speculation about cut gas pipes

[RayCaister]

This incident is now a police inquiry. The gas pipe was cut inside a property. ... https://www.bbc.co.uk/news/uk-england-lancashire-57232373

 

[Captain Nemesis]

Should we speculate that because its a police inquiry its looking like a cut before the meter so as to steal gas rather than the HSE investigating desperately incompetent unregistered gas work?

 

[Mottie]

Should we speculate that because its a police inquiry its looking like a cut before the meter so as to steal gas rather than the HSE investigating desperately incompetent unregistered gas work?

Ok. Let’s put the tragedy aside for a moment. Let’s speculate why a gas pipe anywhere would be cut before the meter. You first.

 

[Captain Nemesis]

Just thinking that if someone wanted to steal gas theyd have to divert some or all of it from the pipe before it went through the meter.

 

[boolie]

Just thinking that if someone wanted to steal gas theyd have to divert some or all of it from the pipe before it went through the meter.

a little bit off topic.. but Ive always wondered why the whole underground gas pipe doesn't also blow up. So, why doesn't the fire go into the underground pipes and theoretically blow up the whole of the gas grid?

 

[Captain Nemesis]

Gas on its own does not burn - needs oxygen.

 

[boolie]

thinking about it.. it must have some safety valves built into the gas network.. a bit like a blow torch. So just because you ignite the blow torch doesn't mean the canisters gonna explode

or what @Captain Nemesis said!

 

[Stivino]

Ok. Let’s put the tragedy aside for a moment. Let’s speculate why a gas pipe anywhere would be cut before the meter. You first.

£££'s?

 

[Stivino]

a little bit off topic.. but Ive always wondered why the whole underground gas pipe doesn't also blow up. So, why doesn't the fire go into the underground pipes and theoretically blow up the whole of the gas grid?

I think, it can only burn in the presence of oxygen, i.e. at the end of the pipe. Once it's burning, it can no longer explode, maybe?
Q.E.D.

 

[Mottie]

I can remember that experiment in chemistry in school. The teacher showed us why you needed oxygen to to burn things. Get an empty tin can, put a hole in the top, fill it with gas from the Bunsen burner, turn it upside down leaving a room for air to enter the bottom, set light to the gas rising from the hole. It would burn slowly like a candle until the right amount of air had been sucked into the can and them.....boom! The contents of the can explodes and the can flys up in the air.

 

[boolie]

Gas on its own does not burn - needs oxygen.

that's interesting... so hypothetically say you cut into the mains gas pipe in your house and gas starts escaping - then you immediately ignite it with a match.
Is all that's gonna happen is that it will be like a giant blow torch? (a bit like a flame thrower)

 

[Harry Bloomfield]

that's interesting... so hypothetically say you cut into the mains gas pipe in your house and gas starts escaping - then you immediately ignite it with a match.
Is all that's gonna happen is that it will be like a giant blow torch? (a bit like a flame thrower)

You get an explosion when a lot of gas is mixed with a lot of air, in approximately the right proportions, in a confined space. If that confined space is a room, the room explodes violently once ignited.

The gas to air needs to be roughly between 5 and 15% gas, for it to explode.

As you turn a gas fire or gas hob burner, you often hear a pop - that is the remains of the gas burning back from the burner, to the gas control knob.

 

[bernardgreen]

Is all that's gonna happen is that it will be like a giant blow torch? (a bit like a flame thrower)

Yes... that is what will happen.

 

[dilalio]

that's interesting... so hypothetically say you cut into the mains gas pipe in your house and gas starts escaping - then you immediately ignite it with a match.
Is all that's gonna happen is that it will be like a giant blow torch? (a bit like a flame thrower)

What do you think happens at the burner on a gas hob? Or a flare on an offshore gas rig, if you want a bigger example.

 

[fixitflav]

thinking about it.. it must have some safety valves built into the gas network.. a bit like a blow torch. So just because you ignite the blow torch doesn't mean the canisters gonna explode or what @Captain Nemesis said!

It doesn't need safety valves. As the Captain said, it needs oxygen to explode. Lower and upper explosive limits, LEL and UEL (in air) are about 3% and 15%.