Oceans of Opportunity

delta P | dealing with pressure, under pressure


'A New Life in the Sea' by Michael LombardiThis past week marked the continuation of a field project that I have been involved with since early in the fall involving dam repair work. Aside from tight tunnel penetrations, in my opinion, I’d say dams are among the most hazardous of working dive environments. This is to to one thing – pressure.

In commercial diving we refer to pressure related environmental hazards as ‘delta P’, or ‘change in pressure’ or ‘differential pressure’. Quite simply, the diver is working in or near an environment at an ambient pressure that is different from a nearby ambient pressure. Often times all that is holding this pressure back is a pipe, wall, gate, or some other manmade structure that is quite likely compromised – hence the need for a diver to make a repair. I guess that’s why we get paid the big bucks.

Oil Platform Disasters: Collapsed Oil Platforms, Piper Alpha, Ocean Ranger, Lake Peigneur, Alexander Kielland WreckAs contract divers, we work at depth, or ‘under pressure’ all day. We see the effects of pressure on the environment, on structures, on our equipment, and on ourselves day in and day out. For those who do not, it can be difficult to conceptualize just how powerful water is. Factor in job-related stress and a different type of ‘pressure’, and communications can become tense to say the least.

We avoided any safety issues this week, but it was not without some much expected stress. I short, we had a void to shore up behind a cofferdam that was somewhere around 1400 square inches in area. The problem was that at 20 feet of depth with the cofferdam near dry behind it, this void has about 10 pounds per square inch of pressure on it, making for 14,000 pounds of force to overcome for a proper repair. No simple task, but I am here to write about it so suffice to say we were successful.

Pressure cannot be taken lightly. This week’s workload reminded me of an OSHA safety video that I watched at one point (yes, safety training is there for a good reason) about the Jefferson Island disaster back in 1980. This video shows the effects of pressure differential better than any other:

In short, an oil drilling company was drilling a test hole through the bottom of Lake Peigneur in Lousiana. They were in the wrong location, and tapped into a salt mine that ran beneath the lake. Scary does not begin to describe the events that then took place. Not only did the entire lake get sucked into the mine, but a good chunk of Jefferson Island was sucked in, as well as an entire flotilla of barges and other vessels on the lake. Louisiana experienced a sneak peak at Armageddon that day.

Lesson for the day is to not underestimate the power of mother nature. It, and physics, has been here much, much longer that we humans have. While we understand some of it better than other parts, for those who work in, under, or around the water – follow this short bit of advice: “a little bit of physics, and a whole lot of common sense goes a long way”.

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  1. Pingback : a bit more pressure | Oceans of Opportunity

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