"BP engineers planned to shut off pipes that are already funneling
some oil to two ships, to see how the cap handles the pressure of the
crude coming up from the ground. Then they planned to close, one by
one, three valves that let oil pass through the cap."

Got to catch a few more dollars worth of oil, before turning off the
spigot, eh?

They have to stop the flow gradually .. if they slam it shut, it will
cause the world's largest case of "water hammer" and it could be enough
to blow a hole someplace in the earth's crust that could NEVER be repaired.