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.
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.
Ahh, young padawan, the way of the elder is to buy a roll every time you have a project to do until you have achieved saturation...where there is a lightly used roll of teflon tape in every drawer and on every surface of your workshop and garage.
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.
For a REALLY good primer on the subject, read Carrol Smith’s _Nuts, Bolts, Fasteners and Plumbing Handbook_ (aka Screw to Win).
No, the tape absolutely contributes to the seal. Sure, the lubrication lets you thread more tightly without binding, but that's not to say the tape isn't contributing to the seal. If it didn't, you would still have a spiral leakage path. PTFE tape is soft enough that it deforms and prevents the spiral leakage path which can occur with any tapered threaded joint.
I've actually used PTFE tape in super high pressure situations (>1000 psi) with straight (un-tapered) joints (you aren't typically supposed to, but this was for an experiment), and it indeed sealed.
> The tape also works as a deformable filler and thread lubricant, helping to seal the joint without hardening or making it more difficult to tighten
+1 for anything by Carrol Smith
Back in my gearhead days Engineer To Win was a near constant fixture next to the toilet.
> 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.
Again, not a pipe fitter but this just screams "WRONG". If someone needs to use that much force to tighten it up, one can only assume that the pipe is now so full of tape it simply doesn't fit?
My roommate had a "unlimited BTU" gas fitter license (Canada Class "A") and this for a living and preferred "pipe dope"
"Pipe dope is generally stronger seal than Teflon tape, which is why plumbers and other professionals use it rather than tape for seals that are permanent."
I do this kind of thing a lot as we own and maintain our own water plant. My preferred sealant is the yellow PTFE tape that is used for natural gas.
It is quite a bit thicker than the white tape, it sticks to threads better and it is easier to work with, in terms of manual dexterity.
I never use the white tape for anything.
I don't like pipe dope at all and I only use it for large fittings that are going to be buried or inaccessible.
ALSO, helpful hint: If you are mixing plastic pipe (like schedule 40/80) and metal pipe, always have metal female couplings and plastic male couplings. A metal male going into a plastic female is one tighten away from cracking the plastic.
They use it because it's faster. As long as it's good enough any performance difference is secondary.
They probably use neither 10 full wraps, nor an enraged mountain gorilla, but then I’ve seen stranger things in plumbing.
At least one of them is vegetarian?
That’s me. Whoops.
Its not that the Teflon reacts with hyd oil, its that the inevitably little tiny bits of stuff physically jam/ruin seals and clog nozzles.
I’m pretty sure the author was exaggerating, because no sane person would use an enraged gorilla to tighten fittings. Gorillas are simply far too dangerous to be trusted with important plumbing work.
The standard advice I've been given when it comes to either vacuum or cryo fittings is "cut anything American off it as soon as it arrives and put DIN standard or KF kit on as soon as possible". Standards are a pain and that xkcd about there being too many of them is very, very true.
Everyone with dirty fingernails knows that 3-4 wraps is a pretty good rule of thumb for fittings that are meant to go together and you need more when you're mix and matching BSP and NPT threads because you have a larger leak path to take up.
Nobody bothers stocking multiple widths of tape. That only makes sense in a production environment where you're only ever working with one size and can build to it.
In a pinch you can "augment" things like compression fittings with tape on the OD of the ferrule.
Not a pipe fitter, but I've done a lot of plumbing on a huge variety of systems (sinks, drains, air lines, HPLCs and other chemistry equipment, bioreactors, RO systems, potato cannons). I have found through experience that the thick PTFE tape (usually grey or yellow) is almost always superior to the thin tape. I use 2-3 wraps of that and that seems to be ideal.
Thick tape is also a lot easier to remove than the thin PTFE if you have to reinstall (you aren't supposed to re-use tape if you unscrew it).
Generally BSP male fittings are always tapped which is why they don't mention it.
I just removed some from a medical oxygen DISS fitting, which is a conical seat on the inside meaning the threads do 0 sealing duh-oh.
