If the pressure exceeds design limits, the plug pops out to depressurize the pot.
If the pressure exceeds the limit of the safety valve, water in the form of gas is lost.
Therefore, pressure at the shoe of the 'B' annulus cannot exceed this.
When the pressure exceeds this value the valve opens and sends the flow to return line.
The pressure would exceed a hundred standard atmospheres.
Although external pressure cannot exceed one atmosphere, that can suffice to collapse the vessel in some cases.
This is because the pressure inside the bubble exceeds (by far) the vapor pressure of ocean water.
The pressure in the wellbore must also exceed the rock matrix strength.
Slowly the pressure built up until finally the internal pressure exceeded the limits of the molten steel.
This pressure may exceed the strength of the paper case, causing the motor to burst.
