Pickling is the chemical removal of oxide layers (scale) and other impurities from steel surfaces prior to subsequent production processes. The acids applied for pickling - mainly hydrochloric acid, sulfuric acid and mixtures of hydrofluoric acid and nitric acid -are highly corrosive. Thus, all components of the pickling line - such as tanks, pipes, valves and regeneration systems - are affected. If material deterioration occurs, acid can be released and may lead to accidents. Non-metallics are preferred choice of material to be used in the process equipment of pickling plants to cope with the aggressive environment of the pickling process. Due to the highly corrosive environments, corrosion also occurs on the plastics equipment. However, relevant corrosion resistance data for plastics are often lacking. This makes it difficult to compare different materials on a price/performance basis and it can sometimes be difficult to give straight forward recommendations for the hot and very corrosive environments found in pickling plants. The use of plastic components without correct corrosion resistance data can be regarded as full scale experiments. Consequently, there is a need for more knowledge on plastic corrosion to improve safety and service reliability in European steel plants.
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