Maintenance site feedback indicates leakage between the plates of the BR-95 plate-and-frame heat exchanger, with the fastening bolts not loosened. Such issues often point to deviation in the clamping dimension, improper gasket matching, or a pass arrangement inconsistent with the operating conditions, and should be investigated in sequence.
Compared with shell-and-tube heat exchangers, the plate-and-frame structure is compact and has a higher heat transfer coefficient, but it is more sensitive to the matching of gaskets and plates. Gasket material must balance temperature resistance and chemical resistance; the common types are nitrile, EPDM, and fluororubber, which should be matched according to the medium type and operating temperature, and confirmed together with the plate material. Nitrile is suitable for oil media, EPDM resists water and steam, and fluororubber is suitable for high-temperature or corrosive-component conditions; selection should be based on the medium compatibility table.
When leakage between plates is found, first confirm whether the clamping dimension is within the range marked on the nameplate. Too small a clamping dimension over-compresses the gasket, while too large a dimension results in insufficient sealing specific pressure; both may cause leakage. If the clamping dimension is normal, then check whether the gasket is aged and whether there is foreign matter or deformation in the plate sealing groove. Compared with shell-and-tube heat exchangers, which rely on welding the tube bundle to the shell for sealing, the detachable structure of plate-and-frame heat exchangers facilitates cleaning, but the number of sealing points is large, and each plate must be verified during maintenance.
The determination of the pass arrangement should take the actual flow rate, inlet and outlet temperatures, and allowable pressure drop as inputs, and determine the number of plates and number of passes through heat transfer calculation. Compared with shell-and-tube solutions, plate-and-frame heat exchangers can adjust the heat transfer area by adding or removing plates, offering high flexibility, but an increased number of passes leads to higher pressure drop, which must be weighed during the selection stage. When verifying, technical engineers should take the clamping dimension, gasket material, and pass arrangement as three basic inspection items to avoid misjudgment based on a single factor.
