British Standard Pipe size

KBP&H_2

I'm in NJ, we constatntly get chinese or other nipples w/ a different taper as most supply houses only carry this ****, When I complained to a state inspector ( DCA) they said they know about it but don't fail for it or say anything,, So what's deal,? We Americans are selling out on this cheap stuff but the very wealthy are buying this stuff such as THG,and other stuff but no one addresses the problems besides the last guy in line!

KBP&H_3

BRITISH PIPE THREAD TO AMERICAN

What's the best to connect BSP threads to american, An american male adapter screws and bottoms out to female BPS and American female only goes on about 1 ( ONE) turn,, Kinda plumbing Q but thanks for looking ( there's NO site like Dan's!)

Ken_40

BPT...

We found four or five revs of teflon tape would allow decent take up on your first dilemma, and using NPT taps and dies on smaller diameters could used on certain apps.

The manufacturer's should provide or tell you where to get "adaptive" transition fitings/nipps. But if they did, you probably wouldn't be here looking for solutions - would you...

Sorry. There was also a Britsh thread size called Whitworth as well. That animal is all but defuct now as I recall, but lots of older stuff is out there. Again, I would ask the manufacturer how to make the connections.

Plumdog_2

Whitworth

When I used to fix Triumph motorcycles I accumulated a fair selection of Whitworth spanners and such. If I recall, the spanners had nominal (in name only) designations that referred back to the dia. of the bolt rather than the width of the nut; so flat wide nuts would sometimes have the same name as short tall ones. Long live the queen.

Brad White_9

Whitworth

appropos of nothing:

Whitworth made the finest rifles used in the "Civil War" ("War of Northern Agression" or "The Late Unpleasantness" if you prefer )

Even in the 1860's, incredible craftsmanship and accuracy to 500 yards....

In the famous last words of Union General Sedgewick, "They could not hit an elephant at this dist..."

Seattle Nick

How did I miss that about Joseph Whitworth, Brad? Now I know why he was able to have his standardized thread system adopted.....he could back it up with firepower!

Seattle Nick

Somewhere in the world the adapters are made: BSP NPT Adapters
Have you tried the supplier of the equipment?

Scott Denny

BPS adapters

If SeatleNick's site is a bust, try this one:
http://www.adaptall.com/F-MetricConversion-steel.htm

KBP&H_3

THANKS

Watts Eurotherm 1 1/4 male valve body for a shower,, Watts supposably doesn't have adapters tp NPS ( so I'm told), one company making the valve, another the trim ( THQ) Gonna give it a try but were running 100-125 psi, ???? Thanks for the input!!!!

Scott Denny

THG

I believe that's THG, not THQ. They're a French Company that makes thermostatic inwalls as an OEM and a complete faucet line under their own logo. If you're planning to connect to the bottom of the valve, they make an adapter. However, if you're planning to connect to both the top and the bottom of the valve, be warned that there is a temperature differencial between top and bottom. Here's a link to THG:
http://www.thgusa.com/products.php?parent_id=_32_45

Seattle Nick

Good info, Scott! Thanks

Nick

KBP&H_3

Yea-- sometimes they don't tell you that

All thermostatic valves are the same, they mix the water almost outside of the valve body,, and Like You said, if you use both at the same time there can be a 3* + temp variation,, sorry about the THQ thing, that 's the mx deal.

Bill Nye_2

Maybe ?

Maybe you could get an adapter from Viessmann or Buderus? In the past when I have installed their water heaters I was provided with brass adapters for BSPT to NPT.

Also, some hemp. Put some pipe dope on the male thread and then a few wraps of hemp. Trial and error wiil determine the correct amount of hemp.

I think Buderus gives you teflon rope now. You wrap it in an irregular pattern on the male threads.

I like a really sticky dope like hercules grip or grip lite or maybe good old fashioned permatex.

Christian Egli_2

Pipe threads to screw yourself with NPT BSP oh la la!

I'm only talking about pipe threads here, National Standard Taper pipe thread and British Standard Pipe thread (which covers Europe).

NPT stuff we have here is taper male and taper female, in BSP, the female is not taper, it is straight. There is nothing incompatible on this point about making a tight fit, just that when doing so with a straight female, you've got to use gobs and gobs of Teflon, just like the Europeans do. Just Teflon paste is not enough.

The big issue though is the nominal size. Here, there is a huge difference that will break everything. [Before I go on, I think whoever created this difference should be hanged -but he's probably dead by now while countless catastrophes happen daily because of him]

You know how we spell color and others spell colour? The difference is whimsical and immaterial as far as dictionaries go. The same can't be said of pipes.

