May I ask: What is a double-disc floating roof tank?

From the information I found on my own: Single-disc floating roof: It is a compartment with an annular cavity formed at the edge of the floating deck; it is also known as a \"cabin.\" Double-disc floating roof: The floating deck is covered by two layers of steel plates, and the space between these two layers is divided into several airtight compartments using radial and circumferential partitions. This forum: http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=757280 Floating roofs come in various forms, including single-disc floating roofs, double-disc floating roofs, and float-type floating roofs. Single-disc floating roof: It consists of several separate compartments forming a ring-shaped float, with a single-disc roof on the inner side of this ring. The bottom of the single-disc roof is reinforced with multiple annular steel rings. Its advantages are low cost and easy maintenance. Double-disc floating roof: It consists of an upper disc plate, a lower disc plate, and deck edge plates, and is divided into several separate annular compartments by radial and circumferential partitions. Its advantages are high buoyancy and excellent drainage performance. " They are mostly of steel structure; there are also fiberglass versions in single-disc form.

A single disk structure consists of a circular steel plate in the middle, with circular cabins surrounding it; whereas a double disk structure means that the entire floating vessel is made up of cabins

In my opinion, the heights of the dual-disc and single-disc versions seem to differ by a few hundred millimeters; the way they function during use is the same though