Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.

On 23 Dec, 16:47, DavidM wrote:
Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.

http://news.bbc.co.uk/1/hi/england/london/8427734.stm says "water from
a burst main got into the gas pipes, cutting off the flow" which
sounds a bit strange. The only explanations I can think of are (a)
Murphy struck and the gas main was broken by the digger repairing the
water main, or (b) the water washed away clay which had been plugging
long-undetected leaks. The latter might have revealed a need to
replace a long length ancient pipe to be safe.

On Wed, 23 Dec 2009 08:19:30 -0800 (PST),
wrote:

On 23 Dec, 16:47, DavidM wrote:
Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.

http://news.bbc.co.uk/1/hi/england/london/8427734.stm says "water from
a burst main got into the gas pipes, cutting off the flow" which
sounds a bit strange. The only explanations I can think of are (a)
Murphy struck and the gas main was broken by the digger repairing the
water main, or (b) the water washed away clay which had been plugging
long-undetected leaks. The latter might have revealed a need to
replace a long length ancient pipe to be safe.

So they use Murphy Construction to do pipe repairs - interesting
coincidence

Even an emergency/temporary replacement of 50m of pipe shouldn't take
days ffs, unless they're gonna dig a trench with teaspoons! But then
they don't seem to care fu about their customers these days

"DavidM" wrote in message
...
Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.



The fixing of the gas pipes isn't the bit that takes the time, a few hours
at most.
Excavation, repair, reinstatement. The main will have been turned off at
the nearest Pressure Reduction Station, (PRS) to facillitate repair.

This will be the bit that escapes you:
Not high-tech but complex.
When gas mains fail the pressure over the entire district supplied will
fall dramatically and with the deliberate isolation of said main there won't
be many millibars around.
Before pressure can be restored the district affected has to be clearly
defined. Every house that has a gas supply has to be identified and
visited. If N/A, revisited etc. If people are away, lots are, or the
property vacant then it has to be isolated, and if the meter is not external
then the service has to be cut off by excavating it first. The reason for
all of this is that some people still have gas appliances with non-cut off
pilot lights. If pressure was restored to such appliances, uncontrolled gas
would fill the property. Missing even a single property is not allowed.

Gas and air must not be allowed to mix within the gas pipes or houses will
be going bang all over the place. So if air has got into the pipes then a
nitrogen purge is necessary to flush it out first, then the nitrogen
flushed out with gas.

So once pressure has been restored with gas only in the mains then every
house service has to be purged to get rid of any air nitrogen.

It is more complex than a water or electric main failing.


mark

"DavidM" wrote in message
...
On Wed, 23 Dec 2009 08:19:30 -0800 (PST),
wrote:

On 23 Dec, 16:47, DavidM wrote:
Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.

http://news.bbc.co.uk/1/hi/england/london/8427734.stm says "water from
a burst main got into the gas pipes, cutting off the flow" which
sounds a bit strange. The only explanations I can think of are (a)
Murphy struck and the gas main was broken by the digger repairing the
water main, or (b) the water washed away clay which had been plugging
long-undetected leaks. The latter might have revealed a need to
replace a long length ancient pipe to be safe.

So they use Murphy Construction to do pipe repairs - interesting
coincidence

Even an emergency/temporary replacement of 50m of pipe shouldn't take
days ffs, unless they're gonna dig a trench with teaspoons! But then
they don't seem to care fu about their customers these days

You are not a customer of those responsible for the gas mains :-)

mark

On Wed, 23 Dec 2009 16:36:17 -0000, "mark"
wrote:

"DavidM" wrote in message
.. .
Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.



The fixing of the gas pipes isn't the bit that takes the time, a few hours
at most.
Excavation, repair, reinstatement. The main will have been turned off at
the nearest Pressure Reduction Station, (PRS) to facillitate repair.

