API 650 flexible liquid storage tanks examiner

The factors affecting the "small breathing" loss of API 650 flexible liquid storage tanks are: 1. It is related to the change of temperature difference between day and night. The greater the change of temperature difference between day and night, the greater the loss of "small breathing"; on the contrary, the smaller the change of temperature difference between day and night, the smaller the loss. 2. It is related to the sunshine time of the oil storage tank. The longer the sunshine, the more the "small breathing" loss; otherwise, the less the loss.

In this project a cylindrical tank 75 ft in diameter is designed for an internal pressure of 0.5 lbf/in.2 gauge in the vapor space. The plate material is ASTM A131 Grade B steel for thicknesses of 1/2 in. and less.
The top course of the butt-welded cylindrical sidewall is 1/4 in. thick. The tank API 650 flexible liquid storage tanks roof is a conical shape with a 2:12 slope and a 1/4 in. thickness with single full-fillet welded lap joints. The maximum design liquid level is 6 in. below the plane of juncture of the roof and sidewall.

The inner layer of API 650 tank is the same as that of single layer tank. It is made of high-quality steel plate in strict accordance with the standard of "steel welded atmospheric pressure vessel". The thickness of API 650 flexible liquid storage tanks steel plate reaches the standard and the service life is longer.