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.
"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.
As someone who is NOT a pipe fitter but lived with one for many years.. It was odd reading this and I'm glad someone like you responded to correct things.
> 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."
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!)
The real pro-tip is not to use tape at all. Instead use pipe dope or joint compound, it's cheap, easy, and better in every possible way. If you only have two do one or two very low importance joints, like a showerhead then tape is fine. But for anything serious use the joint compound. If you are doing a lot of work it's absolutely a game changer.
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.
In Germany using hemp fibers instead of the PTFE tape is still really common (together with a sealing paste calle Neo-Fermit). The disadvantage of the tape is that you can't turn the fitting backwards even a little bit when tightening it, or you get leaks. With hemp that does not matter so much as it swells up with water.
I particularly hate the confusion that BSP and NPT cause. They're almost interchangeable (differing, iirc, probably on the angle of flank) and will get about three turns in and then leak or fail under pressure. In my world, this has led to graduate students spraying liquid nitrogen around. It's clearly the case that the two probably were supposed to be identical but diverted due to manufacturing differences in the distant past.
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.
Your comment reeks to high heaven of textbook engineer. The practices you advise do not survive in a world of bottom dollar commodity pipe fittings.
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.
> You need about 1.5 wraps of PTFE tape to seal a fitting.
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).
If you want a really good seal you wrap the tape 1-2 overlaps at the start of the thread and progressively make it thicker and thicker so you have more overlaps (10x) at the base. I guess it depends on the fittings but some run out of tapper and you can't tighten it anymore without the hexagonal nut hitting the adjacent fitting. This works well as you're building your own tapper which is sort of acting as an o-ring.
Generally BSP male fittings are always tapped which is why they don't mention it.
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.
This article doesn't touch much about why plumbing is hard. I'm from Poland so I'm not only IT but also a plumber ;)
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...
I had a funny experience a week ago. One night working on a hobby web project it took me three or four hours to debug something, I finally got to bed around midnight thinking "boy, programming is hard".
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".
My complaint is that plumbers frequently do poor work for the money.
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.
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 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.
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.
Teflon tape is a lubricant, it's not meant to seal the joints. So for example if you're screwing a shower head "hockey stick" pipe into a drop ear elbow in the wall, and it stops at a weird angle instead of pointing down -- use PTFE tape on the threads to make them slide against the ones in the fitting more easily, it'll turn further.
To seal a NPT-threaded joint, use pipe dope (it's both a lubricant and a sealant).
Also, I should mention that I've used PTFE tape without any issues for air tool connections. It's just for plumbing - where even a slow, tiny leak can cause massive damage - where I think it's a terrible choice.
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.
Came here to also plug PEX. A friend used it for his remodel, did most of the work himself, and set everything up so all the lines come down to a sort of "switchboard" panel in his basement, so that as he did more remodeling work in the future he could disconnect individual loops trivially. It just makes so much sense and is so easy vs copper pipe.
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.
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.
I've not done any major replumbing yet but I've been watching Matt Risinger [1] on YouTube for a few months and have quickly become a PEX fanboi. He's a home builder based in Texas and uses PEX for basically every job. There are some videos on his channel comparing different types of PEX and PEX against other systems.
We started with welded joints, then moved to threaded (and every variation in between of that). I kind of wonder if PEX will be deprecated some day by something even better. We are going to end up with yet another standard that PEX has to interface with. Feels like an xkcd... https://xkcd.com/927/
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.
I'm really not confident about copper pipes. Metals in solder are very different electrochemically than copper. There might be other electrically connected metals in the installation. There might be some impurities grains in the copper.
I've seen videos of copper pipes developing pinhole leak from corrision.
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.
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.
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.
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.
There are a few pipe dopes that advertise a wide range of material comparability. I recently purchased some for a automotive racing fuel pump setup that was rated for gasoline, nat gas and water.
"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.
If you're talking about quick connects, they'll always leak a bit.
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.
[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.
I had to do some plumbing work a few years ago and quite enjoyed solving the puzzle and completing the work myself. It did remind me a lot of my day job in tech. No individual part of the job is all that difficult but planning and executing everything properly, and all the cryptic/arcane knowledge required, was very similar. And just like when one of my networks or systems is down the work had to be completed quickly to resolve the outage.
