API standard 650 welded storage tanks hydrostatic testing requirements

Service Conditions and Hydrogen-induced Cracking
When the service conditions might include the presence of hydrogen sulfide or other conditions that may promote hydrogen-induced cracking effects, particularly near the bottom of the API standard 650 welded storage tanks shell at the shell-to-bottom connections, care shall be taken to ensure that the materials and details of construction of the tank are adequate to resist hydrogen- induced cracking. The Purchaser shall consider restricting the sulphur content of the material to be stored through thickness testing of the steel, laboratory surveillance tests, and the use of internal tank coatings to reduce the possibility of hydrogen-induced cracking.

The application of API 650 is as stated by the American Petroleum Institute: The production and installation of our ground welded steel API standard 650 welded storage tanks storage tanks are generally used in industry; under normal circumstances, the storage tanks installed on the industrial site in the United States are in accordance with API 650, API 620 and API 12d Standards are established.

Static storage loss is also known as "small breathing" consumption. The rise and fall of the temperature in the API standard 650 welded storage tanks leads to the increase and decrease of the pressure in the tank, which makes the mixed oil gas discharged from the tank, and the external air is sucked into the tank, resulting in the oil consumption. Fluid level loss is also called "big breathing" loss. It is the oil consumption caused by the change of gas space volume in the API standard 650 welded storage tanks during the oil receiving and sending operation, which causes the mixed oil gas to be discharged out of the tank, and the external air is sucked into the tank, resulting in the oil consumption due to the change of liquid level height.