API standard 650 SUG I tanks details of welding

Under the condition of static storage without receiving and sending operation, the temperature of gas space, evaporation rate, depth and pressure of vapor in the API standard 650 SUG I tanks will change with the change of temperature and pressure in a day. The oil loss caused by the process of discharging oil vapor and inhaling air gas is called "small breathing" loss, which is also called static storage loss of oil tanks.

A refrigerated tank may be a single-wall insulated tank or a double-wall tank that consists of an inner tank for storing the refrigerated liquid and an outer tank that encloses an insulation space (which usually has a lower gas pressure) around the inner tank. A double-wall tank is a composite tank, and the outer tank is not required to contain the product of the inner tank. In a double-wall tank, differences in API Standard 620 tank materials, design, and testing exist between the inner and outer tanks.

This standard only applies to API 650 storage tanks API standard 650 SUG I tanks with uniform bottom support and non-refrigerated service storage tanks with a maximum design temperature of not more than 93 degrees Celsius (200 degrees Fahrenheit).