plumbing thread size

[captainforbes]

I need to replace the broken tap/shower outlet in the heads basin on my 2004 Dufour 40.
I have sourced a likley replacement, but there is a choice of fittings: 1/2" BSP (M), or 15/1 (F).
How do I tell the differenced? I don't want to order the wrong part.

 

[roboandkate]

1/2" BSP has an od of 0.825" and 14 tpi, a vernier and thread guage are the best way of determining this, I don't know what 15/1(F) is.

There are so many odd ball sizes in pumbing I usually take it down to our local merchants and get them to try all the nuts they have in the place until we find one that fits, or they throw me out.

 

[captainforbes]

so if I measured the outside dia of the thread with a vernier and it was 0.825" it would most likely be 1/2"BSP? What is 0.825" in mm? My vernier measures inches in 16ths or something, not decimals. Much easier in mm?

 

[daveyjones]

most plumbers would be able to tell at a glance what the thread was - although it is true that there are many strange threads used in plumbing, in practice they boil down (at least in recent years) to a few standard ones, like metric and BSP. Rather than mess about with verniers and threads-per-inch (sounds totally obsessive and pedantic to me) just take the part down to your nearest plumbers merchant and ask for something that fits. Keep a note of it, so you'll know next time!

 

[daveyjones]

By the way, taps and showers are nearly always half-inch BSP, so if you have to order without seeing, go for that. If you're wrong , you'll know better next time.

 

[jfm]

You can buy any old 1/2bsp fitting like a nipple, for about £1 from plumbers merchant. So do that, take it to the boat, and if it screws on to your boat thing ok, then it's 1/2 inch bsp innit!

Remember bsp comes in straight and tapered. you can eyeball your boat fitting and if it's the tapered version twill be quite obvious

 

[asj1]

The ASAP catalogue has pages and pages of marine plumbing parts and useful tables explaining thread sizes and types. Only last week I found the catalogue invaluable in identifying and ordering parts.

If you order from them do it by phone and not over the internet, as their internet system is not linked to their ordering or stock system, but is in effect just an email system looked at once every 24hours. This means that it is slower and you have no idea if things are in stock or not.

 

[davehu]

1/2 inch BSP male thread measures 0.8250 inches ( approx 21 mm) on the outside diameter and has 14 threads per inch. A 15/1 thread is I presume a metric thread 15 mm in diameter and has 25 threads per inch. Hope this helps, The BSP thread sounds OK the metric thread seems rather non-standard

 

[alienzdive]

Possibly the M and the F are for male or female connections,
Shower fittings are usually one or the other.
Again, most plumbing shops stock both of these and would probably take the other one back, even though they are £2 each.

If you take the other end in they will match it for you.

 

[snowleopard]

[ QUOTE ]
I have sourced a likley replacement

[/ QUOTE ]

My shower head is also duff and I haven't been able to find a replacement yet. Would you mind sharing your source?

 

[Anchorite]

Re: There was a young plumber from France...

Steel pipe sizes have different names Imperial/metric but are the same. The imperial size is not e.g. one inch but has a standard OUTSIDE diameter of 33.7 mm (not exactly a round figure in inches - about 1 " 21/64ths). The INSIDE diameter depends on the wall thickness. Continental usage for BSP is DN (nominal diameter) + size, standardised as follows (for just a few common sizes): DN15 (1/2"): DN20 (3/4"): DN25 (1"): DN40 (1" 1/2): DN50 (2"). Threads are identical, as BSP is the European standard.