The BR-118 plate heat exchanger is used for medium cooling and heat exchange in chlor-alkali, chemical intermediates, and other sections. On-site operation and maintenance personnel need to implement item by item the corrosion resistance verification of plates and gaskets, the tightening sequence, and leak identification. The following Q&A is organized according to the on-site practical operation sequence.
First confirm the chloride ion concentration, temperature, and pH range in the medium, then compare with the applicable range of the plate material. 304 stainless steel is prone to stress corrosion in media containing chloride ions, so 316L is usually evaluated; when the concentration or temperature is higher, titanium or Hastelloy needs to be evaluated. For gaskets, select grades such as nitrile, EPDM, or fluororubber according to the medium temperature and concentration, and determine spare parts only after item-by-item verification. It is not advisable to directly apply the conditions for normal-temperature clean water.
Tighten evenly in multiple passes in a diagonal sequence, advancing a small amount each time, to avoid deformation of the gasket caused by excessive tightening on one side. Use the clamping dimension marked in the accompanying technical documents as the reference for the compression dimension, and measure simultaneously on both sides. After replacing the gasket, first operate at low pressure for observation, then gradually raise to the design pressure.
Focus on the outer edges of the plate pack, the area near the clamping bolts, and the root of the connecting pipe flanges. When liquid hanging or crystallization traces appear, first record the location and the medium side, then after shutdown and pressure release check whether the gasket at that location has shifted, aged, or has foreign matter remaining in the groove. Internal leakage manifests as mixing of the two media and can be judged with the aid of changes in pressure and temperature on both sides.
Record inlet and outlet temperatures, pressure drop, flow rate, and clamping dimension. When the pressure drop continues to rise, arrange cleaning. Use cleaning agents compatible with the plate material and do not use chlorine-containing cleaning liquids. During shutdown periods, drain the medium to avoid long-term immersion of the gasket.
