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Description

In response to a manufacturer’s notification, a midstream company conducted an exposure assessment of hexavalent chromium in a previously unidentified location. This assessment identified the need for controls to prevent overexposure.

Chromium present in stainless steel may form as a residue on the exterior and sometimes interior engine or turbine components. This chromium is hexavalent (Cr6+ ), which is a carcinogen and a skin and respiratory sensitizer. It forms when metal in an oxidizing or corrosive environment is in contact with calcium oxidecontaining materials, such as thread sealants or insulation. The generation of Cr6+ increases at elevated temperatures and often appears as a yellow or white residue on engine components and adjacent insulation surfaces.

  • The presence of this residue and how it is produced was not known until the last few years.
  • The residue may often be mistaken for sulfur and can be difficult to see with typical sodium lights.
  • Exposure may occur if the residue is disturbed during tasks such as sampling, maintenance activities, or hot work like grinding and welding.
  • Routes of exposure include inhalation, skin contact and ingestion.
  • Cr6+ has very low airborne exposure limits such as 0.0002 mg/m3 or 0.01 mg/m3 , depending on the jurisdiction.

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