Allowable load of pipe flanges
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The equipment jacking blocks are made up of pipes, and it is necessary to verify the stress on the interface flanges, as well as to determine whether the flanges on the pipes have an allowable load limit; there are also relevant standards that can be referred to
The stress at the flange should be checked by a specialist in equipment design or by the manufacturer.
The maximum allowable operating pressure for flanges is determined by the temperature; the operating pressure must not exceed this value, and this is specified in flange standards such as HG 20592. Generally, no strict calculations are required for flanges, as over the years their standards have undergone extensive practical testing; as long as the appropriate flanges are selected, reliability can be ensured. This situation is rare unless an exceptionally large external load is applied to the flange; there are specialized books on flange calculations, which are rather niche in nature. What was mentioned upstairs refers to the pipe ends; strictly speaking, the flange has little impact on this – what’s important are the welds along the pipe segment between the flange and the equipment. Regarding pipe ends, efforts should be made to minimize stress when arranging the pipes. The book \"Stress Analysis of Pressure Pipes\" by Tang Yongjin introduces a vague criterion: the stress at small-diameter pipe ends should not exceed 70 MPa; however, there is no clear definition of what constitutes a small diameter. The book also provides a calculation formula for this, but it is rather vague as well. Generally, manual calculations are not performed; nowadays, the stress on the pipe ends is calculated using CII software, and then the mechanical engineering team uses finite element software to conduct further analysis. For those cases where the stress is too high, reinforcement measures must be specified in the equipment design drawings. As mentioned above, it is sent to the equipment manufacturer for verification, and the equipment manufacturer uses the same method. Large design institutes* prefer to do the calculations themselves, as it’s better to have armed forces at hand. Smaller design firms have weak military capabilities; they can’t afford the necessary software, so they end up giving it up, and disputes in the future are hard to avoid.
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Practical practice: In the stress summary, if the stress on the flange nodes does not exceed 60%, it is assumed that the flange will not leak, and there is no need to use a dedicated flange module for further verification