Why is it called 1/2 inch ?

[Ibrahim Kalay]

Hello,

Could someone please tell me why is it called 1/2 inch - 15mm standard blanking plug / bleeding valve?
Where ever I have measured I cant get 1/2 inch.

 

[ManchesterGas]

1/2 inch was the internal diameter of the pipe that was used with that size thread fittings

 

[SimonJohns]

It's 1/2" bsp thread

 

[ManchesterGas]

British Standard Pipe.

 

[chris watkins]

Should be BSPT really, which as you have all said stands for British Standard Pipe Thread, sized are 1/2", 3/4,1,1.1/4,1.1/2, 2" etc.
The metric equivalents are now being used 15,20,25,32,40,50mm a bit more.

 

[jtsplumbing]

It's a good old British measurement been used for years, not your foreign rubbish measurement's

 

[rpm]

Thought the T denounced a tapered thread, now where is the old Zeus book when you need it.

 

[tamz]

Anything with threads is in imperial sizes eg 1/4, 3/8, 1/2, 3/4 and so on and comes from, as Manchester gas said, the internal diameter of the relevant pipe.
In the UK we know them as BSP threads. British Standard Pipe. This thread comes in 2 types. BSPP (parallel) and BSPT (tapered).
This thread sizing also applies to European ISO standards where BSPP is known as G eg. G 3/4 and BSPT is R eg. R 3/4.

The thread on the plug and airvent are 1/2" BSPP or G 1/2

 

[rpm]

From what I can see there are 4 different BSP threads, one is parallel two are tapered with either a 55 or 60 degree taper but then there is another called BSPF which I think might be gas related.

 

[rpm]

tamz beat me to it.

 

[tamz]

BSPP is also known as BSPF (fitting). The threads are 55º. The same as Whitworth.

 

[Ibrahim Kalay]

Thanks for your replies.

I knew it was something to do with pipe rather than blanking plug / bleeding valve.

 

[chris watkins]

Anything with threads is in imperial sizes eg 1/4, 3/8, 1/2, 3/4 and so on and comes from, as Manchester gas said, the internal diameter of the relevant pipe.
In the UK we know them as BSP threads. British Standard Pipe. This thread comes in 2 types. BSPP (parallel) and BSPT (tapered).
This thread sizing also applies to European ISO standards where BSPP is known as G eg. G 3/4 and BSPT is R eg. R 3/4.

The thread on the plug and airvent are 1/2" BSPP or G 1/2

Thanks Tom, I stand corrected, you have also explained why T&P safety valves are denoted in sizes such as G 1/2 & G 3/4 etc.which I never new, still as they say, every day's a school day. :dunce2:

 

[Masood]

Anything with threads is in imperial sizes eg 1/4, 3/8, 1/2, 3/4 and so on and comes from, as Manchester gas said, the internal diameter of the relevant pipe.
In the UK we know them as BSP threads. British Standard Pipe. This thread comes in 2 types. BSPP (parallel) and BSPT (tapered).
This thread sizing also applies to European ISO standards where BSPP is known as G eg. G 3/4 and BSPT is R eg. R 3/4.

Ever thought about writing a book, Tam? Or making YouTube videos about plumbing principles, history etc? You've a head full of information that most of us will never come across unless people like you pass it on...

 

[kendod]

old school plumbing lol