"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."
Of the three aspects of home maintenance that are most common¹: plumbing, electrical and carpentry, I feel most comfortable with plumbing. It seems nicely discrete in that you’re generally putting together existing components without having to do much if any measuring and cutting. That said, I’m moving into a new house where I’ve got a handful of carpentry projects that will definitely stretch my abilities in that arena.
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1. In my experience, I suppose, one could perhaps add concrete/masonry and may be something with dirt?
There are plenty of technical comments here, but I have to say I got a great laugh from this post. I have dealt with many of the absurdities state side, so I can relate to your experience. By the time I got to the words Windows XP Screensaver, I was laughing so hard I couldn't read anymore. After finishing, I bookmarked you. Looking forward to more. Thanks.
Cheap fittings from GENSYM sellers on Amazon/Ebay/Aliexpress will have crappy threads, which will cause you endless pain. I'm guessing this is what inspired the author's rant. I generally try to buy fittings from suppliers that have an incentive to do some quality control. If one thread in a joint isn't perfect you're probably fine, but when both are terribly out of spec, it will never seal.
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.
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.
This guy wrote a whole article outlining how bad and unusable the British pipe standards are and you’re surprised the two (ish) continents that don’t use them are actually pretty happy with their standard and don’t want the other?
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.
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.
They're paid so much because you need to pay twice for the bad ones. My house's previous plumber threaded a copper line directly into the stainless steel DHW tank. That wasn't a problem, until it was.
I’ve never encountered a DHW tank made of stainless steel with stainless steel fittings.
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.
Exactly, I do the simple stuff myself and only call a plumber when it involves crawling around in a spider infested crawl space, working with poop, or similar things I am willing to oay someone to do.
In one of the larger companies in Sweden in the third largest city Malmö that sell to both other companies and consumers none of the staff knew what I was talking about when I mentioned that BSP and NPT are different. Neither people on the floor nor people answering the phone. These were what appeared to be experienced plumbers. It’s amazing.
I had to learn the arcane world of pipe fitting sizes working with pneumatics for a scuba equipment project. It is extremely confusing. Unfortunately, it can have fatal consequences. In a recent story, a scuba store employee used the wrong size fitting on a 3,000 psi scuba tank which shot out and killed them.
Seeing that American can't even adopt the metric system, I have little hope for a clear international standard for pipe fittings.
All Americans completely understand the metric system. We can convert anything to anything in our heads. By the way, we all speak a dozen foreign languages fluently, just choose not to. It is because we are so humble that you do not know this.
Of other industrial interest re: pipes, sch40 and sch80 hot dip galvanized pipes in various outer diameters are also a standard item for telecom construction projects.
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.
One thing I’ve learned the hard way is that you need those little gasket seals on the inside to avoid a leak but if you over tighten the connection with a gasket inside you can actually get a leak just from over tightening it!
When I had to do some plumbing I found that everything was undocumented. One source would tell you to refer to the documentation published by the manufacturer of the fitting, which is of course impossible to find.
I had a doctor once who was quitting his solo practice and taking a regular job at a hospital, having become disillusioned with the biz. He said his house was bought by a plumber, who was trading up.
This article sucks. Lots of bad info from an inexperienced plumber.
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.
Milspec, lol. Doesn't that normally equal as cheap as they can get away with?
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.
3-4 times around the (male) fitting with PTFE tape, then a light amount of pipe dope on top of the PTFE 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?
Mate, I'm not a plumber and it's 100% written from the perspective of someone who is not a plumber. This article is not an instruction manual for plumbers, but a blog of what a non-plumber found to work for him.
jkqwzsoo|3 years ago
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.
hilbert42|3 years ago
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.
mgarfias|3 years ago
For a REALLY good primer on the subject, read Carrol Smith’s _Nuts, Bolts, Fasteners and Plumbing Handbook_ (aka Screw to Win).
kennend3|3 years ago
> 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."
aidos|3 years ago
They probably use neither 10 full wraps, nor an enraged mountain gorilla, but then I’ve seen stranger things in plumbing.
mannykannot|3 years ago
balls187|3 years ago
That’s me. Whoops.
hattmall|3 years ago
bdowling|3 years ago
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.
robk|3 years ago
shellfishgene|3 years ago
azalemeth|3 years ago
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.
dsfyu404ed|3 years ago
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.
kortex|3 years ago
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).
berjin|3 years ago
Generally BSP male fittings are always tapped which is why they don't mention it.
