API Std 650 duplex stainless steel tanks primary drains

The API Std 650 duplex stainless steel tanks 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 internal floating roof oil tank executive standard: domestic design standard: GB50341-2003 "Vertical cylindrical steel welded oil tank design code"; domestic construction standard: GB50128-2005 "vertical cylindrical steel welded oil tank" Construction and Acceptance Specification; API Std 650 duplex stainless steel tanks Foreign design standard: API650-2007 "Standard for Welded Steel Petroleum storage tanks."

Usually, the soil resistance of the foundation should be considered before the design and construction of API Std 650 duplex stainless steel tanks. The soil endurance in the API Std 650 duplex stainless steel tanks construction area plays a decisive role in the basic cost of the tank. In areas with high soil resistance, not only the cost of foundation treatment can be greatly reduced, but also the ratio of height to diameter of storage tank can be obtained. Therefore, the investment cost of the API Std 650 duplex stainless steel tanks can be greatly saved in the area with large soil resistance.