For the production of cans in the food industry, especially surface treated tin plate is used. For the surface treatment, the tin plate is dipped in a hot bath with concentrated chromic acid and other additive chemicals. Due to the extremely aggressive liquid an adequate corrosion protection of the plant components is necessary.
ECTFE for corrosion protection
Thanks to the corrosion experts at AGRU Kunststofftechnik (Austria) it was confirmed that ECTFE will withstand these harsh conditions in the chromic acid bath. Combined with the know-how of the team of AGRU Technology (Thailand) Co., Ltd. a solution was worked out to install 2.3 mm ECTFE fabric backed sheets in the existing tanks. Specifically the AGRU ECTFE SK+ fabric backed sheets were selected because the acid resistant SK+ fabric is the preferred solution in applications with acids. Starting from 2017 already several components were lined with the ECTFE sheets and successfully put into operation.
Proven advantages of ECTFE
In the past the bath for the chromic acid were made from rubber lined steel. Experience showed that the rubber lining is not fully resistant to chromic acid. This resulted in a lot of maintenance and repair work that led to reduced machine availability. A huge problem from the rubber lining was also that rubber particles were washed into the chromic acid and this led to undesirable deposits on the surface of the tin plate which resulted in rejected products. On the other hand the ECTFE sheet lining now provides a long-term solution. Additionally the client reported that the ECTFE surface is much easier to clean than previously used solutions.
