Wilmar’s experience with hexavalent chromium

In April 2019, Siemens, one of Wilmar’s turbine suppliers, released an Urgent Technical Advisory Service Bulletin to its customers to advise that Siemens had undertaken trials in which some anti-seize pastes applied to certain steam turbine components exposed to temperatures of above 400 °C may lead to the production of a residue of hexavalent chromium (Cr (VI)) on the components. Cr (VI) is a recognised human carcinogen and a regulated waste by governmental and health authorities. Cr (VI) compounds are often brightly coloured yellow, a physical characteristic that has assisted identification. Wilmar recognised a requirement to develop procedures for safe removal of Cr (VI) as this contaminant could be uncovered when undertaking future maintenance on turbines or boilers. This paper presents the likely Cr (VI) growth mechanism, locations where Cr (VI) has been found so far at Wilmar sites, Wilmar’s management procedure for Cr (VI) identification and for decontamination, and what is being done to better manage formation of Cr (VI) residues during operation of the steam plant.