Sources of Chromium
Chromium is a wear metal found in the coating of parts like valves, rods, rings, and bearings. Typically, increasing levels of chromium, and possibly nickel, disproportional with iron, indicate coating wear, whereas proportional increases suggest steel alloy wear.
One form of proportional chromium and iron increase may arise from non-wearing parts made from stainless steel. Some lube oil piping and/or coolers can be manufactured from stainless steel which may corrode due to elevated acidity, or erode due to particulate. When the ratio of chromium to iron is 1:10 to 1:4, this is highly suggestive of stainless steel wear; when seen with an increase in Acid Number it is likely corrosion, and when seen with an increase in particle count it is likely erosion.
Watch for the next article in the Elemental Spectroscopy blog series: Titanium
