Very general question about working on gas pipes...

[Pete E]

A while before Christmas, we ended up needing the gas pipe feeding our gas hob moving a couple of inches to allow a new oven to slide in properly underneath..

I managed to find a local Gas Safe plumber to come out and do the job for a reasonable price. He explained in general terms what he proposed, and I left him to get on with it as I was working myself.

I know he ended up cutting and soldering a new bit of pipe on the gas supply, but I was wondering how you guys do that safely given your dealing with gas?

Do the pipes need purging before starting? As someone who has happily soldered normal 15mm & 22mm water pipes in the past, I have been curious about this for a while...

I have no intension of touching anything to do with gas, and this is just a very general question, so not looking for a "detailed how"...

Regards,

Peter

 

[steadyon]

Pipes should be purged of gas at start. Its not a major job in a domestic setting. Gas pipes should be purged of air before relighting, again not a major job domestically.

 

[Pete E]

Pipes should be purged of gas at start. Its not a major job in a domestic setting. Gas pipes should be purged of air before relighting, again not a major job domestically.

Thanks for that, much appreciated...I sort of assumed that would be how it was done, but wasn't sure...

In my case, the chap doing the work spent a bit of time going back and forth to the meter cupboard outside so I am guessing that's where he purged from...

 

[John.g]

Purely for interest, on large gas lines it is normal practice to purge with nitrogen before removing/replacing a section of gas line, the new section is then purged with nitrogen before admitting gas, this is to avoid a explosive mixture building up in the gas line. We used portable gas analyzers to check the gas content, these analyzers had two scales, 0 to 100% gas and 0 to 100% LEL (lower explosive limit) You first monitored on the 0 to 100% gas scale and then when the gas content fell to < 5% you changed to the 0 to 100% LEL scale, which is 0 to 100% of 5% and when this fell to 10 to 20%, (0.5% to 1% gas) the line was deemed safe to work on, or admit gas, after admitting gas you then purged with gas until the analyzer read 100% on the 0 to 100% gas scale. Gas has a flammable range of 5% to 15% (in air), it is not flammable if the concentration is below 5% or above 15%.