Plumbing is hard because it is not forgiving. It's as binary as IT except you can learn the outcome with some delay, once you learnt about a damage caused by a leak. Either you do a pressure tests right or repair can be expensive. And bugfixing is always tricky.
Water also goes down whether you like it or not. Think about all possible leaks inside the shower cabin. Or what is even more impressive that under a pressure the water goes everywhere possible.
Plumbing is similar to electrical engineering, except it usually doesn't kill immidiately (though working with gas is tricky anyway) but requires similar strict mental model to do right.
And when you see a plumber it seems like this person is just a physical worker. So work status misconception must be leveled with money...
The next day at work we had to find a broken heat wire in a tiled bathroom floor, running 1000 volts through the wires to try to fuse the broken wire, then heating the floor up and searching with heat-sensitive paper overlays for the likely broken spot, then breaking the tile with a hammer and digging the wire out of the mortar bed. After we found it I thought, "I'd rather hunt software bugs".
We had some come and install an instant water heater and they cut an ugly hole in the side of the house without much thought.
At one office I worked in they called Roto-Rooter (a non-union franchise that is likely to wreck your pipes and require a call to the union plumbers afterwards) who claimed that we'd flushed a condom down the drain (very hard to believe) and wrecked the pipes so we had to call the union plumber.
Another time the sink wasn't running so we called the union plumbers, they unscrewed the aerator from the faucet, saw some crud come out and the water run and left in triumph, sure of their ability to outthink a group of mere computer nerds.
Us computer nerds were sitting at the faucet immediately after that, running it and talking about it. The now aerator free faucet clogged up again within 2 minutes of the plumbers leaving.
Considering the quality of many expensive website and software implementations I've been required to use throughout the years at various jobs, this problem is not unique to plumbers.
Hehe - now you can feel like an IT customer. I think most people feel the same about IT but the domain is just more wide and prone to excuses.
I'm guessing that is a reference to Omid Djalili sketches about Polish plumbers:
* https://www.youtube.com/watch?v=K85ZtXnMxbM
* https://www.youtube.com/watch?v=P8mjzu0Runo&t=1m
Yup, it either leaks or it doesn't.
IOW in the case of helium leak testing, it either leaks an unacceptable amount or it leaks an acceptable amount.
For higher pressures or stronger vacuums there's always this:
https://products.swagelok.com/en/all-products/fittings/c/100?
https://products.swagelok.com/en/all-products/valves/c/200?
For things like aerospace or energy.
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 a lot of work. I can't imagine putting it together as well, especially for 40 hours a week.
I agree with the author's dismay about threaded fittings, but 100% disagree about PTFE tape versus thread sealant. PTFE tape is garbage. If you use thread sealer the way it's supposed to be used (put on a decent amount, then thread the pieces together with the "nudge and a grunt" technique instead of cranking down on it with a huge amount of force), it will seal perfectly almost every time, and any minor leaks can usually be fixed by tightening the joint slightly. If that's not enough, just take it apart and redo it. I've rarely had to try twice, and never three times.
Not sure about British threaded pipe, but NPT threaded pipe actually doesn't benefit from being tightened beyond a certain point because of the way the threads are designed. I redid the seals and some of the fittings[1] on all the antique hot water radiators in a house because no contractor within a day's travel would work on antique hydronic heating systems. Good quality thread sealant, no garbagey PTFE tape, no leaks, even in constant use.
That having been said, modern pipes and fittings make things dead simple. PVC (or ABS, but PVC is nicer IMO) for drains, push-to-connect fittings for water lines (I like PEX, but I know opinions vary). No lead, no torches. Easy to cut with hand tools. Lightweight. Anyone who's interested can probably do at least basic work with modern pipes.
This is pretty interesting, because plumbers are called 'lead-pourers' (loodgieters) in Dutch, and I had always wondered why.
Same origin in English as well! (Plumbum = Lead)
https://www.wavin.com/en-en/news-cases/news/the-roman-empire...
