1/2 inch BSP tap tails

DanS · Post by **DanS** » Thu Jun 04, 2020 7:20 pm

Hello

Can anyone advise where I can source tap tails (copper of flex) for a monobloc tap that come with a 1/2 inch BSTP male thread, for insertion into the tap bloc.

Does that sound an odd size?
No plumbers merchant I have been too has ever seen this, but most are young lads and I suspect this is a 20+ yr old tap and before their time

I've measured it with vernier calipers to confirm and it is 1/2 inch (0.54) or in mm, 13.7mm.

I can't find any reference to 1/2 inch monobloc tap fittings online.

The tap is solid and great condition. I don't want to bin it for the sake of a tap tail.

As another option, I found 1/2inch (male) to 15mm pipe adaptors

( See toolstation /tap-tail-adaptors/p14081 )

But, they don't have o rings, and no way to tighten them, so dubious I'd get a seal. Has anyone used them?

Any pointers appreciated.

Chippo1 · Post by **Chippo1** » Thu Jun 04, 2020 7:39 pm

That’s not ½ BSPT , it’s to fine a thread and is not tapered , your measurement on the vernier looks more like 14mm.

½ inch BSP Pipe thread relates to the pipe bore not the OD of the thread And 13.7 is nothing like ½ inch in any case it’s roughly 12.7mm.

So try looking for 14mm straight metric thread , my eye tells me it a metric fine thread maybe around 1.25 pitch

DanS · Post by **DanS** » Thu Jun 04, 2020 10:35 pm

Hey chippo
Thanks for the input.

The angle of the photo doesn't really help: Pretty certain it is tapered and that it's less than 14mm. The camera lens is off to one side so the vernier lines are at an angle. But no real matter.

Assuming it's either 14mm OD or 13.75 or OD, I'm struggling to source a replacement tail head. Neither 14mm or 13.75mm OD exist as a standard plumbing fitting as far I can see, which is what brought me to assume it must be imperial. And half inch is closest.

As an aside, A question on BSP : i appreciate the measurement is ( or at least was originally) about the internal bore. The thing I don't get is, how do you work out the OD thread size from the bore measurement? If the pipe wall is 1/8 inch thick, the OD size is very diff compared to if the pipe wall were 1/16th thick.
A half inch BSP pipe will always measure more at OD than half inch but, depending on the wall thickness, it's going to vary...how on earth do you calc the OD thread etc?

Back on topic though, the female part i am trying to fit into is a little over 0.5 inch ID (about 13 to 14mm.)

And I can't find a tail that size. I don't believe I have the only, unique, one off tap with a weird tail fitting of this size, ever made. So i guess the question is, what's the likely 'standard' fitting this could be, and then, does anyone know where to source one in a world where M10 and M12 is the norm.

Thanks.

DanS · Post by **DanS** » Thu Jun 04, 2020 11:01 pm

I may need to eat my words Chippo.
Seems 14mm does exist. I found one hit online for 14mm, at screwfix of all places.

Will give it a go and see if it fits,
Thanks

Screwfix dot com /p/flexible-tap-connector-14mm-x-x-500mm/5285g

Chippo1 · Post by **Chippo1** » Fri Jun 05, 2020 7:47 am

There are tables on the internet showing the sizes of Bores and OD of BSP pipe , which is still used the world over despite the general adoption of the metric system other than for the Luddite,s across the pond.

The BSPT option would not normally be used as the seal is provided by the O ring , taped threads get tighter the further joint forms using a sealant medium to complete the seal. I have dealt with lots of pipe work up to 3inch in the past with BSPT threads on low pressure hydraulics (100bar) using PTFE or Loctite as the sealing medium ( I think it was 246 ) trouble with loctite 246 was if you had cleaned and prepped properly you couldn’t ever undo the joint unless you heated it to close to red hot . I have crushed 2inch pipe with 4ft stilsons trying to undo a joint.

