Gas Regulations

[amos]

I read in Ed Sirret's FAQ that underfloor (underfloorboard?) gas joints should be soldered rather than compression joints. My Q is - is this a regulation or a suggestion. I have to confess this is not a DIY question really - I have pulled up the floorboards to inspect some plumbing (at least it vaguely resembles plumbing!) work some cowboys did for us, and noted incidentally that they used compression joints for the gas under the floorboards. Personally I don't count myself gas competetent (perhaps knowing your limits does count as DIY!). But I guess it might also be useful to some DIYers out there.

More practically - if I leave these as compression joints, am I actually likely to suffer...

Amos

[BigWallop]

Compression fitting move with differing temperature conditions, and this can cause them to release their tight grip on a joint. In areas which are difficult to get to and are hidden, then a good joint which keeps its integrity through different conditions is a properly soldered one. So it is the safety aspect of the hidden pipework that benefits from being done properly, that's unless you can insure that you can check all your compression joints for tightness and soundness regularly.

[Amos]

Thanks. That makes sense. So it sounds like it is not ideal, but is it illegal? Unfortunately the pipes will be going under the floorboards, then some hardboard, then some laminate, so it is indeed not ideal!

Amos

[Ed Sirett]

This requirement taken is from materials based on BS 6891. The regs require things to be done right and than means according to various normative documents of which this is a major one.

It is great pity that normative documents of all sorts are not placed into the public domain.

[Ed Sirett]

Incompetent work is illegal. Compression joints in inaccessible locations are incompetent, because they do not follow the required standard.

[Dave]

Without disagreeing with what you have to say. In the aerospace industry, compression joints are the norm and I have never come across a joint that has failed through movement. Vibration is another story.

Now I only have experience on the plumbing in my own house, but I have never had a compression joint give me any problems in my central heating system. Some of them have been there for over 15 years.

I can't argue with that.

Dave

[<me9]

From my recollections, the veto on compression fittings came about after one incident where an explosion occured where the final connection to the boiler was a compression fitting, wrongly installed something like 15 years previously.

At the time and subsequently, following the ban final connections to boilers etc. were normally compression fittings, so that point of error remained, but their use elsewhere was banned, although they had never proved to be a problem.

IME, however, I much prefer soldered joints, being more reliable, but with the assistance of suitable, supposedly unnecessary extra jointing, I've had no problems with compression fittings.

[Sean]

After reading this tread i'm still not quite sure if compression joints are illegal or not?

I assume they are not as a Brotsh Gas guy recently came to cap off a boiler and used a compression stop end.

Are there seperate standards for water and gas 15mm fittings?

[Ed Sirett]

They are incompetent and therefore illegal if used in inaccessible places. There are acceptable elsewhere.

This was an accessible location hence OK.

Yes but not in the case of compression joints.

Some of them are given in the FAQ. They are mostly about how it goes through the wall.

[Lobster]

For real? When can't you use a compression joint on a water pipe joint? Surely there's a massive difference between the implications of a gas leak vs a water leak?

[BigWallop]

Were these joints used on fluid transmission or gas flow? A joint which stops fluid leaking may just be loose enough to allow gas or vapour to seep out. That's another reason why a leak testing kit, of paste or liquid type, should also be used on soldered joints in gas pipework.

(insert)

[Nick Atty]

Interestingly, they are required on canal boats (at least, they were in the last incarnation of the Boat Safety Scheme - it's hard to keep up with the changes). The argument here is that vibration from the engine will cause soldered joints to fail so only compressions are allowed.

They should, however, be kept to the minimum (so no straight couplings), the pipes supported at regular intervals, and the whole thing be accessible for inspection.

[Doctor Evil]

They are not. Compression (brass fitting with olive) is used at appliances. Compression is "discouraged" on gas supplies, as it encourages cowboys and DIYers to screw up. There was also the fear that compression joints would work loose on suspended floors with the constant walking above.

When installing backboilers the gas pipe inside the chimney breast cannot be soldered, as any fire there may unsolder the joint. Compression is allowed here. but one piece of pipe bent to suit is encouraged. Best to avoid back boilers anyway. A waste of time.

[Ed Sirett]

I took this to mean "Is the fitting _itself_ was made to a different standard." Come to think of if there are some plastic compression fitting not made to BS 864 (?) which would, of course, not be suitable for gas.

[nimbusjunk]

joints that were not very readily accessable were changed

in the case of a hob it seems that you would probably have to use a compression joint

hth phil

[BigWallop]

compression joints that were not very readily accessable were changed

On the final connection to the hob itself, then yes, you would use a compression fitting. The rest of the hidden pipework though, needs to be made with soldered joints. The hob should be in an accessible position, but the pipework supplying it may all be hidden behind cupboards, under floors or buried in walls, which is not to easily accessed.

[Ed Sirett]

compression joints that were not very readily accessable were changed

One of the gas fitting text I have here suggest that 'inaccessible' means under-floors or in ducts.

I would have no qualms about passing a hob supply where the compression joint(s) are accessible by removing drawers.