Pipeline Explosion
Last week we had the Colonial Pipeline cock-up and it got me to thinking. This thing is delivering two and a half million gallons of gasoline a day to the east coast of the USA. 2.5 million gallons every day, day in, day out. I did some calculations. If the pipe is three feet in diameter, the gasoline in the pipe is moving at a rate of about one foot every two seconds. Not very fast. If we cut the hypothetical diameter of the pipe to two feet, the rate doubles to one foot every second. That should work okay, shouldn't it? Well, it there wasn't any drag, it might, but there is, and drag goes up by the square of the speed, so you might be able to get by with a smaller pipe, but the amount of power required for the pumps is going to go up. So we'll stick with a three foot diameter pipe.
A three foot diameter pipe is going to hold a heck of a lot of gasoline. Every mile of pipe is going to hold almost 300,000 gallons which is going to have a mass of 850 tons. It's not moving very fast (6 inches per second, or about one-tenth walking speed), but we have a whole lot of it. At the sending end we will have a pump sucking gasoline out of a tank and at the receiving end we will be dumping the gasoline into another tank. What happens when the receiving tank gets full? We are going to divert the flow to another tank, which means opening a valve to the new tank and closing the one to the full tank.
What happens if we get the order wrong and close the valve to full tank but don't open the valve to the next tank? We've got a zillion tons of gasoline coming down the pipe. I don't think there is pipe fitting in the world that can resist that kind of pressure. The pipe will burst and the area will be flooded with gasoline and with that kind of destruction I wouldn't be surprised if something hot and sparky appeared on the scene and ignited this mess and we got an inferno.
Now maybe that the guys who designed these systems took this into account and built the valves with a mechanical interlock so this couldn't happen. But it's just as likely that put the interlock in software because computers are more reliable than mechanical devices and cheaper as well.
We even have the villain telling us that he is 'doing America a favor' by hacking all the computer systems that control our infrastructure, but did the yahoos at Colonial listen? No, they did not. Flipping morons. We're lucky Darkside decided to just shut down the pipeline and not blow up ever pumping stations and tank farm along the way.
In any case we had this warning about how industrial computer systems are susceptible to being hacked fourteen years ago and the yahoos in charge didn't listen. Typical.
P.S. I believe the pipeline in the movie was a natural gas pipeline, not gasoline, but the situation is similar, if not worse. Natural gas may not be as dense as gasoline, even when compressed to a zillion PSI, but with that much pressure everything is going to much more stressed and just as susceptible to blowing up due to improper operation as a regular liquid pipeline.
1 comment:
They did not (could not?) take control of the pipeline, they took control of the billing system so Colonial shut down because they couldn't get paid. That same pipeline also carries diesel, plus jet fuel to the major airports in NY, DC, and Atlanta. There are dozens of branches off the main trunkline.
Dad taught me the rule of thumb, double the diameter quadruples the capacity.
I don't believe the pipeline explosion in the movie can happen. There could be (has been) an explosion at some point but it wouldn't follow the pipe like a burning fuse. The fire can get more intense but no more explosions like a series of tanks would.
Enjoy your holiday.
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