Inhibition of Pitting Corrosion in 316L Stainless steel: an evaluation of the phenomena and method to facilitate material selection for processing equipment

Sammanfattning

This master’s thesis is written for Tetra Pak with the aim to investigate if pitting corrosion inhibition can be detected for Stainless Steel 316L in contact with dairy products in an experimental setup. The aim was also to continue developing a corrosion test method to facilitate for material selection of food pro- cessing equipment in order to reduce the extent of detrimental pitting corrosion. The experimental work was conducted with the help of the department of Production and Materials Engineering at Lund Univer- sity. A corrosion testing machine was utilized in order to follow the corrosion of the SS 316L samples. The corrosion testing routine was modified to suit food processing conditions with modifications to the sample preparation and the implementation of a cleaning in place (CIP) routine to combat fouling and biofilm-growth in the machine. Pitting corrosion of SS 316L was inhibited by the presence of dairy in the electrolyte for all assessed parameters except for the salt concentration 100 000 ppm (10wt%). The results can provide insight into the material selection of food processing equipment if compared to real- life pitting corrosion and industry knowledge. The method shows great promise to utilize in testing novel food products in which the industry lacks knowledge and make informed material choices of processing equipment. Necessary developments to further use the method is to eliminate crevice corrosion and alter the electrochemical measurements to suit the operating conditions.