Do size matter

[Montycaboodle]

Hi All
Can anyone tell me if a 15mm pushfit will fit the old half inch copper pipe, Reason i want to add an outside tap and the nearest pipe happens to be the old half inch.
Many thanks
Montycaboodle

 

[ChrisR]

Yes but expect it to leak considerably at some point. You can buy pushfit adaptors.

 

[Slugbabydotcom]

Theres no difference between 15mm and ½"imperial copper pipe The only problem I can foresee is if the pipe has expanded due to being frozen in the past. Use a pipecutter rather than a hacksaw when you cut this pipe as the raggy bits will damage the rubber 'O'ring in the push-fit fitting you could file them off but proper pipe-cutter is manufacturer recommended.

It's highly unlikely that the pipe you are referring to is actually ½"OD pipe which is a different animal usually found in LPG and industrial applications but I'm just letting you know of its existence just in case .

 

[ChrisR]

SLug you must be young?
Imperial sizes, so Half inch pipe, was the normal size up until the early 60's I think. Anyway there's loads of it around still. It is NOT the same size as 15mm. Half inch was measured Internal diameter, 12.7mm, and 15mm is measured OD and is a bit smaller.

 

[doitall]

SLug you must be young?
Imperial sizes, so Half inch pipe, was the normal size up until the early 60's I think. Anyway there's loads of it around still. It is NOT the same size as 15mm. Half inch was measured Internal diameter, 12.7mm, and 15mm is measured OD and is a bit smaller.

Can I join in

1/2" is compatable with 15mm.

3/4" is slightly smaller than 22mm.

1" is compatable with 28mm but can be tight in with some fittings.

11/4" and 11/2" well you don't use that size anyway but one fits and one you need a convertor

 

[ChrisR]

For pushfit, at least some of the makes, 1/2" is not compatible with 15mm. They make adaptors to go between the two. If you put a 1/2" pipe in a 15mm fitting you will be stretching the O ring beyond its design.

For copper pipe fittings, the two sizes are usually sufficiently close that they are interchangeable, but some 15mm compression fittings are too tight to accept a 1/2" pipe. Others like Conex will take either. Some 15mm olives won't go on 1/2" either.

From BES, Speedfit:
Connects imperial to metric pipe.
Suitable for central heating systems.
Part No. Description Unit Price
7108
1/2" i.d. x 15 mm
£1.28

 

[fitz1]

I think chris is referring to the old grade one copper, which i think is slightly bigger due to the thicker wall.

 

[ChrisR]

Rubbish. I am referring to the imperial standard 1/2" copper tube which everyone had. It is not, was not, and never will be the same size as 15mm. They are a different size . OK?

It has got absobloodylutely nothing to do with the wall thickness!

 

[Slugbabydotcom]

SLug you must be young?

They used to call me young slug back in the 70's and 80s I'll take that as a compliment

Spent the winters of 82 and I think 83 doing little else than repairing burst pipes in outhouses on mostly post war and some pre war council housing . Do remember having problems with a few jobs but I put that down to the pipes having expanded due to freezing and expanding but not bursting. The older pipes were a lot thicker than they are now and I got away with carefully filing the pipes down a bit in the worst cases and getting a conex on them, kuterlite fittings were a ball ache. Acorn fittings now known as Hep20 had only just come out then.

Theres no difference between 15mm and ½"imperial copper pipe

Half inch was measured Internal diameter, 12.7mm, and 15mm is measured OD and is a bit smaller.

I should have been more specific then and said that theres no significant difference as the difference is approximately equivalent to a gnats knacker

I only use Hep20 pushfit and what follows only applies to that
Ok if 15 is slightly smaller which I concede, that means the 'O' ring in a push fit should be a bit tighter and the fitting harder to get on a ½" pipe. Assuming the joint is lubricated with silicone and the pipe cut properly so that the o ring doesnt get sliced up when pushing the pipe in the joint should be sound. If it doesnt leak at the start it never will.

If you put a 1/2" pipe in a 15mm fitting you will be stretching the O ring beyond its design

.
I have confidence in Hep20 that they can take it, backed up by the fact that they only have a provision for ¾ imperial pipe on the following web page http://www.hep2o.co.uk/v2OConnection3.cfm

 

[Montycaboodle]

I would like to thank one and all for their help in this matter.
I will try an adaptor and will let you know the result.
Thanks all again
Montycaboodle

 

[ChrisR]

Hep don't do an adaptor for 1/2" so you might assume that their 15mm will be OK but that's not an assumption an Engineer would make. There are several other near-equivalent sizes which would not fit. That's how cock-ups happen.

If it doesnt leak at the start it never will.

I wouldn't be that optimistic, having seen a score or so hep pushfits start leaking some time after installation.

The whole point here is to dispel the untruth that 15mm is the same as 1/2".

Whether the difference is significant depends on the application. If the pipe doesn't fit the fitting, I'd call that signficant!

 

[blahblah]

Fitted a half inch to 15mm speedfit adaptor to connect old to new copper. Assumption being the mother of all upfucks -pipe wasn't half inch after all but 15mm, hence half inch too loose. Got very wet!