During this time of the year we usually receive many service and maintenance requests for the complete regeneration and revamping of plate heat exchangers. In this case, inspectable type heat exchangers offer the possibility to be opened to proceed with washing and cleaning operations and the inspection of all the parts, in addition to the possibility of an upgrade of the thermal performances.

Let’s then see step-by-step all of the operations we usually do during a heat exchanger regeneration servicing, aimed to restore the efficiency of the exchanger as if it was new.

Very often heat exchangers that come for a revamping are in quite disastrous conditions, after years of functioning. First of all, we open the exchanger in order to inspect the wear status of tie-rods, port linings and gaskets. While doing a complete regeneration of exchangers, we usually suggest customers a complete replacement of the gaskets with a full kit of brand new ones, even if the operation is expensive and invasive, but it is suitable while doing the washing of the plates.

Another operation we usually do, once the plates have been washed and cleaned, is to undergo plates at 100% with an integrity testing using penetrating liquids. It allows to ensure that plates have no micro-holes or hairlines cracks. These could be caused by corrosion, revealing a serious problem of incompatibility of the fluids with the construction material of the plates, or even due to erosion or engendered by a wrong tightening made by the end user. Once the exchanger is reassembled it is indeed complicated to search for possible leaks or mixing.

 

And so, washing of plates, penetrating liquids test and potential discharge of damaged plates. These operations allow to understand if there is any issue of compatibility between the fluids circulating within the exchanger and the material of the plates, alerting the customer.

The exchanger is then re-gasketed, using brand new gaskets, and also potentially damaged port lining – in case of flanged exchangers – and threaded connection ports are replaced. The exchanger is then reassembled, with the attention of replacing the tie-rods, or at least to clean the existing ones. The exchanger gets tightened with the right level, and undergoes a pressure test, aimed to ensure that the two circuits are correctly sealed with no leaks within the exchanger.

Once the pressure test is completed, the plate heat exchanger is ready to be dispatched to the customer. A new label is placed, reporting the date of the revision and complete with all the codes that identify the provided operations.

At last, a further operation we usually offer is to ask the customer if he needs to upgrade the performances of the exchanger in order to meet new requirements of his plant. Is it possible indeed to expand the exchanger, or to make some variations to the design of the plates, giving in fact a brand new life to the plate heat exchanger.

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