This will be the bit that escapes you:
Not high-tech but complex.
When gas mains fail the pressure over the entire district supplied will
fall dramatically and with the deliberate isolation of said main there won't
be many millibars around.
Before pressure can be restored the district affected has to be clearly
defined. Every house that has a gas supply has to be identified and
visited. If N/A, revisited etc. If people are away, lots are, or the
property vacant then it has to be isolated, and if the meter is not external
then the service has to be cut off by excavating it first. The reason for
all of this is that some people still have gas appliances with non-cut off
pilot lights. If pressure was restored to such appliances, uncontrolled gas
would fill the property. Missing even a single property is not allowed.

Gas and air must not be allowed to mix within the gas pipes or houses will
be going bang all over the place. So if air has got into the pipes then a
nitrogen purge is necessary to flush it out first, then the nitrogen
flushed out with gas.

So once pressure has been restored with gas only in the mains then every
house service has to be purged to get rid of any air nitrogen.

It is more complex than a water or electric main failing.


mark

blimey, tis indeed quite a palaver!
"I know more now than I did before"
Thanks, Mark.

"DavidM" wrote in message
...
On Wed, 23 Dec 2009 16:36:17 -0000, "mark"
wrote:

"DavidM" wrote in message
. ..
Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.




So once pressure has been restored with gas only in the mains then every
house service has to be purged to get rid of any air nitrogen.

It is more complex than a water or electric main failing.


mark

blimey, tis indeed quite a palaver!
"I know more now than I did before"
Thanks, Mark.

Ive just googled the incidents you mention.
http://www.nationalgrid.com/uk/Media...PressReleases/

I notice their plea for minimal electric use. Fat chance! Everyone will have
their electic heats/cookers on full to keep warm and next up will be the
electric system failing.

Looks like it is going to cost a fortune!
It gives them something to do in the freezing conditions.

mark

"mark" wrote in message
...

"DavidM" wrote in message
...
On Wed, 23 Dec 2009 16:36:17 -0000, "mark"
wrote:

"DavidM" wrote in message
...
Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.




So once pressure has been restored with gas only in the mains then every
house service has to be purged to get rid of any air nitrogen.

It is more complex than a water or electric main failing.


mark

blimey, tis indeed quite a palaver!
"I know more now than I did before"
Thanks, Mark.

Ive just googled the incidents you mention.
http://www.nationalgrid.com/uk/Media...PressReleases/

I notice their plea for minimal electric use. Fat chance! Everyone will
have their electic heats/cookers on full to keep warm and next up will be
the electric system failing.

Looks like it is going to cost a fortune!
It gives them something to do in the freezing conditions.

mark


The electrics have failed

http://news.bbc.co.uk/1/hi/england/london/8427734.stm


Adam

On Wed, 23 Dec 2009 17:18:14 -0000, mark wrote:

I notice their plea for minimal electric use. Fat chance! Everyone will
have their electic heats/cookers on full to keep warm and next up will
be the electric system failing.

You mean like part of Maryport last week:

http://news.bbc.co.uk/1/hi/england/cumbria/8420446.stm

--
Cheers
Dave.

mark used his keyboard to write :
So once pressure has been restored with gas only in the mains then every
house service has to be purged to get rid of any air nitrogen.

It is more complex than a water or electric main failing.

I do appreciate a good explanation and that was a good one.

Thanks Mark ^^

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In article o.uk,
"Dave Liquorice" writes:
On Wed, 23 Dec 2009 17:18:14 -0000, mark wrote:

I notice their plea for minimal electric use. Fat chance! Everyone will
have their electic heats/cookers on full to keep warm and next up will
be the electric system failing.

You mean like part of Maryport last week:

http://news.bbc.co.uk/1/hi/england/cumbria/8420446.stm

I recall exactly the same happening in Luton many years back.
Gas company handed out electric heaters, everyone went home and
plugged them in, substation burned out. No gas or electric for
many days.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 23 Dec, 16:36, "mark" wrote:
"DavidM" wrote in message

...

Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.

The fixing of the gas pipes isn't the bit that takes the time, a few hours
at most.
Excavation, repair, reinstatement. *The main will have been turned off at
the nearest Pressure Reduction Station, (PRS) to facillitate repair.

