API 650 ambient temperature tanks structural period of vibration

The API 650 ambient temperature 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 sets minimum requirements for the design, material, construction, and testing for aboveground, open and closed-top, cylindrical API 650 ambient temperature tanks steel storage tanks in different capacities and sizes, roughly equating to the pressure of the atmosphere (not greater than the weight of the roof plates).

Prefabricating API 650 ambient temperature tanks components before construction can improve construction efficiency, save time and cost, and is currently a common method for the construction of large vertical storage tanks. The main prefabricated components of a large vertical API 650 ambient temperature tanks include the tank body, the storage tank wall, the top of the storage tank, the bottom of the storage tank, and the accessories of the storage tank. The prefabrication of the components should follow a reasonable workflow, and carry out appropriate heat treatment and testing, so as to improve manufacturing accuracy.