about—even though I keep a reasonable stock of it), it's then I fall back to the good old combination of Hessian/burlap jute-type rope (of which there is always some lying around in my workshop) and linseed oil based paint. It's messy and much less convenient combination than PTFE tape but it still works wonderfully well. Moreover, it's more tolerant of the amount applied as the linseed oil actually binds to the pipe surface as opposed to the more 'mechanical' bond of the PTFE.

Re: The world of pipe fittings

#43

Post by OJFord »

playingalong wrote: post #7

What would you call this writing style (which I like a lot). Ironic? Any more specific name?

'Annoying', personally.

Seriously though, sort of a monologue? Or I'd describe it (not a single word) as spoken English taken to paper, in an oral style, or something.

Re: The world of pipe fittings

#44

Post by cmclaughlin »

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…

> I like PEX, but I know opinions vary

What’s not to like about PEX?

Re: The world of pipe fittings

#45

Post by SaintGhurka »

hilbert42 wrote: post #42
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…

"You need about 1.5 wraps of PTFE tape to seal a fitting. Any more is wasteful and asking for leaks" I would have thought this obvious and it's essentially my experience (and I'm definitely not a plumber). However, I've found that more PTFE tape is needed on old or worn fittings or on ones that have damaged or badly cut threads—or when mating same sized pipes/fittings but each with different threads (yes, that's a de…

"combination of Hessian/burlap jute-type rope (of which there is always some lying around in my workshop) and linseed oil based paint."

Could you explain that? How do you seal pipe fittings with rope?

Edit: found an explanation. TIL that you can use the fibers just like tape and wrap the threads.

Re: The world of pipe fittings

#46

Post by bathtub365 »

MomoXenosaga wrote: post #34
blincoln wrote: post #13

Earlier quoted context omitted.

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.

Is the market not supposed to reflect culture?

Re: The world of pipe fittings

#47

Post by belorn »

imglorp wrote: post #36
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.

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.

Re: The world of pipe fittings

#48

Post by rdl »

balls187 wrote: post #28
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…

> Also, in my experience, when someone inexperienced first learns what pipe tape is, they try to apply it to everything. That’s me. Whoops.

Ugh, I applied it to PVC pipe, which made it leak, sigh.

Re: The world of pipe fittings

#49

Post by radlad »

cmclaughlin wrote: post #44
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…

> I like PEX, but I know opinions vary What’s not to like about PEX?

I believe it's less durable than alternatives.

Re: The world of pipe fittings

#50

Post by [deleted] »

mannykannot wrote: post #35
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!)

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