VDEh-Industrial Researching Institute (Düsseldorf, Germany):

Rögener F., Dr. Eng., Project Group Head, frank.roegener@bfi.de
Sartor M., Dr. Eng., Project Head
Reichardt T., Mag. Eng., Head of Technological Equipment, Coating and Tribotechnics

Swerea KIMAB (Kista, Sweden)

Bergsjö P., Dr., Chief Engineer
Römhild S., Dr., Project Head

The reliability of plant components made of polymers makes a signifi cant contribution in the steel industry to the effi ciency of pickling lines, as well as to occupational safety and environmental protection. Owing to their stability against the highly aggressive pickling acids, polymers have been employed successfully for decades as material for tanks, pipes, valves and acid regeneration technology. Stability of polymer (PP) against mixed acid as a function of the production process (extrusion/die casting). Damage of a PP pipe (mixed acid, 40 ºC) is shown, as well as welding problems during maintenance and delamination of a fibre-reinforced PVDF liner at a packing column for mixed acid recovery. Most commonly plastics as well as composite materials are used. But, when in contact with pickling acids, even these supposedly acid-resistant materials show phenomena such as degradation, swelling, stress cracking or acid diffusion, which can be also called „Plastic corrosion“. Typical pickling conditions for carbon dteel and stainless steel are presented. Activities for the assurance of safe polymer handling in pickling lines is formulated. Therefore, there is a strong need in the steel industry for increased knowledge on the use of polymers in pickling plants.

1. Fitzpatrick, T. L.: Old pickling lines get new life with plastic tanks, Proc. AISTech 2009 Iron and Steel Technology Conf., Vol. II, 4.–7. Mai 2009, St. Louis, USA, S. 161/65.
2. Sartor, M.; Buchloh, D.; Rögener, F.; Reichardt, T.: stahl u. eisen 130 (2010) Nr. 11, S. SP70/73.
3. Abts, G.: Kunststoff-Wissen für Einsteiger, Carl Hanser Verlag, München 2010.
4. Bergman, G.: The corrosion approach to create confidence and to obtain reliability and cost-effectiveness of FRP structures, Project report C 2006:2, KIMAB, 2006.
5. Kunststoff rohrverband e. V. KRV [Hrsg.]: Kunststoffrohre in der Industrie — Die richtige Wahl, www.krv.de/images/stories/docs/publikationen/Industriebroschuere.pdf
6. Schüßler, S.: Chem. Eng. (2010) Nr. 9, S. 32/36.
7. Kramer, E.: Kunststoffe, Synthetics (2004) Nr. 9, S. 21/24.
8. Gomez, J.: CAV (2011) Nr. 3, S. 55/57.
9. Jacobson, K.: Thermoplastic materials in contact with strong acids used in pickling applications, 3^rd Conf. Plastic Materials in Plant Engineering, 7.–8. März 2012, München. 
10. Bergsjö, P.: Experiences and observations of repairs and welds made in process equipment after some time in service, ibid. 
11. Römhild, S.; Bergsjö, P.; Samuelsson, J.; Jacobson, K.; Bergman, G.: The use of FRP in pickling equipment — Experience, state-ofthe-art and new findings, 7^th Conf. FRP Unlimited — Experience and developments with Fibre Reinforced Plastics in industrial applications, 23.–24. März 2011, Fürstenfeldbruck.
12. Plant, L.: Rolling mill risk assessment — a structured methodology to assess vulnerability to major asset failure, Proc. 5^th European Rolling Conf., London, Großbritannien, 23.–25. Juni 2009, S. 1/16. 
13. DSV-Richtlinie 2212-1: Prüfung von Kunststoffschweißern — Prüfgruppen I u. II.
14. DIN EN 13067: Kunststoffschweißpersonal — Anerkennungsprüfung von Schweißern — Thermoplastische Schweißverbindungen.