ISO 630 grade E275 quality C plates API 650 cylindrical welded storage tanks

Design of Compression-ring Regions
In this project, a cylindrical tank 30 ft in diameter is designed for an internal pressure of 5 lbf/in.2 gauge in the vapor space. The plate material is ASTM A131 Grade A steel for thicknesses of 1/2 in. and less. The top course of the butt- welded cylindrical sidewall is 1/4 in. thick, including a 1/16 in. corrosion allowance. The tank API 650 cylindrical welded storage tanks roof is a butt-welded spherical dome with an internal radius of 30 ft and a thickness of 1/4 in., including a 1/16 in. corrosion allowance. The maximum design liquid level is 6 in. below the plane of the juncture of the roof and sidewall.

While GB50341 generally takes the weld coefficient as 0.9;When the minimum yield strength of API 650 cylindrical welded storage 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.

Prefabrication requirements for API 650 cylindrical welded storage tanks, large vertical storage tanks:
1. The machined surface of the edge of the steel plate should be smooth, and there should be no defects such as slag inclusion, delamination, cracks, etc., and the surface hardened layer produced by the flame cutting groove should be removed.
2. Dimension deviation after steel plate processing: the deviation of plate width is less than 1.5 mm, the deviation of plate length is less than 2 mm, and the difference between diagonals is less than 3 mm.