During on-site inspections, leakage traces are often found at the gasket of heat exchangers, and after disassembly and inspection, this is mostly related to a mismatch between the gasket material and the actual medium temperature. For design and selection personnel, mastering the key points of material matching and parameter confirmation for plate-and-shell heat exchangers in typical application scenarios helps reduce such problems.
In secondary-side central heating or domestic hot water preparation conditions, when the medium is hot water below 120°C, EPDM gaskets can be selected, and 304 or 316L stainless steel plates can meet general water quality requirements. During selection, the design pressure, inlet and outlet temperatures, and flow rate should be provided to the supplier to facilitate calculation of the heat transfer area and plate combination method, avoiding direct ordering based on estimated area.
When used for cooling lubricating oil, hydraulic oil, or recovering low-temperature waste heat, if the medium temperature does not exceed 80°C and is oil-based, NBR gaskets have good adaptability. The plate material must be determined based on the corrosiveness of the medium; for media containing chloride ions or weakly corrosive media, 316L stainless steel is recommended, and titanium may be selected when necessary. The fouling factor and allowable pressure drop should be specified in the parameter table to allow reasonable arrangement of the flow path.
When in contact with acidic or corrosive media at temperatures below 180°C, fluorine rubber gaskets are a common choice. Selection personnel must focus on confirming the chemical composition, concentration, and operating temperature of the medium, and match the plate and gasket materials accordingly. For highly corrosive applications, titanium plates can extend the service life. Providing complete medium parameters at the inquiry stage helps suppliers give accurate material solutions and connection dimensions.
The detachable structure of the plate-and-shell heat exchanger facilitates cleaning and the addition or removal of plates, but the design temperature, design pressure, connection standards, and installation space still need to be clarified during selection. Gasket selection must not be replaced arbitrarily; it should be selected from NBR, EPDM, or fluorine rubber according to the medium temperature and chemical properties. Design and selection personnel should specify the medium parameters and material requirements in the technical agreement to reduce on-site changes.
