Safety/reliability of gas isolation valves

MJN · 18 Oct 2021

We want to retire a gas hob (now have induction in a new kitchen in a different room) and so want to get the branch pipe that supplies it capped off. However, we're not quite ready to get that done and so ideally would like to remove the hob and - if safe to do so - have it temporarily isolated by means of the isolation valves that supply it to allow removal of the hob and worktop. There are two valves in series:

I am conscious that water isolation valves often don't perform well, particularly if they haven't been touched for a long time (these must've been here 14 years now). Is it the same with gas valves and, in any case, should they be viewed as nothing more than short term temporary closure e.g. 'back on within a day' type of thing which is not really what's being intended here?

ianmcd · 18 Oct 2021

nope you cant do that, very much against gas regulations

MJN · 18 Oct 2021

Okay, nice and clear - thanks!

tell80 · 19 Oct 2021

when the hob is removed by a RGI then at least have the 1/2"supply cut and solder-capped just after the old fan valve. but best to have the line cut and capped at wherever it branches from the main gas. try not to have redundant live lines except to any cooker bayonet fitting.

MJN · 19 Oct 2021

tell80 said:
when the hob is removed by a RGI then at least have the 1/2"supply cut and solder-capped just after the old fan valve. but best to have the line cut and capped at wherever it branches from the main gas. try not to have redundant live lines except to any cooker bayonet fitting.

Oh absolutely. I've found the branch point and will get it capped back there as I don't want any dead legs hiding in the wall waiting to be drilled into!

MJN · 19 Oct 2021

Here's the branch point:

I thought it looked a bit tight space wise, or is this all par for the course for gas engineers?

ianmcd · 19 Oct 2021

That is not tight , you should see some of what we have to deal with, easy job that one , hardest part will be getting the tape off

MJN · 19 Oct 2021

Thanks Ian, that's good to know. (And I can only imagine what challenges are sometimes put your way!)

Agile · 19 Oct 2021

Your original thought was apparently to just disconnect the hob and turn off both valves!

That is totally against the Gas Regulations!

The ethos is that there must not be an open pipe through which gas can escape and potentially explode ( if someone just happened to turn those taps back on! )

MJN · 19 Oct 2021

Yes, it was only intended to be temporary to allow the removal of the hob, worktop and enable discovery of the branch point. On reflection though that could've taken me a week before I got round to doing everything and I can see now the unacceptable hazard this would've potentially created relying on those valves for complete isolation for that period (although interestingly that's what the hob controls are doing - appreciate the line has got to be drawn somewhere though!). As I've now found the branch, and it being in an accessible position, I'll get a gas engineer to visit first and then I can proceed at leisure with the rest.

MJN · 19 Oct 2021

Incidentally, is there an equivalent of electrical 'safe zones' that apply to gas pipe routing?

MJN · 26 Oct 2021

All sorted now. Thanks everyone for the input.

CBW · 26 Oct 2021

Is the other end being removed? Or had it been capped?

MJN · 26 Oct 2021

He crimped the end you can see (hard to make out in the photo looking at it now) and the other end is still attached to the hob which I'll be removing soon. I don't intend on removing the redundant pipe from behind the plasterboard as it'll just result in a whole load of making good for little benefit (other than avoiding a potential fright if anyone should drill into it at a later date of course!). Instead I'll just cut the pipe back to behind the plasterboard and repair the hole. I asked whether I should cap the other end but he said it wouldn't be necessary and that the residual gas (or rather the smell of the mercaptan) would dissipate soon enough. Is that right or is there something more behind your question?

CBW · 26 Oct 2021

I was told it needed to be capped, as the smell can linger, and give a false smell of gas scenario.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Safety/reliability of gas isolation valves

Similar threads