Some common mistakes made in pressure vessel design

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Here are some common mistakes made in pressure vessel design, summarized for your reference. 01 The general layout shall indicate the operating pressure, temperature, toxicity level of the medium, and explosion hazard level. For those that cannot undergo internal inspection due to structural reasons, the requirements for regular inspections during use should be specified. 02 The standard for carbon steel Q235 series steel plates should be GB/T 3274; it is mistakenly taken as GB 700. GB 700 is a standard for the grades and chemical composition of carbon structural steel, not a standard for carbon structural steel plates. 03 The seamless steel tubes selected only indicate the steel grade, without specifying the standard for those tubes. Seamless steel pipes of the same grade but different standards exhibit significant differences in quality and applications. 04 The grade of the selected forging is not specified. 05 Inadequate consideration was given to the compatibility of media and materials; for example, stainless steel was used in environments prone to intergranular corrosion and stress corrosion. 06 The selection of stainless steel took corrosion allowance into consideration inadequately, increasing the cost of the equipment. 07 When the medium environment is subject to corrosion such as intergranular corrosion, stress corrosion, pitting corrosion, and crevice corrosion, the corresponding corrosion resistance testing methods and necessary heat treatment requirements are not specified in the design drawings. 08 There are no requirements regarding the pickling and passivation of stainless steel or non-ferrous metals. 09 The bolt assembly does not specify the material number or quality grade requirements. 10 The lack of welding joint diagrams, especially those specifying the welding requirements for nozzles and shells, can result in incomplete weld penetration in structures that require full weld penetration. This leads to crevice corrosion, which may cause fluid leakage or serve as a source of cracks. 11 The welding method and welding material have not been specified. Both the welding method and welding materials shall be determined by the manufacturing unit. 12 For applications subject to stress corrosion, the specified limit for the concentration of the corrosive medium is not indicated. 13 The saturated vapor pressure and temperature do not correspond. 14 The external natural conditions in the location where the pressure vessel is used (such as ambient temperature, seismic design intensity, wind and snow loads, etc.) are not taken into account; it is possible that the operating environment conditions may exceed the ranges specified in the design requirements.