TheJoeMan|3 years ago
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.
unknown|3 years ago
[deleted]
sokoloff|3 years ago
PaulDavisThe1st|3 years ago
agsamek|3 years ago
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...
georgeoliver|3 years ago
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".
PaulHoule|3 years ago
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.
throw0101c|3 years ago
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
* https://www.youtube.com/watch?v=_FM9Ps6cW9U
* https://en.wikipedia.org/wiki/Omid_Djalili
fuzzfactor|3 years ago
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.
iancmceachern|3 years ago
blincoln|3 years ago
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.
[1] https://youtube.com/watch?v=MeHiE-j1KuQ
Tijdreiziger|3 years ago
This is pretty interesting, because plumbers are called 'lead-pourers' (loodgieters) in Dutch, and I had always wondered why.
blincoln|3 years ago
btbuildem|3 years ago
To seal a NPT-threaded joint, use pipe dope (it's both a lubricant and a sealant).
cmclaughlin|3 years ago
What’s not to like about PEX?
blincoln|3 years ago
TEP_Kim_Il_Sung|3 years ago
baybal2|3 years ago
[deleted]
thedanbob|3 years ago
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.
jasonwatkinspdx|3 years ago
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.
toss1|3 years ago
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.
ssl232|3 years ago
[1] https://www.youtube.com/@buildshow
bilsbie|3 years ago
unknown|3 years ago
[deleted]
ropable|3 years ago
iancmceachern|3 years ago
latchkey|3 years ago
Kaibeezy|3 years ago
scotty79|3 years ago
I've seen videos of copper pipes developing pinhole leak from corrision.
I always used aluPEX for doing the piping.
Scoundreller|3 years ago
I see you’ve never had the chance to observe some of my PCB work!
mildchalupa|3 years ago
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|3 years ago
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.
c_o_n_v_e_x|3 years ago
digitalsushi|3 years ago
frosted-flakes|3 years ago
loeg|3 years ago
xyzelement|3 years ago
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.
VLM|3 years ago
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.
mildchalupa|3 years ago
hirundo|3 years ago
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.
katmannthree|3 years ago
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.
loeg|3 years ago
https://toolguyd.com/quick-guide-to-air-line-couplers-plugs/
jsz0|3 years ago
bmalicoat|3 years ago
https://www.lgclaret.com/
"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."
dtjohnnymonkey|3 years ago
tehwebguy|3 years ago
Interesting read about the pipe fittings too though!
dhosek|3 years ago
⸻
1. In my experience, I suppose, one could perhaps add concrete/masonry and may be something with dirt?
turdherder|3 years ago
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
naich|3 years ago
typhonic|3 years ago
mindslight|3 years ago
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.
jasonhansel|3 years ago
djcapelis|3 years ago
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.
ok_computer|3 years ago
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.
1970-01-01|3 years ago
amluto|3 years ago
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.
naich|3 years ago
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.
luxuryballs|3 years ago
iancmceachern|3 years ago
swayvil|3 years ago
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
ssl232|3 years ago
iancmceachern|3 years ago
synecdoche|3 years ago
csours|3 years ago
everyone|3 years ago
* 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.
joshuaheard|3 years ago
Seeing that American can't even adopt the metric system, I have little hope for a clear international standard for pipe fittings.
noNothing|3 years ago
walrus01|3 years ago
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.
playingalong|3 years ago
lelandfe|3 years ago
OJFord|3 years ago
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.
mongol|3 years ago
digitalsushi|3 years ago
midhhhthrow|3 years ago
PaulHoule|3 years ago
AlbertCory|3 years ago
weare138|3 years ago
victor9000|3 years ago
zackbloom|3 years ago
fijiaarone|3 years ago
lisper|3 years ago
throwawayacc4|3 years ago
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.
Severian|3 years ago
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.
CamperBob2|3 years ago
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?
naich|3 years ago
jesusofnazarath|3 years ago
[deleted]
zabzonk|3 years ago
"imagine putting a tapered male in a straight female"