Gas supply 15mm into 22mm

[giblets]

35mm sleeve.

 

[Biggles..]

technically giblets is spot on. lightning would do what most do.

a gas pipe needs 3mm clearnce all round therefore 22mm OD needs 28mm ID.

Thats todays useless bit of info out the way.

 

[croydoncorgi]

Of course you're right about what the standards say about sleeve sizes.

But I still can't understand what logic applies to having a HUGE gap between sleeve and pipe.......can anyone enlighten us?

(In practice, I reckon it would be safer to have 28mm copper sleeve around a 22mm gas pipe than to use a 32mm plastic waste pipe.....)

 

[Agile]

Its probably based on that expectation that there is going to be massive differential subsidence between the inner and outer leaf of the cavity wall.

The purpose of sleeving is partly to trap any gas leaking from the 22 mm tube within the wall thickness and also partly to accommodate any subsidence in the wall.

When did anyone last see a straight 22 mm tube start to leak? Or any differential subsidence between wall leafs?

Of course in the Midlands there is sometimes considerable subsidence and some homes are obviously significantly tilted. But they are usually solid wall homes and the whole house tilts following coal mining.

Tony

 

[chrishutt]

I still can't understand what logic applies to having a HUGE gap between sleeve and pipe.......can anyone enlighten us?

I assumed the point of having a few mm gap between pipe and sleeve was to allow for a sealant to be introduced. With a 28mm sleeve (25mm bore) around a 22mm pipe you have a gap of 1 to 2 mm between the two, which makes getting non-setting sealant in very fiddly. 32mm bore sleeve would give a gap of around 5mm so sealant can be easily introduced.

 

[doitall]

Commercial pipework the gaps is 6mm up to 80mm and 13mm above that.

 

[megawatt]

If you sleeve in 35mm squirrels will be crawling in

 

[giblets]

You must have some mighty lean squirrels down there, MG!

Big fat beasties up here.