Corrosion and scaling in mould forms PET bottle cooling system

Company: Coca Cola H.B.C. AG, Thessaloniki
Responsible: Mr Tsoutsas and Mr. Kouroglou

Description of the problem and its negative consequences

The client uses a closed loop for cooling down the mould forms for his production of PET bottles. The water is cooled by a plate heatexchanger. Due to a little leaking of the loop, there has constantly added some fresh water to this loop. Through this fresh water, all the time was added some lime scale as well as new oxygen in the loop. This causes all time new corrosion, and the loop has to be cleaned in average all 14 days. Mostly from rust and a little scale. This leads to significant cost, not only the cleaning and the used chemicals, but even more the closedown of the production for several hours. This cleaning was not always possible in time, and this leads to serious quality problems at the bottles itself.

Our solution

We installed one Merus®-Ring in the cooling loop. In between the heatexchanger and the moulds at the machine. It was installed very near to the mould forms, in order to get the best possible results in the forms.

In which way our customer checked the results of the trial

1. Starting at the day of installation of Merus, there were made daily samples of the water, which was checked for the iron content of the water by the companys own labor. In a totally closed loop it was to be expected, that the iron content in the water would increase, due to solving of the existing rust in the pipes and the mould forms. But due to the small leackage, the rust and the scale was drained from the system as well. So it could bee seen, that the iron content in the water decreased steadily and stabilized on a very low and acceptable value.
2. Since that it could be seen by several inspections by sight, that there was no corrosion or lime scale in the mould forms at all. As well there was since this time no need of chemical cleaning. The big advantage for the client, not only that the quality of the PET bottles is constantly high, there is as well no need for a break down of the production which saves a lot of money.