This will be the bit that escapes you:
Not high-tech but complex.
When gas mains fail *the pressure over the entire district *supplied will
fall dramatically and with the deliberate isolation of said main there won't
be many millibars around.
Before pressure can be restored the district affected has to be clearly
defined. Every house that has a gas supply has to be identified and
visited. If *N/A, revisited etc. If people are away, lots are, or the
property vacant then it has to be isolated, and if the meter is not external
then the service has to be cut off by excavating it first. *The reason for
all of this is that some people still have gas appliances with non-cut off
pilot lights. If *pressure was restored to such appliances, uncontrolled gas
would fill the property. Missing even a single property is not allowed.

Gas and air must not be allowed to mix within the gas pipes or houses will
be going bang all over the place. So if air has got into the pipes then a
nitrogen purge *is necessary to flush it out first, then the nitrogen
flushed out with gas.

So once pressure has been restored with gas only in the mains then every
house service has to be purged to get rid of any air nitrogen.

It is more complex than a water or electric main failing.

mark

When a major main replacement program was undertaken in Grimsby/
Cleethorpes a few years ago temporary overground yellow plastic pipe
links were provided while sections were dug up and renewed. The
overground temporary pipes were undersized! It caused havoc at one
school site which the company I was working for at the time had
serviced the boilers prior to the works. We got called every morning
to boilers with blown gas burners failing to light.
I went in early one morning and put a manometer on the supply before
the boilers tried to start. When the boilers were supposed to start
the pressure in the main was only 5millibar so of course the ignition
failed. By about 09.30 the pressure was back up around 21mB and
boilers operated normally but when the canteen kitchen started to
operate the pressure fell to around 15mB and boiler ignition became
erratic although heat was produced if the boilers were reset a couple
of times.
A couple of weeks later the relevant section of main was completed and
the boiler problem went away.

In message , mark
writes

"DavidM" wrote in message
.. .
On Wed, 23 Dec 2009 16:36:17 -0000, "mark"
wrote:

"DavidM" wrote in message
...
Been reading the Eurostar thread with interest.

Similar question then ocurred about the failure of gas supplies in
Luton and Barnet. Why the hell do they think it will take until after
christmas to sort out a couple of broken pipes? Maybe there's some bit
of high tech complexity in gas pipes that escapes me.




So once pressure has been restored with gas only in the mains then every
house service has to be purged to get rid of any air nitrogen.

It is more complex than a water or electric main failing.


mark

blimey, tis indeed quite a palaver!
"I know more now than I did before"
Thanks, Mark.

Ive just googled the incidents you mention.
http://www.nationalgrid.com/uk/Media...PressReleases/

I notice their plea for minimal electric use. Fat chance! Everyone will have
their electic heats/cookers on full to keep warm and next up will be the
electric system failing.

As it seems to have done

now no gas or electricity


Looks like it is going to cost a fortune!
It gives them something to do in the freezing conditions.

mark





--
geoff

On Dec 24, 5:36 am, "mark" wrote:

Every house that has a gas supply has to be identified and
visited. If N/A, revisited etc. If people are away, lots are, or the
property vacant then it has to be isolated, and if the meter is not external
then the service has to be cut off by excavating it first. The reason for
all of this is that some people still have gas appliances with non-cut off
pilot lights. If pressure was restored to such appliances, uncontrolled gas
would fill the property. Missing even a single property is not allowed.

"non-cut off pilot lights" - that sounds very dangerous.
Yet another reason why I won't have gas anywhere near the house.
There have been three emergencies with my neighbours' gas supplies.
I have an amusing video of workmen trying to seal a broken pipe.

In article ,
Matty F writes:
On Dec 24, 5:36 am, "mark" wrote:

Every house that has a gas supply has to be identified and
visited. If N/A, revisited etc. If people are away, lots are, or the
property vacant then it has to be isolated, and if the meter is not external
then the service has to be cut off by excavating it first. The reason for
all of this is that some people still have gas appliances with non-cut off
pilot lights. If pressure was restored to such appliances, uncontrolled gas
would fill the property. Missing even a single property is not allowed.

