Four main reasons for external leakage:

1. Tightening not in place, uneven size everywhere (the size deviation should not be greater than 3mm) or loose tightening bolts.

2. Part of the gaskets are out of the seal slot, the main sealing surface of the gasket is dirty, the gasket is damaged or aging.

3. The plates were deformed and the assembly was misplaced.

4. There are cracks in the part of the plate sealing trough or in the leakage groove areas.

Methods for leakage in plate heat exchangers:

1. In the state of unpressure, retighten the equipment according to the tightening size provided by the manufacturer, the dimensions should be uniform and consistent, the deviation of the tightening size should not be greater than ± 0.2 N (mm) (N is the total number of sheets), and the parallel between the two tightening plates should be maintained within 2 mm.

2. Mark the external leakage area, then detach the heat exchanger and examine it from one place to another, then reassemble or replace the gasket and plate.

3. Detach the heat exchanger, repair the deformed part of the plate or replace the plate. When spare parts for plates are not available, the plates at the deformed part can be temporarily removed and reassembled for use.

4. When reassembling the disassembled plate, the surface should be cleaned to prevent dirt from adhering to the sealing surface of the gasket.

Causes of internal leakage

a. Due to improper selection of plates, the plates are corroded, cracks or perforated;

b. The operating conditions do not meet the design requirements;

c. Stress corrosion caused by residual stress after cold stamping and forming of plates and too small clamping size in assembly;

d. There is a slight leakage at the leakage groove of the d-plate, which causes the harmful substances in the medium to concentrate and corrode the plate, forming internal leakage.

Solution:

a. Replace cracked or perforated plates, and find cracks in the plates by light transmission method on site;

b. Adjust the operating parameters to make them meet the design conditions;

c. The clamping size of the heat exchanger should meet the requirements when it is repaired and assembled, and it is not as small as possible;

d. Choose correct plate material.