Regarding the selection of pipe wall thickness
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In the process of calculating the pipe wall thickness according to SH/T 3059, it was found that even when the corrosion allowance, manufacturing negative deviation, machining depth, and rounding values were all taken into account as specified, the resulting nominal wall thickness was still much thinner than that of commonly used, standard pipe walls. For example, the wall thickness calculated for a DN500 pipe might be only 4 mm, whereas the typical wall thickness used in practice is 7 mm or even thicker; this phenomenon was observed across several grade tables. What is not clear at present is whether, in the process of selecting the wall thickness, there are any other substantive or empirical factors that cause the actual wall thickness to be greater than the calculated value, and how these factors are taken into account.
Some material pipes have minimum thickness requirements. The minimum required wall thickness as calculated. https://bbs.hcbbs.com/thread-2981135-1-1.html
Your calculated thickness is 4mm, with a corrosion margin of 2-3mm – isn’t that roughly 7mm? One also needs to consider the thickness commonly used in one’s own company.
In addition to considering the wall thickness strength of the pipe under internal pressure, the stiffness of the steel pipe itself must also be taken into account. Some standards require a minimum wall thickness for pipes.
Additional factor: 1. The specifications require a minimum wall thickness； 2. The span requirements for pipes are such that, for thin-walled pipes, the distance between the points at which their cross-sections intersect is much smaller. As a result, the span of the pipe supports required during pipeline installation is also reduced, which increases the number of pipe supports and thus raises the civil engineering costs, making it uneconomical ； 3. Pipes with certain common wall thicknesses are easier to purchase.