1, before assembly plate sealing groove processing
Before gasket assembly, check whether there is any foreign body in the sealing groove of the plate. If there is any foreign body, remove it in time before gasket assembly.If the burr has appeared around the plate sealing groove in the pressing process, it should be removed by 0 sandpaper, or it can be removed by polishing machine.
Both non-stick gaskets and bonded gaskets should be cleaned of oil and burrs on the surface of the plate before assembly.Removal of oil pollution can be used 10%~20% of the alkali solution in more than 70C water immersion
With the method of 8h, it is more ideal to use the dynamic circulation of alkaline water under the conditions. The time of the sample plate resting in alkaline water can be reduced by half. After that, the plate will be washed clean with flowing water until the cleaning liquid is completely discharged.It should be noted that under any circumstances, it is not allowed to use hydrochloric acid to clean stainless steel plates. When preparing cleaning solution, the mass concentration of chloride ion in water shall not exceed 30mg/L.
2, the correct choice of adhesive
Correct selection of adhesive varieties, models, to ensure that the gasket stick firmly.The curing time of adhesives containing low or no benzene should not be less than 24 hours.In addition, attention should also be paid to the environment where the gasket is pasted. If the humidity at the assembly site is too large, the curing time should be appropriately extended or the humidity at the assembly site should be reduced.
If the non-stick gasket is used, when the gasket is too long or too short, the adhesive should be added to the appropriate parts of the second seal and the straight strip.When the local point adhesive is used for the non-stick gasket, it should be noted that the point adhesive also needs to have a certain curing time.
Under normal circumstances, the edge width of the plate sealing groove is about 10mm and the width is consistent, but in the actual pressing process of the plate, the width of the plate cutting edge is often inconsistent, and the daily error will be large.If the cutting edge of the plate is too wide, it will lead to the non-stick gasket can not be fully into the groove, and it will be offset to the outside of the sealing groove, which will seriously affect the sealing effect.
Adhesives with no or low chloride ion content should be selected to ensure curing time.Ensure the outer width of the plate sealing groove during the plate fabrication process.
3. Prevent secondary pollution on the surface of gaskets in advance
The secondary contamination on the gasket surface and the impurities mixed in the gasket can also cause the early seal failure of the heat exchanger.The surface pollution of gasket is caused by human, and the surface pollution of gasket is caused by the repeated use of vulcanized die in the process of gasket manufacturing.Mold made of Q235 steel and 45 steel, under high temperature conditions for a long time, the mold cavity will produce oxidation phenomenon, so that the mold cavity pollution, resulting in gasket surface pollution.In this case, gasket production can be appropriate to use some rubber release agent.
The release agent can solve the gasket contamination caused by high temperature oxidation of the mold cavity, but the release agent itself will cause some re-contamination to the surface of the gasket.
The appearance quality of the gasket surface is improved, but the smoothness of the gasket surface is increased, and the possibility of slip between the gasket machine and the clamped plate and the gasket is also increased, which becomes a hidden trouble affecting the sealing and bearing effect.
Rubber in the process of mixing out of type processing to be used due to management loopholes and careless can make the mixing rubber mixed with a small amount of impurities difficult to distinguish with the naked eye, when this situation exists, the gasket after vulcanization molding is easy to be fractured in the impurities after installation, resulting in the whole equipment
Early seal failure is also one of the reasons for assembly failure.In order to prevent the surface contamination of gaskets, it is necessary to strengthen the cleaning of the die cavity during the manufacturing process of gaskets and increase the cleaning frequency of the die.An appropriate amount of sprout preventer is added to the rubber formula for gasket manufacturing to prevent low-molecular substance from ejecting.
In addition, when the pressure test, the pressure test of the plate heat exchanger, which requires higher pressure capacity, should adopt the method of step pressure boost and stage pressure holding.Stepped pressure boost and phased pressure retention can accurately reflect the overall performance of the plate heat exchanger.If the stepped-type pressure boost and phased pressure holding process are omitted and the pressure is directly increased to the design pressure, the pressure boost speed should be eliminated to reach the pressure bearing capacity.
Plate heat exchanger pressure test seal failure is a complicated problem, in the process of design, manufacture, installation, every detail and every parts problems may lead to seal failure, so in front of the machine to seal failure that may occur and occur the potential for effective prevention and control, strengthen the inspection of parts, eliminate quality hidden trouble.
