This article mainly stipulates the requirements for the liquid level of internal floating roof storage tanks. The bottom of the floating plate means that the floating plate falls on the support leg due to the low liquid level of the storage tank. During normal operation, when the floating plate falls to the bottom, a gas phase space will be formed between the floating plate and the oil surface. When the material flow rate is too fast, static electricity at the pipe orifice of the material pipeline is likely to accumulate, which can easily cause fire and explosion accidents.

A typical accident case: 

On August 29, 2011, a diesel tank of PetroChina Dalian Petrochemical exploded and caught fire. The main cause of the accident was the low level of oil from the storage tank. A gas phase space was formed between the floating plate and the diesel liquid level, causing air At the same time, the operation of the upstream device fluctuates, and the content of light components in the diesel oil entering the accident storage tank increases, forming an explosive mixture below the floating plate; In addition, the flow rate of the oil is too fast, a large amount of static electricity is generated and cannot be discharged in time, resulting in discharge, causing an explosion and fire .