Reason Analysis on Top Sag of Oil Tank

Taking the top sag of oil tank as an example, the author considers the overrated negative pressure to be the major reason of tank top sag. Some elements that plugging of fire-arrester, unmatchable rated breathing vs oil loading/unloading and so on result in the sag of tank top. It is suggested that the corrugated-type fire-arrester should not be selected for the heavy crude oil tank.