Regarding the issue of container sheet rolling forming
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For large-diameter vessels (such as those with a diameter of φ8000 or more), what is the appropriate manufacturing process for joining them together: to form them as single pieces first and then weld them together, or to weld them together first and then roll them into the desired shape? I would appreciate it if experts could share their views on its advantages and disadvantages!
The master said that the single pieces are formed first and then assembled. As for why this is done and what the differences between the two methods are, I still don’t know. I need to ask next time to find out.
It would be better to perform single-piece molding followed by assembly welding; if the latter method is used, there are uncertainties such as stress concentration near the weld seam
I’ve never worked on containers of that large diameter before
With such a large diameter, it is not easy to form it by directly rolling the sheets together; the factory facilities and lifting equipment pose challenges in this regard. It would be better if the rolling machine were vertical. Additionally, the transportation of the finished product needs to be taken into consideration, so it’s preferable to manufacture it in sections. Attention should be paid to the pre-bending of both ends of the curved sections; they should be stored upright during transportation to prevent deformation. During on-site assembly, it’s important to control the roundness of the sections, the parallelism of their end faces, as well as the outer circumference of each section, so that no problems will arise during assembly.
In manufacturing plants, components are usually first formed as individual pieces before being assembled together, especially for equipment with larger diameters. This is because large-diameter sheets are difficult to maintain in their proper geometric shape, and measures such as internal support are required; each section must achieve the allowable geometric tolerance before it can be assembled with the others.
A container of such a large diameter is normally a large vertical storage tank. The tank shell is assembled on-site, with the sections being formed first and then joined together, which improves production efficiency.
I asked the technician this afternoon, and he said that large-diameter plate rolling machines do not have the capability to achieve this. Especially for the large storage tanks used in oil fields, which usually have a diameter of over ten meters and are quite tall, large-diameter tanks are generally assembled on-site: first, each section is formed separately, and then they are joined together, with adjustments being made continuously during the assembly process. This post was last edited by greenbud on 2009-3-3 15:55.]
The length of the wall panels should not exceed eight meters; they are formed from single sheets of metal (preferably with flanges), and are assembled using an inverted fitting method. After being combined into one unit, the circumferential seams are welded first, followed by the longitudinal seams. Saves labor, effort, and cost; high efficiency and low cost.
The length of the wall panel depends on the thickness of the steel plate used; a greater thickness allows for a longer length.
A device of this size must be installed on-site. After single-piece molding, it is transported to the site for assembly and welding. If it is shaped after assembly, it simply cannot be transported.
It’s extremely difficult to roll them up after assembly. Generally, tanks of this size are manufactured on-site, with each section being formed separately before assembly, which also makes lifting them easier. Anyway, that’s how our factory has always done it