The world of pipe fittings

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&#x2F;T) fittings is extremely poor in comparison.<p>Also, I work with NPT fittings quite a lot:<p>&gt; 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.<p>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&#x2F;4”, 1&#x2F;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.<p>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.

This article doesn&#x27;t touch much about why plumbing is hard. I&#x27;m from Poland so I&#x27;m not only IT but also a plumber ;)<p>Plumbing is hard because it is not forgiving. It&#x27;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.<p>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.<p>Plumbing is similar to electrical engineering, except it usually doesn&#x27;t kill immidiately (though working with gas is tricky anyway) but requires similar strict mental model to do right.<p>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&#x27;ve helped out with some plumbing work in an older house, and it&#x27;s pretty fascinating to see the progression of technologies.<p>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&#x27;t imagine putting it together as well, especially for 40 hours a week.<p>I agree with the author&#x27;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&#x27;s supposed to be used (put on a decent amount, then thread the pieces together with the &quot;nudge and a grunt&quot; 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&#x27;s not enough, just take it apart and redo it. I&#x27;ve rarely had to try twice, and never three times.<p>Not sure about British threaded pipe, but NPT threaded pipe actually doesn&#x27;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&#x27;s travel would work on antique hydronic heating systems. Good quality thread sealant, no garbagey PTFE tape, no leaks, even in constant use.<p>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&#x27;s interested can probably do at least basic work with modern pipes.<p>[1] <a href="https:&#x2F;&#x2F;youtube.com&#x2F;watch?v=MeHiE-j1KuQ" rel="nofollow">https:&#x2F;&#x2F;youtube.com&#x2F;watch?v=MeHiE-j1KuQ</a>

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.<p>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.

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.

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.<p>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?<p>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.<p>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.<p>Perhaps one day we will get laser welded copper fittings.

Why &quot;someone&quot; gets paid a lot was a discussion topics this Thanksgiving. The answer is as always &quot;law of supply and demand.&quot;<p>Want to make money? Learn to do something people really need but not a lot of them can or want to do.<p>Perhaps pipe fitting is one of the &quot;things&quot; for plummers.

The story misses some points.<p>The first issue is pipes are used for a lot more than pressurized drinking water, and for compressed gases there&#x27;s various standards so you don&#x27;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.<p>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 &quot;can&quot; use NPT for diesel or hydraulic but usually building codes and&#x2F;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 &quot;tradition&quot; and &quot;codes&quot; we are stuck with it. So the argument that NPT is shit so nobody should use it is pointless because its &quot;really intended for&quot; 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 &quot;in practice&quot;.<p>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.

&quot;When buying male fittings, it’s best to always get tapered ones so they fit in either.&quot;<p>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&#x2F;or dope, and enough force to destroy multiple fittings, it leaks. I&#x27;d pay a plumber well to teach me some of those mystic arts, if I could find one in my plumber-free rural area.

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&#x2F;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.

I was hoping this was going to be written by Leslie Claret.<p><a href="https:&#x2F;&#x2F;www.lgclaret.com&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.lgclaret.com&#x2F;</a><p>&quot;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.&quot;

Probably because you only call them when building or solving a water or poop related emergency, so times when you <i>really</i> need a plumber.<p>Interesting read about the pipe fittings too though!

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.<p>⸻<p>1. In my experience, I suppose, one could perhaps add concrete&#x2F;masonry and may be something with dirt?

Real life licensed and certified plumber here.<p>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.<p>Sealing compounds can assist in the lubrication of threads to easily tighten them up but should not be absolutely necessary.<p>Imo it&#x27;s an aid to assembly and disassembly and not always necessary depending upon the application. And in some applications it&#x27;s forbidden

Having just completed a small project involving plumbing, this post on my blog comes from the heart.

Cheap fittings from GENSYM sellers on Amazon&#x2F;Ebay&#x2F;Aliexpress will have crappy threads, which will cause you endless pain. I&#x27;m guessing this is what inspired the author&#x27;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&#x27;t perfect you&#x27;re probably fine, but when both are terribly out of spec, it will never seal.<p>I see the author used the word &quot;spanner&quot; so I assume they&#x27;re British which is why they have to earnestly deal with BSP. For fellow Americans, don&#x27;t get anything BSP&#x2F;BSPP&#x2F;BSPT unless you have to (eg hydraulics commonly use BSPP&#x2F;G-thread, and the bonded rubber washer is not optional).<p>For pipe tape&#x2F;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&#x27;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&#x2F;4 - 1 inch NPT brass&#x2F;stainless&#x2F;copper threads).<p>Also, not every type of connection takes dope&#x2F;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&#x2F;compression fittings.<p>Also, plumbers get paid a lot because it&#x27;s generally heavily regulated - water supply contamination is one of those things we&#x27;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&#x27;t screw into the other, since the threads have different shapes and are at different angles.

Bsp, Npt, goop (yuck!), and teflon tape are all inferior to Swage. Cold weld and reuseable but it is a trade in itself to fit and bend to place.<p><a href="https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Compression_fitting" rel="nofollow">https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Compression_fitting</a><p>Working in labs on fluid and vacuum lines (&lt;1in diameter) this is the way.<p>If only it wouldn’t cost as much as the house in fittings + tube to hardpipe stainless fittings on our water supply lines.<p>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&#x27;re paid so much because you need to pay twice for the bad ones. My house&#x27;s previous plumber threaded a copper line directly into the stainless steel DHW tank. That wasn&#x27;t a problem, until it was.

Blog updated and the following added:<p>Thanks to all the good people on Hacker News for their input, from which I&#x27;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&#x27;t mess with gas.

I thought they were paid so much because plumbing is gross and often just a huge pain.

Given the choice, I love pex and those compression-bands that you put on with the special pliers. Pex got flex.<p>For drains, pvc of course.<p>Given run-of-the-mill refurbby waterline junk with plain ol copper, I like that brass kind of compression with the little sleeve.<p>Don&#x27;t trust sharkbite. Am a mediocre sweater.<p>For gas, threaded with that pipe goo works surprisingly well. Haven&#x27;t fucked it up yet.<p>I wonder if you can use pex with gas

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.

Because they are licensed, and the license requires the equivalent of apprenticeship.

Programming is analogous to a trade like plumbing in many ways imo.<p>* You both design and then build a thing.<p>* No one else knows how it works or cares until it stops working.<p>* Through work you build up your own set tools and methods that you like and can apply to various jobs.

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.<p>Seeing that American can&#x27;t even adopt the metric system, I have little hope for a clear international standard for pipe fittings.

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.<p>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.

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

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.

That&#x27;s funny. I literally just finished installing a new kitchen sink and faucet at home. Holy crap was it a pain in the ass.

I would personally recommend trying TFE paste, rather than Teflon tape. Easier to get a seal, less annoying to tighten.

Nope. It’s the backbreaking work in tight places with a high probability of wallowing in shit.

Best. Conclusion. Ever.

This article sucks. Lots of bad info from an inexperienced plumber.<p>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.<p>Also, DO NOT buy the cheap PTFE tape as suggest. Buy the milspec tape. Your big box store will have both and you&#x27;ll know where that money (a couple dollars at most) went.

i got worried at this point:<p>&quot;imagine putting a tapered male in a straight female&quot;