Plate heat exchanger–the maintenance of elastic sealing gasket

Plate heat exchanger–the maintenance of elastic sealing gasket


Plate heat exchanger is an important part of the heat exchange technology in process industrial equipment. The elastic sealing gasket, which conducts sealing between various plate thermal sheets, is a kind of vulnerable part, as well as a kind of part prone to aging under natural conditions. The service life of elastic sealing gasket has an important influence on the service life of plate heat exchanger. If the sealing gasket hardens and loses the original elasticity, the heat exchanger will not function properly.
The softening of elastic sealing gasket is related to pressure and temperature. When the sealing gasket loses its elasticity, the heat exchanger will leak through. For some products, in order to avoid the leakage phenomenon caused by aging of the gasket, the sealing property of the heat exchanger is allowed to be adjusted, namely, screwing up the bolt of the combined plate heat exchanger again, and adjusting the pressing force of the elastic sealing gaskets between the heat exchangers, thus solving the problem of leakage. The maximum and minimum allowable stresses are generally marked on the nameplate of heat exchangers with the above function. For new heat exchanger sheet group, the minimum allowable stress should be used for connection and fixation. According to the number of heat exchanger sheets in each group, the tightening force of the heat exchanger can be adjusted once or for multiple times. Every time when screwing up, the nut can be 3mm screwed in, and the stress of the adjustment sheet should always be noted, besides, it is only allowable to adjust the tightening force of heat exchanger without working pressure at room temperature, so as to prevent leakage.
For plate heat exchangers without stress adjustment range marked on the nameplate, generally the stress values are marked in the parts drawing. When screwing up the above plate heat exchangers, the tightening torque in any case should not be less than the numerical value stipulated in the drawing, as it is related to the assembly quality and assembly deformation of plate heat exchangers. When the tightening torque reaches the required numerical value, the elastic sealing gasket can be replaced designedly. For plate heat exchangers used in important production equipment and corrosive medium, it is recommended to prepare a set of spare sealing elements. When the warehouse temperature is 18 ℃, the sealing elements of plate heat exchangers can be stored for about 3 years in transparent plastic package.

In principle, the fixation of sealing elements is divided into adhesive fixation and non-adhesive fixation. The shape of the sealing gasket should be consistent with that of the sealing site of the plate heat exchanger. It must be noted that the adhesive fixation method will not affect the sealing function.
1. Non-adhesive sealing
(1)Align: put the sealing ring in place
(2) Put in: make the sealing ring exactly get into the seal groove
(3) Compress: the seal groove has a groove shape structure with gradually decreasing cross section, so that the sealing ring can be rightly positioned.
2. Adhesive sealing
According to the use purpose of the sealing gasket and the sealing quality requirements, harmonic sealant and non-harmonic sealant produced by different manufacturers can be optional. Before adhesion, steam flow should be used to thoroughly clean up the residual adhesives and residual gasket on the adhesive surface. For adhesion with harmonic sealant, the residual adhesives and residual gasket on junction surface of the plate heat exchanger must be burned out with fire. For large-batch adhesion, liquid nitrogen pool for freezing sealing elements and heating furnace for drying the plate heat exchanger with sealing gasket should be prepared, and the heating temperature should reach 160 ℃. If conditions permit, chemical cleaning should be done on the heat exchanger to ensure complete removal of residual adhesives on junction surface of the plate heat exchanger. Whether the sealing gasket is installed properly can be learnt through the nest peep hole of the plate heat exchanger.

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