If you were responding to my post, you may have misunderstood my question snipped-for-privacy@aol.com...
I was asking about his repair scenario, not the new service line to the customer.
hallerb said "gas companies do it all the time, as proof whens the last time your gas was shut off when they did repairs?"
I am assuming he means that the gas company does not shut off the gas every time they repair a gas line. Here's my question: If they open a line and vent it to the air during the repair, then wouldn't any downstream customers lose pressure and therefore lose their pilot lights? I'm not questioning the fact that they do or don't shut off the gas, but it seems to me that to any customers downstream of the repair, it's going to look like the gas was off if they open the line.
Perhaps they tap around the repair before opening the line? If that's the case, no one would lose service, but they are not really doing the same thing as a guy installing a valve or T in a house like the OP (and I) have seen them do.
OK, yes, I did misread your question and answered the unasked one... :)
If they were, indeed to completely open a line, then yes, unless there were alternate supply there would be a loss of service downstream. IME anything that required that level of work _would_ entail a notification and a cessation of services. Not many residential branches have alternate supply mains although I suppose if the work were extensive enough they might bypass an area to not have extended outage.
In general, installed pipelines are pretty maintenance free for quite long time periods so the consumer observation of loss of service is quite rare. Our tap comes directly off a main (36") cross-country line that crosses our place east of the house about a quarter mile away. To the best of my knowledge that line hasn't had a service outage in
20-something years since they redid a section. It is flown by aerial surveillance once/month to spot any problems. The other line just to the west of the house that was more recently laid was worked on just last year to lower it under the road because the county has been making noises of re-elevating these roads sometime and if they were to do so they just might have come close to the existing depth. It's a 42" line and was shutdown for a period while the new section was fitted in and welded in place. They only dug access holes to the ends on each end about 40-ft away from the road and then a little longer trench on one side. The then punched the new through under the road w/o trenching the
100-ft or so from one access hole to the other. The did a local pressure test on the new section before inserting it then a pressure test on the last connections and done. On those big lines they don't/can't flush them anyway because of the length the amount of air in a 100-ft section out of the 1500 miles before it gets to its ultimate destination is inconsequential as it gets mixed up during the compressor booster stations anyway.
For smaller side distribution lines I don't know whether they would bother to try to purge or not or whether they just let the end users deal with it until the air slug is gone...
When I took some fire science courses years ago, the prof told us that a lit cig won't light gasoline, the end of the cig coats in ash, he said. One guy got complacent about stuffing out his smokes in gasoline, and flicked one. The ash knocked off, and the increased air flow made the glow hotter. That was enough to light the gas that time.
Some pressure regulators will lock out. As for why anyone would shut the gas off, it may be to remove and bypass the meter. People go to great lengths to steal utilities.
Last week we hat the gas off at work while they hooked up an additional gas line. A service guy had to check each appliance in the building to be sure it fired up OK. Of the 10 units, two have pilot lights (others are electronics) and he used a stick match on the end of a 6" rod with a clip to hold the match. For safety reasons, they are not allowed to use the butane lighters. He said they are too explosive and pack the power of 1/4 stick of dynamite.
Someone has a goofy sense of things. Someone want to tell me how a butane lighter can explode while lighting a pilot light?
I use an Aim N Flame, one of the long lighters with the flame at the end. Or, I use a Mapp or propane torch to warm the thermocouple and light the pilot. I've been known to warm the thermocouple with a Mapp torch, turn the gas valve open, and the torch lights the burner ring under the water tank. Yeah, that's probably not a good idea.
I don't much like the smell of sulfur with using matches.
To reset the meter you turn on the gas, open the cap for the diaphragm, and there is a little shaft in there, you just give it a tug and you will hear the gas start flowing, then put the cap back on. No need to call the gas company.
I probably goes with the "don't use your cell phone when pumping gas" stories. I did a quick Google search and found nothing of interest on explosions
Not quite. Flash point is the point at which a liquified gas can produce enough vapor to flash when ignited with a flame. By definition, methane in a home is well above flash - all flammable gasses are above flash point when they're a gas. The issue raised by the OP was the temperature of the ignition point.
The autoignition temperature of methane is 537C. Which theoretically means that methane won't ignite unless it comes in contact with something above 537C.
A few years ago I helped my wife put together a mock safety program for a class she was taking. On the CD we included a video of a lady who answered her cell phone while pumping gas and the "air" around her burst into flames. I'll see if I can find it or the link and get it posted someplace.
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