Threads are defined by a diameter and a pitch (listed in thread per inch for pipes). To mate a fitting you need homomorphous diameter AND pitch. While you can handle a bit of slop in diameter (because the taper will catch it up), YOU CAN'T HANDLE ANY (NONE AT ALL - NONE) DIFFERENCE IN THREAD PER INCH COUNT. I'm not yelling at anyone, I just want it that loud enough.

If your try ignoring this, you'll strip the thread and everything will come apart when you turn on the pressure, plus, you won't be able to get a tight fit.

Observe the discrepancies between NPT and BSP, I list the diameter and the thread per inch.

BSP 1/16-28; 1/8-28; 1/4-19; 3/8-19; 1/2-14; 3/4-14; 7/8-14; 1-11; 1.1/4-11; 1.1/2-11; 2-11; 2.1/2-11; above-11

NPT 1/16-27; 1/8-27; 1/4-18; 3/8-18; 1/2-14; 3/4-14; 7/8-11.5; 1-11.5; 1.1/4-11.5; 1.1/2-11.5; 2-11.5; 2.1/2-8; above-8

Pay close attention to how 27 is not 28, 18 is not 19, 11.5 is not 14, and most stupidly how 11.5 is not 11. Even though this .5 difference seems small, you can't ignore it. It explains how you can't screw past one turn.

The only compatibilities exist for 1/2-14 and 3/4-14. The guy I want to hang must have been ashamed of himself trying to invent, say a 14.3 pitch, for those two most used sizes. Either that or Mr. Whitworth did put his rifle to good use, just not enough bullets.

KBP, don't try forcing unless we're talking 1/2, 3/4 inch only. Perhaps the neatest way to go is to size your 1.1/4 holes the way you need them using metric taps or threading machines. If you're near Dayton, perhaps I can help. Do you just need a nipple or is it some kind of cover?

Finally, another word of caution.

You can fit a 5/16 screw in an M8 threaded hole. It seems good... until you tighten and you strip everything. Then you start pulling out your hair in agony over how you'll fix this. Countless engine blocks must die every year from this type of carelessness. In the USA, you have to be able to identify all threads all the time and you have to have the tools to investigate size and pitch, for your safety. Just like you need a rifle. Thanks for the notice, Brad.

bob_46

What

Christian says plus the thread angle on NPT is 60 degrees on BSP it's 55 degrees(Whitworth). The crown and root of NPT is truncated flat on BSP it's round.

Brad White_95

Is there any better

treatise than this, uh, thread? Thanks, Christian- astounding as always.

Brings me to another question: Viessmann Vitodens 6-24 has 3/4" BSP connections and adapters. Comforting that the pitch is the same as you so well explained.

Both ends seem to fit interchangeably to my eye. The adapter, being female, it is all the more difficult to find a taper (without OB-GYN instruments I am just, um, speculating here)....

Both seem to fit either equally well. Aside from gobs of teflon or wick, is there a sure-fire way to tell? I could not find a stamping on the fitting, Obi-Wan.

Brad White_95

Hexagonal Bore

This fellow was ahead of his time... An unheard of 1500 yard effective range and 500 yard shots, then the hit-or-miss standard, was a breeze. Bore was hexagonal, yes, six-sided, with .45 projectiles to match. The machining to do that had to have been incredible!

(I imagine, savagely, a sniper asking to borrow a round from his buddy and given the response, "right hand twist or left hand?")

Not firepower, Nick- accuracy! Do it once, do it right.

Christian Egli_2

Not that there is anything wrong with that

The Viessman female adapter is then probably just what we would see as the one end protection straight nipple that comes with new full length pipe. If it were taper on one side of the fitting, you should see an obvious step inside its middle or see a disappearing crest on the thread as you get deeper. Either way, there is not much wrong being straight, it works with lots of tape.

A nice substitute for accurate plug gauges to test threads is to try the fit with a tap. Taps are accurately ground, and clearly labeled with the identifying thread.

Improper taper or lack of it will show up as a wobble you can feel as you screw the test tap in by hand. With a proper taper, the wobble fades out until you get a sound stop. With straight thread, it does not disappear so neatly. A tap will cut its own new thread if you force it in, for testing purposes go gentle and by hand.

Getting taps in BSP (the tap itself is straight too) allows for more fun comparative testing. Plug gauges would be the ultimate test.

Other measurements

With the use of a caliper, the presence of the taper should be plainly obvious. A caliper, a set of thread gauges and corresponding standard tables is all you need to get a long way debunking magic threads.

Now, you're armed to look at everything you buy.

