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> they would routinely encounter gas lines, cut them WITHOUT turning off the gas, and keep working That's still done today, evidently! A few months back, there

> they would routinely encounter gas lines, cut them WITHOUT turning off the gas, and keep working That's still done today, evidently! A few months back, there was a small gas leak in my neighborhood. When they knocked on my door to say they'd be working in the area, the repair crew leader was kind enough to indulge my questions. I asked them if my gas would be shut off. They said no, they do the work while the gas is still on! And they must have been cutting into the gas line because they replaced a section that ran under the street. They used a backhoe to dig huge holes on both sides of the street and then fed a flexible pipe through. Here's a video about something kind of similar: https://www.youtube.com/watch?v=UCMs__ZnOfA https://www.youtube.com/watch?v=UCMs__ZnOfA I'm sure today's techniques are different and much safer, so I don't think it negates your point that they used to do risky stuff.

lostapathy 3y ago
> I asked them if my gas would be shut off. They said no, they do the work while the gas is still on! My understanding is that most "last mile" gas lines are pretty low pressure and low flow. On purpose, so that if theirs a leak they aren't releasing massive amounts of gas into the atmosphere in a hurry, so the concentration doesn't raise to dangerous levels. Then when they are working on the lines and in those pits to make connections, they have detectors to tell if there's a dangerous build up, and ventilation to ensure it doesn't happen anyway. The system generally being low pressure is why sometimes during really cold periods when demand is high, the gas company has to adjust field regulators to increase flow so that demand can be met. They normally run at low enough flow that if everyone's furnace and stove and water heater all run at once, the lines would effectively run out of gas.
- Doxin 3y ago
  For some anecdotal comparison on the pressure on the main lines on the other hand: Recently a gas main near me sprung a leak. It sounded like a low flying jumbo jet right overhead while I was over a kilometer away. The pressure on those must be absolutely bonkers.

lostapathy 3y ago

> I asked them if my gas would be shut off. They said no, they do the work while the gas is still on! My understanding is that most "last mile" gas lines are pretty low pressure and low flow. On purpose, so that if theirs a leak they aren't releasing massive amounts of gas into the atmosphere in a hurry, so the concentration doesn't raise to dangerous levels. Then when they are working on the lines and in those pits to make connections, they have detectors to tell if there's a dangerous build up, and ventilation to ensure it doesn't happen anyway. The system generally being low pressure is why sometimes during really cold periods when demand is high, the gas company has to adjust field regulators to increase flow so that demand can be met. They normally run at low enough flow that if everyone's furnace and stove and water heater all run at once, the lines would effectively run out of gas.

Doxin 3y ago
For some anecdotal comparison on the pressure on the main lines on the other hand: Recently a gas main near me sprung a leak. It sounded like a low flying jumbo jet right overhead while I was over a kilometer away. The pressure on those must be absolutely bonkers.