Detecting a gas pipe

[rogerzilla]

Slight hitch in the wood-burning stove plans: when our house was built in 1981, B*vis Homes helpfully ran a gas supply into the lounge for an optional gas fire, which no-one ever fitted.  There's a little capped-off outlet stub projecting from the wall just above the skirting, and predictably a vertical line from this is very close to where the flue for the stove needs to go through the wall.

We think the pipe runs between ceiling and floor and drops down to the outlet, because we had a patio door installed a few years ago and we know the pipe doesn't run through the walls.  I doubt it would be buried in the floor for safety reasons.

Three questions:

1) if the pipe is in the cavity between the two leaves of the wall, rather than between the dry-lining and the inner leaf, will a pipe detector still find it?

2) is there any way to detect if it's "live" without cutting it (which would then require someone CORGI registered to solder it back up again)?

3) how close can a stove flue be positioned to a live gas pipe?

The pipe could obviously be traced and capped off higher, but with the amount of replastering needed , CORGI plumbing rates etc, it makes the job unviable.

[TimO]

... and we know the pipe doesn't run through the walls.  I doubt it would be buried in the floor for safety reasons. ...

Don't bet on it.  In my brothers first house (relatively modern) the gas pipe was buried in the concrete floor.  When they moved the fire, they had to chisel a channel in the floor to get to it.

[Charlotte]

2) is there any way to detect if it's "live" without cutting it (which would then require someone CORGI registered to solder it back up again)?

Anyone can join a gas pipe back up or cap one off.  It's not hard.

Anyone can also make said gas pipe look nice and dirty and then claim that it was like that all along.

Apparently 

[rogerzilla]

Don't bet on it.  In my brothers first house (relatively modern) the gas pipe was buried in the concrete floor.  When they moved the fire, they had to chisel a channel in the floor to get to it.

If it is in the floor, it makes life much easier.

I'm glad I didn't hit it when fitting the downstairs toilet 

[rae]

Knock a small amount of plaster out around the stub to confirm direction of travel - easily fixed, and every house I've ever seen has gas through the floor - although I only "do" old houses.   A decent pipe detector (not a £15 piece of junk from B&Q) will locate it at a depth that is thicker than a cavity wall. 

Then wot charlotte said.   It's only soldering.   Remember to turn the gas off first.

[rr]

It shouldn't be in the wall cavity as this was made illegal after some very nasty explodsions.

[TimO]

It shouldn't be in the wall cavity as this was made illegal after some very nasty explodsions.

Hmm, so what if you need a gas pipe upstairs then?  Do you have to run it externally?

[rr]

It shouldn't be in the wall cavity as this was made illegal after some very nasty explodsions.

Hmm, so what if you need a gas pipe upstairs then?  Do you have to run it externally?

externally and straight through the wall in a sleeve. They are sometimes boxed in on the outside of the wall. Relevent part of the Regs here

[rogerzilla]

It shouldn't be in the wall cavity as this was made illegal after some very nasty explodsions.

Given that it was installed by Bovis Bodgers in 1981, it wouldn't surprise me.

[rogerzilla]

OK, the pipe detector can't find it so it's in the cavity, which may have been legal at the time the house was built.  I can see that if any CORGI-registered person so much as touches it, he/she will be bound to remove the entire pipe at a cost of hundreds of pounds.

[Basil]

I know a really easy way to detect a gas pipe.  Put up a spice rack.
When Mrs B and I were living in sin in Bristol I decided to put up a spice rack in the kitchen with a couple of those picture hanger nail jobbies.
Tap tap tap.  Ooh, that suddenly went in easily!  Pull out nail and psssssssssss!
Bugger.  It was a flat in an old victorian house.  I'd hit the feed to one of the old wall gas lamps. 
I was astounded that they'd not been cut off further down the line.

[Quisling]

Knock a small amount of plaster out around the stub to confirm direction of travel - easily fixed, and every house I've ever seen has gas through the floor - although I only "do" old houses.   A decent pipe detector (not a £15 piece of junk from B&Q) will locate it at a depth that is thicker than a cavity wall. 

Then wot charlotte said.   It's only soldering.   Remember to turn the gas off first.

If you follow this route, remember to turn off the gas first AND let the pipe vent off before soldering!  Better to disconnect at the meter and purge the pipe with inert gas first.

Better still, use a compression end cap.  Turn the gas back on and use leak detection spray to check the cap is tight before re-burying it in the wall, with suitable notes in your "house folder" as to its exact location.  For cheap leak detection spray use neat washing up liquid, smeared around the end cap, and then just wet it slightly and watch for bubbly bits.

If in doubt, pay someone else to lash it up.

[mrcharly-YHT]

Compression fittings are fine on gas. In fact, on a boat, you aren't allowed to use solder.