Minimum thickness of shell-side cylinder

Comply with GB/T151 regulations, mainly considering stiffness.

1. The determination of the minimum thickness of the heat exchanger shell is primarily aimed at ensuring sufficient rigidity of the shell, thereby reducing deformation and facilitating the installation of the tube sheet and tube bundle. Especially for the shells of floating-head and U-tube heat exchangers, since there is no tube sheet to provide support and these shells need to be disassembled, it is even more necessary to ensure a certain thickness. 2. For horizontal heat exchangers that are used in a stacked configuration, their saddles and nozzles exert significant local stresses on the shell-side cylinder. To this end, it may be appropriate to increase the minimum thickness of the shell; 3. Increasing the minimum thickness of the shell-side cylinder also helps to conduct leakage tests on the pipe joints in the shell side of heat exchangers that have high design pressures on the tube side; 4. If design is carried out in accordance with GB151, its regulations regarding minimum thicknesses must be followed. If the corrosion allowance in the design is increased, it should be adjusted accordingly. GB151 specifies a corrosion allowance of 1 mm for low-alloy steel; if the corrosion allowance is 2 mm, an additional 1 mm should be added to the minimum thickness.

The purpose of specifying a minimum thickness for the shell is, first, to increase the stiffness of the shell and reduce deformation; this facilitates both the installation of the tube sheet and the tube bundle, and stiffness is particularly important for U-tube and floating-head heat exchangers, where the tube bundle needs to be frequently removed and reinstalled. 2. Sometimes, heat exchangers need to be installed overlapping each other; to reduce the local stress on the shell caused by the supports, it is necessary to control the minimum thickness.

Maintaining the necessary rigidity is conceivable. But this question has also troubled me for a long time: how can one determine whether the rigidity is sufficient? Please, experts, explain the specific steps. Thank you

How is this minimum thickness determined? What are the problems in practical applications if this minimum thickness is not followed? There is a reason, but it doesn’t seem specific.

GB150 follows a standardized design approach: some aspects are based on formulas while others rely on experience; simply follow the guidelines. If you have different ideas, use JB4732 for analysis and design

The minimum thickness is derived from experience and practice, 5

It is mainly about stiffness; there may be supports to prevent deformation from affecting the installation of the piping system. However, based on actual usage, it is clearly unreasonable for very small heat exchangers.

This post was last edited by wanlirn on 2020-1-7 at 08:51. It’s obvious – the stress formula takes into account only the internal pressure requirements on the shell. Heat exchangers have tube sheets, and some of these tube sheets also serve as flanges. In addition, there are thermal stress effects; for horizontal heat exchangers, there are also saddles, while vertical ones rely on supports. When designing heat exchangers, has anyone ever required you to use the formulas for horizontal containers for verification? For vertical heat exchangers, if their height is large, there are also wind loads, seismic loads, and so on. The standards do not provide quantitative calculation formulas for these. In our design system based on GB150 regulations (which is primarily based on experience), predecessors have established minimum thickness requirements for shells along with other guidelines based on their experience； How can you be so simple-minded as to consider the suction tube as the main cause?