Plate Heat Exchanger Maintenance
In this article, we look at the importance of plate heat exchanger maintenance, the causes of wear and tear, what good maintenance involves, timeframes and procedures, how to prevent damage, and more!
Importance of Plate Heat Exchanger Maintenance
Some types of plate heat exchangers require maintenance sooner than others, depending on their design, their system application, and the materials involved. However, every heat exchanger will eventually wear out sooner or later, and maintenance, repair, or in worst case – complete replacement will be required!
A plate heat exchanger requires ongoing maintenance to ensure it runs efficiently and gives best performance. If you stop servicing your vehicle, for example, you run the risk of mechanical problems and causing possible safety hazards. If a plate heat exchanger is not properly maintained, there is a risk of fouling, corrosion, leakage or other more serious damage occurring. These types of damage will without doubt significantly reduce the performance of the plate heat exchanger and potentially create serious issues in some Food & Hygiene applications.
Another reason why plate heat exchanger maintenance is important, is to help avoid emergency repairs. For example, if a plate heat exchanger stops functioning in many applications, the entire process comes to a grinding halt. In a Heating, Ventilation, and Air Conditioning (HVAC) situation this can be a disastrous outcome for the company’s productivity, and ultimately cause very expensive emergency repairs for replacement components, which in a lot of cases are rarely ex-stock in Australia and are often made to order.
Some Causes of Heat Exchanger Wear and Tear
Fouling is a build-up of unwanted materials on a plate heat exchanging surface. The sediment or encrustation insulates critical heat transfer surfaces, reducing the rate at which heat can be transferred through them. Therefore, this reduces the efficiency of the whole heat transfer process.
Some examples of plate heat exchangers where severe fouling has occurred:
Erosion happens where the flow of the fluid passes through the plates and wears away the plate surface. This effect can be exacerbated by the presence of particles, such as sand or silt in the fluid, which can remove material at a much faster rate. This then leads to the plate wall thinning and creating leak paths, with potential cross-over of media. Plate on Plate contact and rubbing together also causes opportunity for degradation and thinning of plate materials.
Coolants and other mediums can corrode the metals in a plate heat exchanger, which damages them over time and leads to residues that clog the heat pipes. Coolants can also wear down the surface of the plates, thinning the material over time.
Some environments can cause heat exchangers to get dirty faster. For example, this is seen in applications that involve exhaust gases, like in marine charger coolers. An environment with lots of dust and carbon build ups causing problems for heat transfer.
Gasket failure is a common form of Plate Heat Exchanger leakage. This can be caused by gasket failure due to exposure from process activity by either excessive heat or by process chemical attack. Over time gasket materials can also become compression set, losing their compressibility and sealing ability. Gasket failures are common and often lead to excessive leakage of medias externally to the plate heat exchanger location.
This image shows a large Plate Heat Exchanger with total gasket failure – seen at overhaul, the unit was offline for several weeks:
This image is an example of what happens when severe heat exposure has caused complete plate fracture:
Good Heat Exchanger Maintenance
To maintain a plate heat exchanger, it is important to keep the plate surfaces clean and to regularly check that the unit is operating as it should. Where fouling is expected, the plate heat exchanger should be designed with set maintenance procedures in mind, and the cleaning method for the unit must be compatible with the heat exchanger plate & gasket material and the medias involved.
Standard Maintenance Activities
There are a number of best practice activities that can be carried out by the site maintenance team, for example:
- Alternate duty and stand-by Rotation (this is where the plant has redundancy with a second plate heat exchanger)
- Maintain control and analysis of chemical dosing and water quality
- Conduct regular checks that any filtration systems are working correctly and are not blocked thereby reducing the risk of foreign objects getting inside
- Ensure that each plate heat exchanger is performing as expected, and there are no unusual temperature or flow issues
- Have an open & inspect regime at regular intervals – it is best to have it inspected by an expert to avoid more significant issues
For optimum plate heat exchanger performance – Thornhill Australia can assist you with our factory and on-site servicing, and testing methods that include gas integrity testing and clean and crack test services.
Servicing Time Frames
Plate Heat Exchangers should be serviced regularly, all dependant on site application and service history, at a time somewhere between 6 monthly intervals and to a maximum 4-year timeframe, obviously depending on their working environment. For instance, hydrogen coolers in power stations may go 4 years between inspections. However, where scaling, or potential fouling is a factor, then a plate heat exchanger might need cleaning every 6 months.
Usual maintenance begins at an ‘open and inspect’ analysis around 12 months from the initial operation. Any trending towards wear or symptoms of problems, such as scaling, can be analysed and determined then, with appropriate intervals scheduled for maintenance thereafter.
The following photo was taken 4 years after original installation – the elastomer has become compression set and hardened:
Maintenance Time Frames & Procedures
Standard heat exchanger maintenance or repair activities usually take anywhere between 1-2 days and up to a week depending on plate condition, and size of the unit. However, larger installations or more complex repairs take longer, and without prior ordering of spare replacement components, the unit can be out while manufacture and shipping of plate and gasket occurs. This can be anywhere between a 3–10-week delay and outage.
On-Site Maintenance Procedure
For on-site servicing, Thornhill Australia offers a complete turnkey service, quality parts, and dedicated and experienced technicians with the technical knowledge to deliver your project.
On-site servicing includes the installation of plates and gaskets, Cleaning In Place (CIP) systems, and different testing services such as Gas Integrity Testing, Holding Time Tube Testing, and Hydrostatic Testing.
Factory Maintenance Procedure
Thornhill Australia factory services, will bring the plate heat exchanger unit back up to maintenance requirements by removing and sending each plate pack to one of our Service Facilities.
It’s here that each plate will be individually cleaned, inspected for damage, and crack tested, before returning to site for installation and final testing.
We ask that you please allow gasket manufacturers lead time and shipping before schedule can commence; for the larger units, please allow 3-5 days before the plate pack is gasketed and re-assembled for return to site for installation.
Maintenance or repair also provides an opportunity to change the design or make another type of upgrade, such as making the heat exchanger more efficient. Thornhill Australia may be able to upgrade the heat exchanger so that it lasts longer or performs better and is more efficient.
Thornhill Australia’s on-site servicing maintenance sequence involves:
- Attend site and complete Safe Work Method Statements (SWMS) and isolations
- Remove plate pack
- Ship to Thornhill Service Facility
- Inspect all plates and gaskets
- Refurbish plate pack as required including:
- Chemical cleaning
- Crack detection
- Visual Inspection
- Regasketting (glue or clip)
- Return to site with sequenced plate pack
- Install plate pack and retest / test run
- Issue full report on findings and issue test certificate
Our report incorporates photos and a description of any issues, and if known, we will also include some history on the unit. We then report on the condition of the equipment, and any recommendations for future maintenance.
Heat Exchanger Warranties
All New Plate Heat Exchanger warranties are covered for 12 months service under normal and general Terms & Conditions of supply.
Gasket & Plate warranties are also covered from 12 months after installation.
Preventing Heat Exchanger Damage
Companies can mitigate heat exchanger wear and tear and reduce the need for costly repairs by:
- Regular checks by your company for unusual activity
- Regular maintenance activities and services from our Thornhill Australia team, including an open and inspect schedule
- Completing our online enquiry form and asking about our Service Contracts to ensure you’re getting the best service for your business.
- A customised maintenance plan helps to keep your facility running stress-free with the knowledge you have full back support from our expert service team