PSI versus weight

[rasorinc]

I need some help from someone more knowledgable in math than I.

If you have a 20" inside diameter pipe that is approx. 315 square inches. and it is discharging water at 5,000 pounds per square inch, how heavy a weight would you have to have to place over the top of the pipe to stop the flow? In pounds please. Thanks much, I really appreciate the assistance. Stan

[marshmat]

The pipe's pointing straight up? And you just want to put something on top of it that's heavy enough to stop the flow and not get pushed off?

Very roughly, then: a water jet of 315 sq.in at 5000 psi is enough to lift (315*5000)=1575000 lb or about 703 tons (in air). The actual cap would of course have to be heavier, if you do want it to stay put. Obviously, if this is a situation you're actually faced with, you'll need a few engineers.

This wouldn't have anything to do with trying to understand the Deepwater Horizon oil spill, would it?

[SheetWise]

Originally Posted by marshmat

This wouldn't have anything to do with trying to understand the Deepwater Horizon oil spill, would it?

I think he's talking about a through-hull fitting on the bottom of the Queen Mary 2. OTOH -- you may be right.

[murdomack]

Originally Posted by marshmat

The pipe's pointing straight up? And you just want to put something on top of it that's heavy enough to stop the flow and not get pushed off?

Very roughly, then: a water jet of 315 sq.in at 5000 psi is enough to lift (315*5000)=1575000 lb or about 703 tons (in air). The actual cap would of course have to be heavier, if you do want it to stay put. Obviously, if this is a situation you're actually faced with, you'll need a few engineers.

This wouldn't have anything to do with trying to understand the Deepwater Horizon oil spill, would it?

You are thinking of cutting the casing and driving a weight bung in to stop the leak aren't you, being a piping man I have had this thought as well.

The problem is that if the well pressure is 5000psi, although the weight would throttle it somewhat, the pressure would then build up and probably blow the casing apart. From what I have read in the news this leak is probably coming up the annullus within the casing and also up the annullus between the casing and the rock. It's totally out of control by the sound of it.

If the relief wells don't kill it, they will have to look at burying it with weight, as you say, or nuke it and hope it closes itself in.

[rasorinc]

Thanks everyone. That is a lot of lead though when calculating the weight of sea water pressure at a mile down not as much as I guessed at. I appreciate the assistance. Stan