Grumps · Post by **Grumps** » Fri Jun 05, 2020 10:16 am

I think what you have used to be known as 12mm tails.

Try

from Screwfix.

https://www.screwfix.com/p/flexible-tap ... pack/5891g

DanS · Post by **DanS** » Fri Jun 05, 2020 11:02 am

Chippo, Thanks.
I'll stand corrected on the tapered. It seems v slightly tapered but I've not compared to an actual tapered, so given your info, it's probably not, especially given the o ring etc.

DanS · Post by **DanS** » Fri Jun 05, 2020 11:04 am

Grumps,
Thanks. It's not 12mm. I have tried those parts.
The female bore measures nearly 14mmm and the male thread measures 13.7mm OD.
12mm is too small.

Dave54 · Post by **Dave54** » Fri Jun 05, 2020 1:57 pm

Pipe threads can be complicated because there are so many.

There's BSPT (tapered)
and BSPP (parallel)
Blowing that shot up it looks like a rounded top on the threads which means it might (might just) be 1/4" BSP, although that's 13.157mm (you wouldn't normally measure it in metric)
https://en.wikipedia.org/wiki/British_Standard_Pipe

If the taps are American, it could be NPT, which'd be 13.7mm or thereabouts.

If that's 15mm copper I can see attached to the threaded part, I'd connect to that and keep the final fitting.

Or change the tap.

DanS · Post by **DanS** » Fri Jun 05, 2020 3:20 pm

thanks Dave54,
US NPT sounds bang on at 13.7! Good knowledge. I'll look into that.

The copper you can see is the end of a copper tape tail at 12.25mm OD.

Managed to re solder the 12.25 copper to the brass male screw shown. It will hold, but the spanner faces are knarled and rounded and not easily tightened when under the sink (lack of room etc) so I'd rather replace if I can. I'll look at NPT and 1/4" BSP options.
Was 1/4" BSP a standard size for domestic plumbing/taps?

Cheers

Dave54 · Post by **Dave54** » Fri Jun 05, 2020 3:35 pm

I'm not a plumber, although I've done a bit, and done some pipe fitting as well in the factory where I used to work.
BSP was probably the most used thread here in the UK, and AFAIK still is. Most domestic threaded stuff for water at least is 1/2" or 3/4" though.

You'll get adaptors from copper to 1/4" BSP easily enough. NPT I reckon it'll be more specialist. You find it on industrial or (I think) medical stuff sometimes.

Start by asking BES in Brum.

DanS · Post by **DanS** » Fri Jun 05, 2020 3:46 pm

Cheers Dave54, will check out BES.

Assuming the right thread, do you think something like this will form a seal if I inset into the tap instead of the tail? Cant see how it seals without an o ring and no spanner face/nut to tighten it up as a compression fitting....

https://www.toolstation.com/tap-tail-adaptors/p63663

Dave54 · Post by **Dave54** » Fri Jun 05, 2020 3:51 pm

No, they're for connecting the copper to the type of flexible with a "swivel" type 1/2" connector at one end AFAIK. The plain end will be the same size as 15mm pipe.

You need the same type as you took out with the o-ring.

Like I said earlier, if it's too much hassle I'd change the tap.

DanS · Post by **DanS** » Sat Jun 06, 2020 11:53 am

Thanks David
Repaired tail is holding.
Am astounded it's so difficult (impossible) to find a replacement tail that fits.

dewaltdisney · Post by **dewaltdisney** » Sat Jun 06, 2020 12:08 pm

I always go on about tap fittings and valve cartridges, on quarter-turn taps especially. The replacements can cost an enormous amount as many taps do not have a standard cartridge with varying splines, threads, and body lengths. There should be standards set to prevent this so when you buy you can see the cartridge replacement type and buy accordingly. I would never buy an expensive fitting as these tend to be the worst to fix if they go wrong. It is often cheaper to just put a whole new unit in in some circumstances.

DWD