The plate heat exchanger is formed by stacking a group of herringbone corrugated metal plates, and the holes on the plate are used for two heat transfer liquids to pass through. The heat exchanger plate is installed in the frame of the fixed plate and movable compression plate, and clamped with bolts. There are sealing gaskets on the heat exchanger plates to guide the fluid to alternately flow into the respective channels. The plate heat exchanger adopts the method of color penetration testing. We will strictly check the cleaned plates to ensure that the plates are free of defects such as cracks and corrosion points like the new ones. The plates after the color penetration test will thoroughly clean the penetrant again. After cleaning, the plates will be quickly and thoroughly dried with compressed air. After cleaning, the surface of the plate will be as clean as new. The cleaned plates will be inspected again and placed neatly.