Blocked gas pipe

[Dannypipe]

I've got a customer with a blocked gas pipe.

He's had transco out twice, and they've confirmed it. I've traced the run (half of which is buried under his patio).

Its not undersized but when the put the hob on and the boiler kicks in the flame on the hob almost goes out.

I haven't checked WP at the appliances but checked it at the meter and it's all OK.

So anyway, I disconnected the boiler and hob, and put lever iso's on the pipe work. Disconnected at the meter, and rigged up the compressor. Gave it all a good blow out. (Gave it 8 bar dynamic pressure, as I was getting no crap out at lower pressures.

Nothing major came out. But there was something in the air, as we were all coughing! I said to the customer, I doubted it would make much difference as I didn't blow anything substantial out. Then attached everything again and voila the problem was gone.

That lasted two days, got a call today the problem is back.

Customer reckons the main gas main is probably ancient, so could be rust particles blocking it I guess. Anyone come across this? Any ideas to throw around?

 

[Killy Bing]

Is it steel or iron?

blow from both sides?

could be a flake flapping up and down?

 

[Dotty]

Blast her out again and stick a Y strainer in at the meter, that way if you catch anything you've evidence to have a pop at transco.

 

[Dannypipe]

It's copper from the meter. Can't remember what comes out the ground to the meter think it was copper too but it must convert to steel at done point I'm sure.

Good shout with the strainer and to blast in both directions. Only went the one way before. Into the property. Frustrating one. Thanks chaps.

 

[Dannypipe]

Like I said there is a bit of a run under the patio that I assume us 28mm copper but that could be inch barrel for all I know.

 

[Killy Bing]

Hmm, think you can push a mouse/cable down it? Or you could invest in one of these laptop 15mextension cams?

 

[Ermintrude]

It will be cornflakes . Fill service with water put FB ISo on end with vent to atmosphere . Close ISo charge with water to about 4 bar then open ISo. Should get lots out. Doubt you will clear it muck sits In Low spots. Also just shake meter upside down onto white paper and vent ecv onto some kitchen roll .

 

[mfgs]

I haven't had a blocked pipe, but I have had it where grey flakey stuff was building up on the walls of the copper and were flaking off and blocking the gas valve on a boiler. I fitted a filter from BES on the supply to stop it clogging to valve again.

 

[Dotty]

You wouldn't have got decent pressure after the first time you blasted it.

 

[Dotty]

[DLMURL="http://www.ciphe.org.uk/Professional/Public-Health/Black-Dust/"]Black Dust - CIPHE[/DLMURL]

 

[arran197]

I've had a blocked gas valve using Stoke a few times. Not why, but had lots of flaky grey stuff put of 2 sigma valves.

 

[albatross]

Have you been there when it has done it?
You need to be doing working pressures at appliances and meter in fault conditions.
To me it sounds more like an intermittently sticking meter or governor.

 

[Ermintrude]

Had a few like this over last few years. It appears like faulty gov, but if you check meter it's giving 21 and boiler 12. Normally in full chatt on DHW

 

[Dannypipe]

Cheers for all the comments. Customer has had supplier out twice and and so governor must have been checked? Not been there when they've come. I checked working pressure at meter and it was fine but I take your point. I have one of those ended scope cameras. It won't get round the first bend Billy!

Customer asked me if I could fit a filter on it after the meter. I said no. Didn't think it would be allowed. Said he has one on the gas valve to boiler but not on the hob. Seems I was wrong.

Took the meter off when I blasted it last time. It looked clean but I will be more thorough this time. It certainly could be collapses under the patio. That's a very good point.

 

[Dannypipe]

*endescope (on phone).