I have a wall mounted balanced flue gas heater. The gas supply pipe (ordinary copper plumbing pipe) is buried in a channel in the floor screed that has been backfilled with a weak cement. It shares the channel with a c/w pipe for an outside tap. When I moved said tap, which involved excavating the cement in part of the channel, I saw no evidence of Denso tape or other means of protection on the gas pipe. A friend has suggested (very strongly) that I should cut off the gas supply to this heater at a point before the pipe dissapears into the cement. The heater was installed some 10 or 15 years ago.
My guess this would count as 'Immediately Dangerous' if leaking otherwise 'At Risk'. Should the channel become wet there is a good chance of corrosion which if left unchecked could well lead to a leak.
Quite right - you should also pull down any house walls that dont conform to the latest build regs while youre at it. And the floor might not use the latest spec of dpc... out it comes.
Get a grip. Corrosion to the pipe _will_ cause it to leak sooner or later. Leaking gas _will_ cause something bad to happen: choice of fire, explosion, or both. Damp doesn't have quite such dramatic effects.
By taking action now the OP can get the work done without excessive disruption and expense. If he waits until it starts leaking then it's likely to be a Transco disconnect and ID job and he'll prolly have to pay more to get it done in a hurry. That's if he's lucky and the leak starts slowly and he's alerted by the smell of gas before it can build up. If he doesn't notice it before he goes away on his summer hols and comes back to a nicely sealed house full of gas ...
Well such things are commonplace unfortunately,even though the relevant British Standard and the GSIR REGS indicate that pipework buried in this manner should be protected at least from corrosion. So called qualified people still do it now!.
Do you want to continue using the gas heater?. If yes and your not intending to rip up the floor for other reasons then I'd be tempted to pressure test your installation for leakage,if ok,then leave it. Chances are if it ever leaks it will only leak a small amount. Its
99.9% certain it wont be a dramatic failure. Even so,you;d soon smell it.
There are plenty of installtions which are defective in some way.Some of them will be being installed as you read this!!.
This from the Copper Development Association, publication 33:
4.8 Services embedded in concrete Copper has excellent resistance to corrosion by potable waters and is not attacked by normal types of cement, concrete or plaster. However, it should not be brought into contact with acid plasters, acid cements or coke breeze. Cement additives such as foaming amines should not be allowed to come into contact with unprotected copper tube, nor cleaning fluids which may permeate through screeds to embedded copper pipes beneath. The installation of tubes and fittings embedded within solid walls or floors is precluded except where it may be readily exposed, or alternatively if installed in a sleeve or duct which may be readily removed or replaced.
It would seem the OP's installation is OK as the weak cement means it can be "readily exposed".
In fact the main requirement for protection is because of the possibility of movement from failure of the floor (again from the Copper Development Association):
4.2.2 Copper Pipework In Solid Floors
When copper pipes are laid in solid floors they must be protected against failure by movement of the floor.
Methods used to protect copper pipes:
1 A plastic sheath set into the floor with cement mortar. No joints should be located in the sleeve.
2 Burying - Pipes which have been protected laid on top of base concrete and covered by a screed. Pipes up to 28mm may be buried and a minimum cover of 20mm must be applied. When pipes are to be buried in magnesium-oxy-chloride cement or magnesite flooring copper is the only material recommended (BS6891) and must be factory plastic coated.
3 Use of preformed ducts.
4 Use of a protective covering at least 5mm thick (BS 6891).
Copper pipes passing through solid floors must take the shortest practicable route and be enclosed in a gas tight sleeve which is normally another piece of copper tube.
It must be emphasised that copper is the best choice for gas pipes enclosed in solid floors because of its flexibility, strength and good corrosion resistance. BS 6891 does NOT ALLOW stainless steel pipes to be buried in solid floors.
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It's possible that the OP's pipe is covered by 2 above, although it seems to be a grey area.
As I see it I have two choices; one of which may be precluded by future events:
[1] I cut off the supply to the heater and use this as a good reason to install my second Kickspace heater! This will please the cats and dismay SWTSMBO.
[2] The weak cement backfill allows for ready access to the pipe and is therefore 'acceptible'. So I continue to use the heater safe in the knowledge that I can easily get to the pipe. However, as part of the Grand Kitchen Plan the nasty, unfixed and readily ripped up, imitation wood laminate floor (over the gas pipe trench) is to be replaced with slate floor tiles which, I hope, will be totally resistant to removal - ever!! Sounds as though I should cut it off in it's prime just to be sure.
Question: the main gas supply runs through the floor screed. Is that, being steel pipe (gas barrel?) a whole different ball game?
I got the impression it would not conform to the best of recommendations, but nonetheless lots of gas pipes are bedded direct into mortar, and the number of incidents resulting seems to be very close to zero.
Perspective seems to be the real question, in my mind.
In law this is not acceptable for gas pipework must be protected either by wrapping in suitable tape or enclosing in some sort of pipe or duct, if laid in concrete.
Pragmatically, if you pressure test your system and ensure that it isn't leaking you're safe to continue using it ... for as long as it continues not to leak.
Sounds like a very good plan, and kindof what I was trying to get across in my earlier post.
To put this all in context I recently got called to a house where there was a smell of gas which was leaking from copper pipework buried in the solid concrete floors. The floors had been tiled. It made a bit of a mess fixing that lot!
I have also come across copper pipe laid in a screed which were so corroded they more or less came away when you touched them. (Not gas pipework in this case, fortunately.)
Not really: BS6891 says that steel as well as copper should be protected. """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" A gas pipe of pipe fitting shall not be installed in a position where it is likely to be exposed to a corrosive environment. Gas pipes or fittings that are considered to be at risk shall either be manufactured from materials that are inherently resistant to corrosion or shall be protected against corrosion. """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" Rightly or wrongly I wouldn't be as concerned about the steel pipework though.
1) The corrosion requires that the pipes are also damp.
2) When the pipe leaks people will notice the smell.
3) Even a large leak _probably_ can't build up to the 5% required for an explosion if the leak is into an open room.
All the above however is not a cause for complacency. Gas explosions appear to be on the increase. Because the smell of gas is so important to discovering potentially large leaks small leaks have to be fixed.
My house has 3/4 iron gas pipes buried in the screed, as most 60's and
70's modern houses did. Where it ran under the back boiler (now removed) a long-term leak from the boiler had caused a lot of surface corrosion.
I thought the main problem with burying copper in solid floors is the possibility of banging a nail through it. What does BS???? Say about mechanical protection of buried copper gas pipe ??.
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