Squeeze / pinch the oil-pipe closed (why didn't they listen to me?)

Why BP didn't pinch the pipe with hydraulic device to close or slow the spill? (sufficient clamping force would close any steel tube tight). I had this idea for some time now. After I googled it I saw there are also other people with this idea.

• Issues with this idea
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Static oil/gas pressure difference could be the reason why. If it is higher than pipe wall can handle (one inch thick, right?) then there is no way to 100% stop the flaw AFTER blowout preventer. Pipe rupture shouldnt be the issue before BOP. I don't know exact pressure figures. My calculation shows that static oil/gas pressure difference is not problem if it is smaller or equal 4*S*W/D, whe S=steel strength, W=tube wall thickness, D=inner diameter of tube. But it could be irrelevant if flaw is supposed to be stopped during normal use at some valve after blowout preventer since it this case tube is sufficiently dimensioned to withstand static pressure difference.

Although static oil/gas pressure difference could really be enormous, dynamic pressure must be many times smaller. Why? Because viscous resistance rises with square of speed. And flow needs speed. After few miles of viscous traveling inside pipe, dynamic pressure will drop significantly. Here lies beauty of this solution: clamped section of pipe will act as resistance valve. In other words, if speed gets too slow, pressure will rise and open the pinch as much as needed. It will reduce flaw significantly and remaining spill they can pick with "top hat" or whatever.

Another problem could be behavior of steel at corners of pinched pipe (cracks because of exceeding of steel elongation capacity). This one is easy tested on actual tube if one has sufficient clamping force. If not, it can be tested at smaller scale model (diameter/tube wall ratio should be the same). This is what I will try to do. Even if pipe cracks at the ends, there are measures that can prevent or reduce this cracking. It should be interesting...

• Seeing is believing
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I did pinching test on smaller scale tube. Absolute dimensions don't matter for principle testing as long as relative proportions are kept. Tube outer diameter was 60.3 mm (2.374 in) with wall thickness 4.8mm (0.189 in) making ratio of outer diameter (o.d.) to tube wall equals 12.56. As far as I know raiser pipe has o.d. 21 inch and wall 1 inch with ratio 21.00. Therefore my test tube was "thicker" and more prone to cracking when pinched flat than the actual raiser pipe (this is true as long as material of both pipes have same elongation capacity). Material of test pipe was low carbon steel (S235 or equivalent) with theoretical elongation at break somewhat higher than 20%).

I used my company 100t press. I flat pressed two pipe specimens: one small slice and one longer segment. And it was clear success! Pipe was closed shut with no material cracks.

Pipe was closed tight with relatively small force (around 50t). As long as force is applied it remained completely shut. I made photos and video. Below is just few photos. More photos and video on link here. Also I will upload video of pinched tube on youtube. Here is forum to discuss. Stay tuned...

• How much clamping force is needed for the real thing?
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Initial fazes of pipe pinching go without much resistance. The last part when pipe is crushed shut requires serious force. Based on scale ratio from my experiment I think sufficient force for 21 inch pipe will be 435 t. This should be no problem.

pictures and video:
http://www.kontakt-ing.com/oil_spill_pipe_pinch.html

D

Heard today BP finally stop the flow of oil




They placed a large wedding ring over the pipe and the well stop producing.

Can anyone say "O Rings"...Like space shuttle disaster O
RINGS.Management is always management.BAD