Government regulations having forcibly shut down most of our foundries (and brass foundries in particular) it's no surprise everything comes from other enterprising countries. Indeed, most supply houses here sell Chinese fittings, while I remember the ones that didn't have plumb thread, I must say, those problems seem much improved nowadays. I don't seem to see much of Thailand and Mexico fittings either; they were the rage a few years back.

LarryC

BSP-NPT adapters

McMaster-Carr stocks and sells BSP-NPT adapters.

Plumdog_2

Brirish Steel

currently restoring a '57 BSA rifle in .338 mag caliber. After sight-in session; my son quipped "that bad boy gots some BASS to it, dude". Long live the queen.

bob young

various threads

And then you got your faucet seats and spindles ---- sizes and threads. each company has about a million ---all different. i believe savoy had ten million

Bernie Riddle_2

An easy way to verify that the male and female threads per inch are the same is to take a 1/2" strip of paper, and press the strip, with one finger, on the female thread, and slide it on the thread to make an exact impression of the thread. Then lay the strip on the male thread and see if it is the same.

Seattle Nick

Hmmmm. Not so sure about the untapered female thread part. Have a look here:

More BSP BSPT BSPP B.S.

Seattle Nick

Hmmmm. Not so sure about the untapered female thread part. Have a look here:
More BSP BSPT BSPP

Plumdog_2

thankyou

Scott Denny

Christian
I recently installed 2 outdoor exposed shower units marketed by Sonoma Forge. See:http://www.sonomaforge.com/faucet/shower/shower02.html
I experienced a leak at the field installed 3/4" strait thread screw in joint between the riser and the arm on both. To test whether the leak was caused due to a faulty riser or arm, the manufacturer sent me a strait thread x tapered thread nipple with a cap on the tapered end. Even with gobs of tape and dope the tested joint leaked somewhat. Locktite here I come. From my experience, the only strait thread joints I've never had trouble with are those that seat against a flat surface and are designed to have a felt gasket sandwiched between male and female faces. Since the shower riser had a female strait thread adapter brazed to the inside of a larger diameter piece of tubing and had no such flat seat, I'm recommending to the manufacturer that they change their threaded connections to NPT, thus eliminating the need for gobs of goop or gaskets.

Christian Egli_2

A wink, a secret hand-shake and a pot of grease

Perhaps the outdoor shower head manufacturer should have billed you an extra charge for a multi port-full splash showering system. Call it re-engineering. Thanks, Scott for sharing.

What European plumbers use is very old fashioned hemp in combination with very antique tallow like ointments. These reduce leaks to a slow, very slow seep which eventually rusts everything shut. And it works for them.

Notice the profusion of non screwed fittings that are used in Europe? Notice how much they bend pipes rather than use elbows? Everyone hates non tapered threads while we have the good life here with our NPT pipes. An outdoor shower seems like a lot of cool fun.

I have a picture somewhere that I took at a department store in Germany, fancy deluxe utility faucet, Jetson age compression fittings, post-modern pex-al-pex tubing, slip-joints, the full complement of expensive anti-leak proof connectors and yet, somewhere along this showcase piping there is a taper male to straight female junction with all its unkempt greasy long hair - and it is leaking.

Perhaps Messrs. Whitworth and Sellers should have sat down together and shared their good ideas. Joseph Whitworth was the one to first come up with thread pitch numbers in 1841 which William Sellers thought "smart" of screwing with in 1864, but Sellers was the one to go taper - taper. Sellers was leaking a lot of info the US Navy Bureau of Steam Engineering was coming up with during that period.

It all comes back to our common steam ancestry, doesn't it? Perhaps one reason the Europeans did not court the beauty of steam heating is precisely because they did not have the good pipe fittings. Using a lard grease mixture does not seem to me to be the ideal way of sealing melting hot steam pipes.

We're on to something here. Meanwhile, modern steam in Europe is done with all welded connections and flanges.

Thanks Nick for the excellent article you found, I had fun reading it and learning from it. I don't think I said anything contrary to your information, it seems evident that BSP standards should exist for both taper and non-taper since these two both exist in the BSP gendered world, and thus both have to be standardized. The article mentions the wide use of taper male to straight female for common applications and... it also warns of the leaks that become unmanageable at higher than common water pressures.

For those problems, the BSP people should use taper - taper or straight - straight thread with sealing washer. Mostly, high pressure hydraulic oil hook-ups use positive sealing washers or compression fittings, so I am not sure how much of the BSP taper - taper connections are actually used worldwide. I am hoping someone else on line will tell us more.

Some fun now

The Colder text lists the BSP taper as 3/4 inch in a foot and the NPT taper at 1 in 16, which, unless my adding machine stands corrected, is... exactly the same thing. Whitworth and Sellers were winking at each other