If temperature differences and material matching are overlooked during the design and selection stage, tube sheet cracking or tube bundle pitting may occur after commissioning. For the GCH-300 shell and tube heat exchanger operating under conditions where the temperature difference exceeds 60°C, the fixed tube sheet structure can be equipped with an expansion joint to relieve thermal stress; the wall thickness of the shell and tube bundle is determined by classification according to the design pressure, and the design temperature is used to verify the material expansion allowance. During selection, the tube-side and shell-side media must be checked separately to identify corrosive components, avoiding local thinning caused by incorrect material matching.
When the design temperature difference between the tube side and shell side exceeds 60°C, the fixed tube sheet structure should be provided with an expansion joint. Selection personnel should calculate the temperature difference based on the hot-end and cold-end temperatures provided in the process package, and determine the expansion joint type and compensation amount in conjunction with the design pressure. If the temperature difference approaches the critical value, the option of switching to a floating head or U-tube structure may be evaluated to reduce shell thermal stress.
It is recommended to record the secondary-side outlet temperature once a week. When the reading deviates from the design value by ±5°C, the flow distribution, fouling degree, and bypass valve status should be investigated rather than directly adjusting the heat source parameters. The recorded data are also used to determine the trend of tube bundle heat transfer efficiency changes and to provide a basis for the cleaning cycle.
Operation and maintenance personnel can verify the tube bundle and shell materials separately according to the tube-side and shell-side media, focusing on chloride ion content and flow velocity distribution. For areas prone to deposition, the pitting risk should be assessed in conjunction with shutdown inspections, and if necessary, the medium flow velocity should be adjusted or anti-corrosion coatings should be added.