To seal a NPT-threaded joint, use pipe dope (it's both a lubricant and a sealant).
What’s not to like about PEX?
I'm about to use PEX for the first time on my hydronic heating system, which is only ~20psi and limited volume (autofill valves are an anti-pattern). Maybe I'll fall in love, who knows.
On steel pipes and fittings obviously. Plastic ones might crack.
Also hemp fiber requires bit more practice and leverage but it's really good.
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.
What I find very useful is from a pro plumber: https://www.henkel-adhesives.com/us/en/product/thread-sealan...
Can be used for water & gas, withstands high temperature. Easy & fast to work with. Don't have to apply any additional grease for reducing friction.
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.
Amusingly he told me one of the plumbers he did get a bid from said something like "well all PEX does is save you time and money" like it was a bad thing lol.
You can in many cases snake it as well.
Seems like there's lots of situations where it's a good choice and lots of situations where it's not.
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.
The joke one is PVC + UV = shrapnel, and frankly given enough time and vibration PVC doesn't need UV to shatter, so old timers hearing you're using plastic in the shop will freak out. (edited for those who don't get the joke: Pex will definitely split or crack under UV but AFAIK never shatters, so using PVC is a major OSHA violation but using unprotected Pex is mostly safe although maybe economically unwise)
The real problem is the melting point is unimpressive and you're like one lathe chip away from an air leak. Not catastrophic but annoying. Murphy's law is air leaks only happen when you don't have time to slap a new fitting on, or when your collection of fittings is empty/missing and the store closed five minutes ago.
I've seen videos of copper pipes developing pinhole leak from corrision.
I always used aluPEX for doing the piping.
I see you’ve never had the chance to observe some of my PCB work!
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.
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.
https://waterlineproducts.com/products/push-fit-fittings-and...
There are other similar products from different companies.
Want to make money? Learn to do something people really need but not a lot of them can or want to do.
Perhaps pipe fitting is one of the "things" for plummers.
The first issue is pipes are used for a lot more than pressurized drinking water, and for compressed gases there's various standards so you don't accidentally connect your acetylene tank to your argon regulator and vice versa. Depending on local building codes, you have to work really hard in the USA to cross connect your natgas to your water supply, etc. For a home handyman this seems laughable but for giant construction projects at industrial sites you will inevitably see insane stuff sooner or later where roughed in water lines get accidentally connected to compressed air and stuff like that. I personally saw a PVC convenience pipe roughed in for ethernet cable get connected to sewer vent.
The second issue, related to the above, is NPT relies on thread deformation so the pros use pipe dope and the amateurs use teflon tape that contaminates everything, so you technically "can" use NPT for diesel or hydraulic but usually building codes and/or OSHA prevent such nonsense. Also thread deformation means every time you reuse a NPT its looser and leakier. Very slow leaking threads are not an issue for compressed air, so black iron pipe is common for industrial compressed air because who cares if 0.01% leaks out, but for flammable contamination sensitive stuff its a big issue. If 0.01% of your compressed air leaks out above a food prep assembly line nobody cares but if 0.01% of your hydraulic fluid leaks out into the food, then its a big food safety mess. The point is that most of this technology is being used outside its original use case, most NPT threads are not holding back compressed air, but crazy people are trying to use that tech to push natgas around or diesel or whatever and due to "tradition" and "codes" we are stuck with it. So the argument that NPT is shit so nobody should use it is pointless because its "really intended for" compressed air and is great for that, super cheap, easy to use, reliable enough, etc, so pointing out that its not optimal for car brakes is both true and also not useful "in practice".
Another comedy about threads: You can buy pipe dope to professionally seal NPT threads for air, natgas, car brakes, and water, but those pipe dopes are not the same, and you can cause quite a bit of trouble if you use air dope on natgas for example.
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.
