Major Screwup by Gas Company - House Explodes

[Tom Warner]

The "high pressure" line (reportedly) was 60 psi, the normal street line (which the high pressure was accidentally connected to) pressure is only 2 psi. When I first heard "high pressure" line accidentally hooked up, I thought they were referring to the Tennessee Gas interstate lines that serve the local utility companies in Eastern Massachusetts towns. Those lines have 600-1500 psi in them!!! TN Gas spends a lot of effort maintaining their infrastructure, probably more than Keyspan (the local gas utility).

Several reports have stated that the regulator should have prevented too much pressure in the house even after the pressure mismatch. Is this true? Can the regulator next to the meter reliably regulate when the supply pressure is that high?

Then again I don't think there were any other leaks inside houses on that street other than the one house that was destroyed, so perhaps everyone else's regulators worked ok.

[Greg O]

Many regulators are designed to handle only so much inlet pressure. Over the rated pressure they "lock out", or just slam shut, stopping the gas flow. It is possible that many regulators do not do this, or the diaphragm in the regulator ruptured from the excessive gas pressure, spewing gas out the vent. Greg

[Tom Warner]

Last year, I had Keyspan Energy (the same utility that blew up the Lexington house) replace our regulator. It was making a funny noise whenever the hot water heater was running. It took quite a bit of time before I figured out that this strange noise was ocurring when the hot water heater burner was on, and then that it was actually coming from outside because it sure didn't sound like it was. Keyspan took four or five four-hour service appointments (most of which they never showed up) before they finally got it fixed. Along the way they replaced the gas meter for some reason, but of course that didn't fix the problem. The problem was the regulator was sucking air in through the vent, and the diaphram inside was vibrating as air went past, causing the noise which then resonated through the gas pipes. I've wondered if this air introduced into the gas line would cause the appliances to operate incorrectly

There are also excess flow valves, which shut off the gas if too much gas enters the house at once. The NTSB strongly recommends excess flow valves after a tragic accident that blew up a brand new house and killed a family during their first night in their new house. Unfortunately they usually aren't required for new service and cost a mint to install for existing service, and Keyspan said the customer would have to pay for one if one was available at all. I think the new propane grill tanks have excess flow valves built in.

[George]

In my area most of the street lines are nominal 60 PSI. They install a regulator where the service line rises into the meter saddle.

[mm]

We don't have Keyspan here, but we do have C-Span. It forces Congressional sessions and committee hearings into our houses and must be responsible for almost as many adverse medical incidents as Keyspan.

I think hot air is the pressure source, but I'm not sure what the maximum expected pressure is.

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[mm]

Don't get an electric goat.

Unless you get a GFI.

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[CJT]

I once (long ago) worked for a long haul transmission company. We flew the lines regularly looking for stuff like dead crops that indicated below-surface leaks. Every few years the pilots would spot a farmer with a drill trying to install his own "farm tap." 1500 psi lines, those were, as I recall. Luckily the steel was thick enough that the farmers didn't succeed, or we'd have fewer farmers.

[Tony Hwang]

Hi, Pipe lines carry gas, oil, even coal. you name it. Tony