Will large storage tanks collapse after being drained after a hydrostatic test?
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For large containers, after testing the water pressure and waterproofing, if the liquid is drained directly without opening the vent valve, everyone may have this engineering experience. When the liquid is drained to a certain extent, the water in the tank can no longer be drained out. At this time, the pressure in the tank + the liquid column in the tank = atmospheric pressure. In other words, if the liquid column in the tank is very high, such as greater than 10m, then the liquid in the tank will flow until the pressure in the tank is close to the saturated vapor pressure of water. This kind of vacuum is usually unbearable by ordinary large storage tanks. On the other hand, chunky containers are relatively safer. Please discuss whether this is the case.
If it is an external floating roof tank, there will be no problem. If it is a vaulted roof tank or an internal floating roof tank, if you do not open the vent hole on the top of the tank, the tank will shrink into a ball.
Pay attention to the drainage speed when draining, and there are also requirements for the diameter of the vent pipe on the top of the tank. Otherwise, instability and deformation may easily occur during drainage.