Plates Cleaning and regasketing, time for Heat Exchangers maintenance

Maintenance is important for a perfect rendition of a Heat Exchanger, in order to prevent interruptions and unplanned production downtime. A Heat exchanger is a thermal equipment used in industrial plants applications such as termostatation, thermoregulation and heat recovery, in order to maintain a constant temperature in manufacturing processes saving on energy consumption. Plate heat exchangers, after a period of service, can develop threads that have to be checked, to assure perfect functionality of the heat exchanger system: working fluids can leave deposits on plates, and some kind of fluids can damage plates themselves, but also gaskets and sealing materials get aged.

First step to avoid problems, is planning a maintenance intervention, cleaning the units of the plant, and controlling the state of plates, gaskets and other components, or also a chemical cleansing removing deposits and dirt that can lower the thermal transfer compromising efficiency of the thermoregulation system. Plates can be cleaned on site (CIP, cleaning in place), for this reason checkable exchangers are the most likely solution, so that’s possible to control them on industrial installation site itself. Otherwise, plates block can be taken to the supplier, who will control it, cleaning if needed and substituting the old plates in the package, if a reconditioning of the system is suitable, redeeming project standard settings.

A periodical maintenance check-up is quicker, faster and more economical. A leak of maintenance can indeed cause, in the long term, severe threads concerning the performances of the overall system increasing energy consumption, and asking for higher operations for the regeneration of the thermal plant. If a serious restriction occurs, a cleaning won’t be enough, and longtime sediments can indeed cause corrosion of plates and components, reaching certain levels of stress that can cause cracking of plates and tubes. The heat exchanger must then be removed to find the blockage, changing eventually damaged parts and components, regasketing and testing the pressure unit. Regeneration of a heat exchanger includes then several operations:

  • complete disassembly
  • old gaskets removal and substitution with new ones
  • plates cleaning and cleansing
  • penetrating liquids test
  • damaged and/or corroded plates substitution
  • trunk regeneration
  • ports arrangement
  • re-assembly with tightening at project standards settings
  • pressure test
  • PED testing if required

There are several indicators signaling a problem in a plate heat exchanger: an issue can be detected by an increase in water temperature and/or pressure, fluid losses and leaks that cannot be stopped by tightening bolts following manual instructions. Also, flow restrictions can be due to a blockage of any nature, and alerting can be an increased length of thermal cycle, a longer workload of the thermoregulating system causing higher energy consumption. In case of problems, do no longer keep the machine operating and call for maintenance, cause using it under non optimal conditions can cause further and more serious issues.

Depending mostly on kind of liquids the plant works with and type of processes it has to serve, it’s possible to better decide when maintenance is suitable. In any case, the best method to find out the most suitable maintenance timing for a heat exchanger is to have monitoring systems added to the plant (manometers and thermometers or a data logger with sensors for a more sophisticated equipment), in order to regularly check operating conditions of it, and taking solutions at the first emerging of any unusual signal, the best way to have a prompt solution preventing incoming problems.

In order to avoid or at least minimize maintenance problems, a key factor is the right choice of materials of the heat exchanger, selecting the most suitable kind of material and the right thickness to avoid corrosion. Design, material and thickness of the plates are key factors to the efficiency of the system. Gaskets and plates material must be compatible with the kind of fluids the system works with and the range of temperatures that they go through during the dissipation process.

To avoid damages to the system, and related stops to the industrial process, a scheduled maintenance plan is suitable, accorded to the characteristic of the thermoregulation system and the industrial processes. So be proactive, a good maintenance plan with scheduled regular visits and check-ups is a cost effective strategy, maintaining constant production levels in manufacturing processes, avoiding costly interruptions and assuring right working condition to operating machines.