"non-cut off pilot lights" - that sounds very dangerous.
Yet another reason why I won't have gas anywhere near the house.
There have been three emergencies with my neighbours' gas supplies.
I have an amusing video of workmen trying to seal a broken pipe.

The amount that comes out of an unlit pilot light doesn't pose
much risk of anything.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Matty F wrote:
On Dec 24, 5:36 am, "mark" wrote:

Every house that has a gas supply has to be identified and
visited. If N/A, revisited etc. If people are away, lots are, or the
property vacant then it has to be isolated, and if the meter is not
external then the service has to be cut off by excavating it first.
The reason for all of this is that some people still have gas
appliances with non-cut off pilot lights. If pressure was restored
to such appliances, uncontrolled gas would fill the property.
Missing even a single property is not allowed.

"non-cut off pilot lights" - that sounds very dangerous.

I can only recall seeing these on *very* old cookers. I doubt that many are
left at all but I suppose it's a chance that the gas company aren't prepared
to take yet.

Yet another reason why I won't have gas anywhere near the house.

That's a bit extreme. Properly handled, it's acceptably safe and offers
considerable savings for heating.

There have been three emergencies with my neighbours' gas supplies.
I have an amusing video of workmen trying to seal a broken pipe.

Are we talking about LPG/Propane here? Going to share your video? ;-)

Tim

"Andrew Gabriel" wrote in message
...
In article
,
Matty F writes:
On Dec 24, 5:36 am, "mark" wrote:

Every house that has a gas supply has to be identified and
visited. If N/A, revisited etc. If people are away, lots are, or the
property vacant then it has to be isolated, and if the meter is not
external
then the service has to be cut off by excavating it first. The reason
for
all of this is that some people still have gas appliances with non-cut
off
pilot lights. If pressure was restored to such appliances, uncontrolled
gas
would fill the property. Missing even a single property is not allowed.

"non-cut off pilot lights" - that sounds very dangerous.
Yet another reason why I won't have gas anywhere near the house.
There have been three emergencies with my neighbours' gas supplies.
I have an amusing video of workmen trying to seal a broken pipe.

The amount that comes out of an unlit pilot light doesn't pose
much risk of anything.



not even after a few days in a small kitchen?
mark

On 24 Dec, 11:55, "mark" wrote:
"Andrew Gabriel" wrote in message

...





In article
,
Matty F writes:
On Dec 24, 5:36 am, "mark" wrote:

Every house that has a gas supply has to be identified and
visited. If *N/A, revisited etc. If people are away, lots are, or the
property vacant then it has to be isolated, and if the meter is not
external
then the service has to be cut off by excavating it first. *The reason
for
all of this is that some people still have gas appliances with non-cut
off
pilot lights. If *pressure was restored to such appliances, uncontrolled
gas
would fill the property. Missing even a single property is not allowed.

"non-cut off pilot lights" - that sounds very dangerous.
Yet another reason why I won't have gas anywhere near the house.
There have been three emergencies with my neighbours' gas supplies.
I have an amusing video of workmen trying to seal a broken pipe.

The amount that comes out of an unlit pilot light doesn't pose
much risk of anything.

not even after a few days in a small kitchen?
mark- Hide quoted text -

- Show quoted text -

Sufficient natural air changes to avoid the concentration of gas in
air reaching ignitable or explosive levels

In message
,
cynic writes
"non-cut off pilot lights" - that sounds very dangerous.
Yet another reason why I won't have gas anywhere near the house.
There have been three emergencies with my neighbours' gas supplies.
I have an amusing video of workmen trying to seal a broken pipe.

