Cleaner steels meet demands for high purity process systems
Cleaner steels meet demands for high purity process systems
Keywords Cleanliness, Sandvik, Steel
New and "cleaner" grades of steel, used in the manufacture of electropolished tubes and fittings for high purity gas distribution systems, have been added to the range now available from Swedish tubes and fittings producer, AB Sandvik Calamo.
The grades, designated Sandvik 2R68 and Sandvik 2R68 AOC-VAR, are a molybdenum-alloyed austenitic chromium steel, characterised by low contents of manganese, sulphur, carbon and nitrogen. Specially developed for applications where high demands are made on the allowed limits of contamination, such as carrying ultra-clean gases and liquids in the semiconductor and pharmaceutical industries, Sandvik 2R68 claims improved cleanliness with low non-metallic inclusions.
An even cleaner grade,Sandvik 2R68 AOC-VAR, with exceptionally low inclusion levels, is available through a double melting, vacuum arc remelting process.
As a result, when Sandvik 2R68 or Sandvik 2R68 AOC-VAR steel grades are used in the production of electrolytically polished tubes and fittings, there is believed to be much less risk of contamination of the transported media. Other benefits claimed of the new grades are good weldability and corrosion resistance. The Sandvik 2R68 grades are a highly alloyed stainless steel which, together with very low levels of impurities and an electropolished surface, combine to have a positive effect on corrosion resistance. The grades exhibit improved resistance to both general and localised corrosion compared with standard stainless AISI 316L materials.
Particular resistance to pitting and crevice corrosion improves with increasing molybdenum content and fewer impurities. Sandvik 2R68 grades, with about 2.6 per cent molybdenum, have higher resistance to attack than standard stainless steel types AISI 304L/316 and 316L.
Further details available from: Sandvik Steel, UK. Tel: +44 (0) 121 504 5100; Fax: +44 (0) 121 504 5151.
