Maintenance and Repair Overview
In the many applications of heat exchangers, it is not possible to specify the exact time interval for maintenance. As needed, the following repairs and adjustments must be performed. If there is leakage, the device must be re-tightened. If the device still leaks after re-tightening, other causes must be investigated. If the device has already been tightened to the last heat dissipation plate and the leakage cannot be stopped, the gaskets must be replaced. Connecting rods and the contact surfaces between lock nuts and the central radiator plate must be greased. If heat capacity decreases or pressure loss increases, the heat exchanger must be cleaned.
Cleaning-in-Place (CIP) Procedures
When cleaning radiator plates in place, the product is replaced with a cleaning solution. To achieve the best cleaning effect, the cleaning solution should be pumped through the device in the direction opposite to the usual product flow. Increasing the flow rate of the cleaning solution ensures a better cleaning effect. By adding compressed air, the flow rate of the cleaning solution in the device can be further increased for better cleaning results.
Before cleaning, verify whether the cleaning agent is suitable for the radiator, connectors, gasket materials, and gasket adhesive. The specific cleaning substances, dosage, and process duration depend on the type of materials used and the type of deposits to be removed. Contact the cleaning agent manufacturer for recommendations. Certified cleaning and disinfecting agents include sodium hydroxide-based alkaline cleaners up to 5 percent concentration at temperatures up to 90 degrees, phosphoric acid-based acidic cleaners up to 5 percent, and peracid or hydrogen peroxide-based disinfectants up to 1 percent at 20 degrees. Hot water at up to 120 degrees can also be used for thermal sanitization.
Gasket Inspection and Replacement
Through visual inspection, gasket deformation, improper installation, or damage can be easily observed. To test gasket function, a single-side closed-circuit pressure test can be performed. If the leakage groove is not deformed or blocked by dirt, and there is no external leakage during the single-side closed-circuit pressure test, the gasket function is normal. As long as the device has not been tightened to the last plate and gaskets have not suffered thermal, mechanical, or aging-related damage, very small dripping leaks can be repaired simply by re-tightening.
If leakage is not eliminated after re-tightening, other causes must be investigated. The gaskets must be checked for positioning or damage. To replace gaskets, simply open the heat exchanger without moving the radiator plates. Check whether there is dirt on or under the gasket, as well as in the exchange plate gasket groove. After long-term use, not only the gasket at the leak location but also all other gaskets should be replaced.
Troubleshooting Common Issues
External Leakage: Causes include heat exchange plate corrosion from chloride action, plate deformation from pressure shocks, gasket aging at end of service life, or gasket hardening and swelling from insufficient chemical resistance. Solutions involve replacing affected plates or gaskets and using more resistant materials.
Product Mixing: Internal leakage between product streams can occur from plate rupture due to pressure changes or chemical action. Thicken plates or use more resistant materials. Check connectors for damage from pipeline stress.
Performance Problems: Dirt in plate gaps from particles, fibers, or bacteria reduces heat exchange efficiency. Clean the device and consider using filters on inlet streams. Changes in operating conditions may require adjusting the plate arrangement or plate type.