The threaded fittings however are a different story. Assuming you didn't use stainless steel on stainless steel fittings [0]:
* You can find the leaks by spraying soapy water on suspect connections and looking for bubbles (wash off and dry with clean water afterwards unless you want some serious corrosion). You can also buy a jar of noncorrosive propylene glycol based leak check fluid at your local hardware store for somewhere around $10, which is a strictly better option although it's a bit harder to clean off.
* Undo the connection and throw away every fitting you can replace (you generally should not reuse NPT threaded connections unless you know what you're doing). Clean all fittings until they look brand new and with no visible debris on/in the threads.
* Watch some videos [1] and remake the connection using the proper amount of tape and sealant and appropriate torque [2]. Only tighten the fitting. If you loosen it even a bit during the process, undo it completely. Clean both sides, reapply tape and dope, and try again. Let the sealant set ~24h and retest.
[0]: Stainless steel pipe connections are a special case because they tend to cold weld before they're fully tightened. There are ways to mitigate that but the short answer is don't use them if you don't already know how.
[1]: https://www.youtube.com/watch?v=whw9ApDJpJo
[2]: NPT connections really shouldn't be torqued (you instead use turns from hand-tight for properly cut threads) but if you're having trouble find a torque chart for your fitting material (copper, brass, steel, etc) and follow that.
https://toolguyd.com/quick-guide-to-air-line-couplers-plugs/
"Hey, let me walk you through our Donnelly nut spacing and crack system rim-riding grip configuration. Using a field of half-C sprats, and brass-fitted nickel slits, our bracketed caps and splay-flexed brace columns vent dampers to dampening hatch depths of one-half meter from the damper crown to the spurve plinths. How? Well, we bolster twelve husked nuts to each girdle-jerry. While flex tandems press a task apparatus of ten vertically composited patch-hamplers. Then, pin flam-fastened pan traps at both maiden-apexes of the jim-joist."
Interesting read about the pipe fittings too though!
⸻
1. In my experience, I suppose, one could perhaps add concrete/masonry and may be something with dirt?
Regarding the threads on common pipe fittings here in Cali: NPT threads are designed to be cut with a pitch and angle that are self sealing.
Sealing compounds can assist in the lubrication of threads to easily tighten them up but should not be absolutely necessary.
Imo it's an aid to assembly and disassembly and not always necessary depending upon the application. And in some applications it's forbidden
I see the author used the word "spanner" so I assume they're British which is why they have to earnestly deal with BSP. For fellow Americans, don't get anything BSP/BSPP/BSPT unless you have to (eg hydraulics commonly use BSPP/G-thread, and the bonded rubber washer is not optional).
For pipe tape/dope, the important thing to know is their main purpose is to reduce friction so you can tighten a joint further, which deforms the threads more - packing the threads is a secondary effect. I generally do dope, then 2-3 wraps of tape (in the right direction, of course), then dope again. I generally use the thicker blue tape, but thinner white should be the same with a few more wraps. I learned this trick from an old timer at a hardware store, and it has definitely helped on some recalcitrant joints. I'd rather not find leaks after something is assembled, so I just take the time and do it on most every joint now. (For reference, I mostly deal with 1/4 - 1 inch NPT brass/stainless/copper threads).
Also, not every type of connection takes dope/tape! For example, while US showers generally have NPT-M coming out of the wall, the showerhead generally has a rubber washer that makes the seal, and thus does not need tape. Similarly with flare/compression fittings.
Also, plumbers get paid a lot because it's generally heavily regulated - water supply contamination is one of those things we've refined over centuries and now take for granted. The regulation means they get a middle class wage, which is prohibitively expensive for other individuals to pay owing to high taxes and other overhead. Imagine how much it would cost to hire yourself as a software engineer for half a day.
NPT has some flaws and complexities but generally while it’s comprehensive conventions and practices mean that for specific types of plumbing you’ll need some specific standard fittings and once you get used to them that’s pretty much that. From gases to liquids. None of this “whoa someone decided to use a tapered one here” you don’t get to chose what fitting you’re feeling like that day, we have building codes and if it’s a pipe in a wall carrying water than there’s a convention (and likely building code) that tells you your pipe, fitting, and which way the threads should turn! (Generally in the broadest strokes: Explosive gases are reverse threaded. Everything else isn’t.)
