How do you work out the size of a pipe

[dazzammm]

Hi,
ive got a leaky pipe (see other posts) but am looking to get a new stop tap.

how do you work out the size of a pipe?

(i measured the circumfrence which was 53mm which gave me a diameter of 17mm which made me think i need a 15mm stop tap. bought it but its length is 3/4" too short)

 

[dazzammm]

ive just thought. my house is a 50s house so the pipes are probably in imperial measure. Are the current sizes and pre decimalisation sizes the same?

 

[Boilerman2]

what matereial is the pipe made from, also try and mesure the pipe with a veriner gauge 1/2" copper is the same as 15mm - 3/4" copper is not quite the same as 22mm but you can buy a 3/4" olive to put into a 22mm stopcock

 

[dazzammm]

its copper. just looked at the stop tap and its got 1/2 stamped on it but its bigger and chunkier than the 15mm ones ive seen.

i did think the pipe size looked about right but ive still got a stop tap thats 3/4" too short.

Plan C is to put a blank nut where ive got a leak as the supply is not used - im assuming i dont need an olive for that.

additional - just been googling and discovered that its probably an old 1/2" BSP stop tap

 

[Charnwood]

1/2" copper is the same as 15mm

1/2" imperial copper tube is actually 16mm - 5/8".

A lot of compression valves have imperial sizes cast on them, but are actually for metric pipe.

 

[dreadnoughtheating]

Sorry Charnwood, 1/2" copper is not 16mm, most if not all '15mm' fittings can be persuaded to fit with minimal intervention.

To the OP, can you upload a photo of both the original stop-tap and the replacement one you bought?

DH

 

[Charnwood]

Sorry Charnwood, 1/2" copper is not 16mm, most if not all '15mm' fittings can be persuaded to fit with minimal intervention.

If it has to be persuaded then it is not 15mm. 1/2" imperial copper is, so I've been led to believe for 40 years, aproximately 15.8mm, as close to 16mm as damnit. Some compression manufacturers - Conex, for one - did 16 x 15mm couplers as adaptors.

I might be wrong, but.....

 

[matt1e]

Sorry Charnwood, 1/2" copper is not 16mm, most if not all '15mm' fittings can be persuaded to fit with minimal intervention.

If it has to be persuaded then it is not 15mm. 1/2" imperial copper is, so I've been led to believe for 40 years, aproximately 15.8mm, as close to 16mm as damnit. Some compression manufacturers - Conex, for one - did 16 x 15mm couplers as adaptors.

I might be wrong, but.....

1/2 in converted to mm = 12.7 mm (internal diameter)
outside diameter of 1/2in copper = 0.625in

0.625in converted to mm
= 15.8mm

so no, you are not

Matt