The amount that comes out of an unlit pilot light doesn't pose
much risk of anything.

not even after a few days in a small kitchen?
mark- Hide quoted text -

- Show quoted text -

Sufficient natural air changes to avoid the concentration of gas in
air reaching ignitable or explosive levels

8% in round figures


--
geoff

On Dec 24, 7:08*am, Matty F wrote:
On Dec 24, 5:36 am, "mark" wrote:
*The reason for all of this is that some people still
have gas appliances with non-cut off pilot lights.

Non-cut off gas fires too.
Which are a lot bigger - 6kW input bigger for example :-)

"non-cut off pilot lights" - that sounds very dangerous.
Yet another reason why I won't have gas anywhere near the house.
There have been three emergencies with my neighbours' gas supplies.
I have an amusing video of workmen trying to seal a broken pipe.

Natural Gas is a) lighter than air b) very smelly due to additives.
You can get auto-cutoff valves if there is a full-bore escape
(vandalism of an outdoor pipe after the meter, BES do them - about £40
well spent if drugged up copper thieves in your area).

LPG is a different matter a) heavier than air b) smell doesn't reach
your nose, but can pool underfloors (basement, wooden ground floors)
until it finds an ignition source such as a low level socket or low
level socket timer and kaboom.

As to sealing a broken pipe, I suspect they use an "inflatable bulb"
which expands into the pipe sealing it off (the pressure is 75mbar
however the flow can be staggering if a large bore gas main). If it is
cast iron then just wrap in a self-amalgamating wrap of some sort.
When my mothers cast iron supply pipe was leaking the "apprentice"
thought he had found it and then slammed his spade right through it,
the Transco ACS at the time said "oh yeah, he's found it, clumsy sod".
The apprentice is now working in the nuclear recycling industry
now :-) Nice new yellow alkathene stuffed through.

On Dec 24, 9:37 pm, "Tim" wrote:
Matty F wrote:

Yet another reason why I won't have gas anywhere near the house.

That's a bit extreme. Properly handled, it's acceptably safe and offers
considerable savings for heating.

That may well be true in the UK. But here in NZ I don't need heating
(or cooling). I probably turned the heater on less than 10 times in
the last year. The supply charge for gas (even if I don't use any at
all) would cost more than my entire heating bill.
If I have gas water heating, the electric power company has nothing
they can turn off at peak times, so they will charge a higher rate for
all of my power.

There have been three emergencies with my neighbours' gas supplies.
I have an amusing video of workmen trying to seal a broken pipe.

Are we talking about LPG/Propane here? Going to share your video? ;-)

The video is somewhere on a backup CD somewhere.
The pipe was plastic. To seal it they just bent it in half and put
some duct tape around it.

"Matty F" wrote in message
...
On Dec 24, 9:37 pm, "Tim" wrote:
Matty F wrote:

Yet another reason why I won't have gas anywhere near the house.

That's a bit extreme. Properly handled, it's acceptably safe and offers
considerable savings for heating.

That may well be true in the UK. But here in NZ I don't need heating
(or cooling). I probably turned the heater on less than 10 times in
the last year. The supply charge for gas (even if I don't use any at
all) would cost more than my entire heating bill.

Well that's a cost issue, not a safety one.You were saying it was too
dangerous (which you've snipped).

Tim

On Dec 28, 4:15 am, "Tim Downie"
wrote:
"Matty F" wrote in message

...

On Dec 24, 9:37 pm, "Tim" wrote:
Matty F wrote:

Yet another reason why I won't have gas anywhere near the house.

That's a bit extreme. Properly handled, it's acceptably safe and offers
considerable savings for heating.

That may well be true in the UK. But here in NZ I don't need heating
(or cooling). I probably turned the heater on less than 10 times in
the last year. The supply charge for gas (even if I don't use any at
all) would cost more than my entire heating bill.

Well that's a cost issue, not a safety one.You were saying it was too
dangerous (which you've snipped).

I said (which you've snipped):
There have been three emergencies with my neighbours' gas supplies.

Three occasions when a pipe has broken, causing a huge amount of gas
in the air and all the neighbours to phone the fire brigade at the
same time. That could have been dangerous if there was a spark
anywhere.