Anyway we’ve been saying no to bad British ideas since 1776. Don’t blame us outside the Americas the rest of you (and ISO) fell for it.
https://en.m.wikipedia.org/wiki/Compression_fitting
Working in labs on fluid and vacuum lines (<1in diameter) this is the way.
If only it wouldn’t cost as much as the house in fittings + tube to hardpipe stainless fittings on our water supply lines.
I stayed in a hostel hotel in Munich, DE with hard piped bathroom water lines. I was impressed and think they must have been in service for 30-50 years.
The error that will destroy your pipes is to use anything copper in the condensate plumbing of a condensing boiler. Use PVC, CPVC or PEX (or stainless steel) with plastic fittings (PVC, CPVC, “engineered polymer”, or John Guest ProLock or similar). The high CO2 concentrations in the condensate will rapidly corrode copper.
Thanks to all the good people on Hacker News for their input, from which I've learned a lot. I should stress that any following advice is not from a professional plumber and is purely from my own experience as an idiot making a low pressure beer handling system. It should not be read as the proper way to do anything, especially if you are working on pressurised systems and definitely totally 100% not with gas fittings. Get someone in to do that, you lunatic. Seriously. Don't mess with gas.
For drains, pvc of course.
Given run-of-the-mill refurbby waterline junk with plain ol copper, I like that brass kind of compression with the little sleeve.
Don't trust sharkbite. Am a mediocre sweater.
For gas, threaded with that pipe goo works surprisingly well. Haven't fucked it up yet.
I wonder if you can use pex with gas
* You both design and then build a thing.
* No one else knows how it works or cares until it stops working.
* Through work you build up your own set tools and methods that you like and can apply to various jobs.
Seeing that American can't even adopt the metric system, I have little hope for a clear international standard for pipe fittings.
For when you want to have a pipe-to-pipe adapter to hang a radio on a tower, or wall mount it on top of a building mechanical penthouse or similar.
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.
Getting a good seal on a sink drain can be a little tricky the first time too.
How the US military, nuclear power plants, and plumbers worth their weight in salt do fittings: 3-4 times around the (male) fitting with PTFE tape, then a light amount of pipe dope on top of the PTFE tape.
Also, DO NOT buy the cheap PTFE tape as suggest. Buy the milspec tape. Your big box store will have both and you'll know where that money (a couple dollars at most) went.
There is a high-density thread sealing PTFE tape that works a bit better than the el' cheapo generic white stuff (although it's usually white too). Anything marked as such should be sufficient unless you are working on an oil rig or nuclear reactor.
EDIT: Unless the package has MIL-T-27730 on the tape, labeling it milspec has no meaning.
It means a product meets stringent requirements that can't be cheated on.
Yes, MilSpec [0].
>Doesn't that normally equal as cheap as they can get away with?
No, wrong. You're thinking of "military grade", which is effectively meaningless as a term.
>There is a high-density thread sealing PTFE tape that works a bit better than the el' cheapo generic white stuff
This is what I was alluding to. It's thicker and denser.
>EDIT: Unless the package has MIL-T-27730 on the tape, labeling it milspec has no meaning.
This is where you're wrong. Milspec has a specific meaning [0]. The milspec in question is Military Spec # A-A-58092 [1].
[0] https://en.m.wikipedia.org/wiki/United_States_Military_Stand...
[1] https://www.lowes.com/pd/Oatey-0-6-in-x-43-ft-Plumber-s-Tape...
That doesn't sound like a good idea at all. The whole idea behind PTFE (aka Teflon) is that it reduces friction because nothing, including pipe dope, sticks to it. What value does the pipe dope add to a properly-wrapped fitting?
"imagine putting a tapered male in a straight female"
