API 650 flat-bottom tanks appurtenances and attachments

Prefabrication requirements of API 650 flat-bottom tanks, large vertical storage tank wall panels:
1. The prefabrication of wall panel shall be processed in strict accordance with the requirements of the drawings, and inspection records shall be made.
2. After the wall panel is rolled, it should be placed on the platform for inspection with a template. In the vertical direction, use a straight-line template to check, the gap should not be greater than 2 mm, and in the horizontal direction, use an arc-shaped template to check, and the interval should not be greater than 4 mm.
3. When wall panels are rounded, attention should be paid to prevent irreversible plastic deformation caused by external forces. After rolling, it should be placed on the platform for inspection, and then placed on the prepared mold.

Ultrasonic Examination of Butt-welds in Plates
Butt-welds in all tank wall courses subjected to a maximum actual operating membrane tensile stress, perpendicular to the welded joint, greater than 0.1 times the specified minimum tensile strength of the API 650 flat-bottom tanks plate material shall be completely examined.
Butt-welds in API 620 oil tank wall courses subjected to maximum actual operating membrane tensile stress, perpendicular to the welded joint, less than or equal to 0.1 times the specified minimum tensile strength of plate material shall be spot examined in accordance with Figure Q-2.

While GB50341 generally takes the weld coefficient as 0.9;When the minimum yield strength of API 650 flat-bottom tanks steel plate is greater than 390 MPa, take 0.85. The thickness of API 650 tanks is generally smaller than that of GB50341, and this difference is particularly evident in the design of large tanks, where the overall weight of the tanks varies greatly.