API Std 650 unanchored flat-bottom tank liquid-mounted seals

The API Std 650 unanchored flat-bottom tank stiffener ring and backing strip (if used) are primary components, and they shall comply with the requirements of API 620 storage steel tank Q.2.1. The stiffener rings may be fabricated from plate using an intermittent weld on alternating sides between the web and the flange.
Except for aluminum or stainless steel tanks, all fillet welds shall consist of a minimum of two passes. The ends of the fillet welds shall be 2 in. from the rat hole (see Figure Q-1), and these welds shall be deposited by starting 2 in. from the rat hole and welding away from the rat hole. An acceptable alternative to the detail that includes stopping fillet welds 2 in. short of the rat hole would be to weld continuously through the rat hole from one side of the stiffener to the opposite side. All craters in fillet welds shall be repaired by back welding.

API 650 storage tank is used for commonly used oil, gasoline, diesel, chemical and production water storage. API Std 650 unanchored flat-bottom tank Storage tanks built to these standards are spread across U.S. refineries, terminals, pipelines, and production facilities. The API 650 detailed standard specifies the design, processing, welding, inspection and installation procedures for storage tanks.

Due to the volatility of oil products, the volatile consumption of oil products is inevitable in the storage process of large oil storage tanks such as API Std 650 unanchored flat-bottom tank. The volatilization of oil causes economic losses and pollution to the environment. Especially in the open air environment, large-scale oil storage tanks in the petrochemical industry will continue to accumulate energy when exposed to the sun, causing their surface and interior to heat up rapidly, causing sun overheating, and accelerating the volatilization of oil. How to effectively reduce the volatile consumption of large oil storage tanks?