CH₄ + 2O₂ ⇒

At this point, no one knows for sure, and the investigation might take a year. (My mother-in-law lives 10 miles from the area, and works in one of the towns where the explosions/fires have happened.)

The current theory is that the high-pressure main gas lines were pressurized at much too high a level. Ordinarily, (in other areas, at least) this wouldn't be a problem, but the gas lines in the North Boston area are notoriously poorly maintained and old. The gas and electricity has been shut off, the area evacuated, and all the roads leading in to the area are closed.

To my mind, this is what you get when you allow a for-profit, private company to own and operate what should be a public utility. Yes, when the government runs these things, they are less "efficient" than a private company would be, but at least there's no incentive to make extra profits by neglecting maintenance.

 

My assumption (without a shred of evidence, but it's logical) is either that the lines leading from the over-pressurized gas main were in such bad shape that there was no time to relieve the pressure before things started blowing up, or that Columbia Gas didn't realize the gas main was over-pressured until things started blowing up. Or maybe both.

 

no answers yet, over pressurization is the prevailing theory. not sure how that happens though.

 

Recently hired Flint water employees.

Bob Wilson

 

So you expect a government organization typically chronically starved for funds by the political machine to do better?

Regulated utility with a charter with requirements policed with funds from the profits from the charter might be a better organizational structure. Competed every ten years. Or ????

All you have to do is look at the current story about funds diverted from FEMA to ICE to see how politics intrudes in how government organizations get funded. Or the IRS budget cuts considering that for every dollar of funding their increased enforcement of the tax policies dictated by politics gives back to the treasury many multiples of dollars.

Typed while in the bands of Florence. Safe but thinking of all those in harms way.

 

A friend of ours had to evacuate for this. Luckily, his apartment was not the one exploded. What I don't understand is how over-pressurized gas lines leads to multiple explosions?

 

The overpressure comes out at multiple leak locations, inside numerous customer premises.

 

You make a really good point - sheltering the maintenance function against political greed is critically important. I don't pretend I have great answers to this - I'd be fine with a regulated, chartered, local utility company if it were reliably monitored and the monitors/regulators weren't captured by the utility company. It just turns my stomach to hear that maintenance had been deliberately neglected for years, putting people's lives and property at risk, just so the corporate overlords in Indiana can make a few extra dollars.

I think the enormous size of NiSource is a major part of the problem. How is a company that "serves" 3.5 million natural gas customers across seven states ever going to care about local conditions?

A disaster this size should be a big enough problem to whoever is running the gas system that they work diligently to keep it from ever happening again. But even if they have to pay all the damages in full out of their own pocket (they won't, they have insurance against this sort of thing), NiSource would barely notice the small blip on their balance sheets.

 

A new/properly maintained system will have a safety margin built-in, so leaks won't happen even if there is too much pressure. But old, weak, or corroded pipes, fittings, meters, appliances, etc. will give way at all the weak spots, just like an old garden hose would if you hit it with too much water pressure. Then, once you have enough leaks, all it takes is a stray spark or two, and...

Most utility companies inspect their gas mains and house pipes at least yearly, and replace anything that looks like it's going bad. But this costs money. It looks like Columbia Gas neglected these inspections/replacements in at least 70 locations. Although, to be fair, we don't know just how much the gas main was over-pressurized. If you hook a garden hose to a fire hydrant, for example, even a brand-new hose will start leaking.

 

Why? The fire hydrants here are connected to the very same water supply mains as the house supplies, thus have the very same static pressure.

 

OK, that was a bad example. In my defense, I was trying to give an explanation with things that would be familiar products to everyone.

Let's try this - If you hook a garden hose up to the output of a regular faucet, it sees about 40psi pressure. If you hook a garden hose up to the output of one of the 20hp centrifugal pumps we use here at work, it will be exposed to about 175 psi. At that level of pressure, seals, fastenings, and even the fabric of the hose itself will start to spring leaks.

I think that something similar happened in Lawrence - the gas main was exposed to more pressure than it was able to contain, and that was why there were a great many leaks. There are two possible explanations for the containment failure - either the pipes and fittings, etc. had degraded to the point of not being able to contain a mild over-pressure, or the over-pressure was so extreme that the pipes, which were in good condition, couldn't contain the gas. Verbal evidence from friends and family in the area about frequent other, more limited leaks leads me to think that the first theory is correct, and that the gas company has been neglecting maintenance for a while - but I could be wrong.

 

don't gas lines have pressure reducers before entering a building?

i've seen construction physically pull the lines out, but i think new installations have exterior break off's.

 

But even those have finite limits on how much intake pressure they can handle.

 

blow right through them? i thought they had pressure relief valve?

 

Thanks for the explanations. I never lived in a house with gas line, though I have hoped for having gas service to our house for heat for a long time. I am having a second thought now.

 

The relief valve would blow, releasing gas into the area, where it might still get inside the structure. It should be better than leaks inside though.

This assumes the relief valves themselves were in working condition. They work on hot water tanks to keep them exploding, but not if a leaky one is simply closed off instead of replaced.

 

I've never lived in a home with gas service either. We thought about it at one time, to save on electric heating costs, but the cost to run service to the house was excessive. Much later incentives, when full length trenching was no longer required, enticed two neighbors to spring for it.

But I have moved beyond that to a ductless heat pump, air source, now accompanied by solar PV. Combined with multiple other active and passive energy upgrades, my house is now all-electric with net-zero energy consumption. I.e. my house produces all the energy it needs, though it must remain tied to the electric grid due to the time- and season-shift between production and consumption.

 

the finger pointing has already begun.