A high metal is an investigation trigger—not a component diagnosis.
Map the element to actual equipment metallurgy, normalise for service interval and make-up oil, check particle-size limitations, then look for an independent signal that predicts the same mechanism.
Sample, units, method, interval, top-up and baseline.
Which wetted components contain the element?
PQ, ferrography, particles, companion metals and machine data.
Protect the asset, inspect the likely source and resample.
What to check when a metal is high.
Sources vary by machine design and oil formulation. Always compare with new oil, component metallurgy and maintenance history.
| Element | Common sources | Corroborate with | First actions | Escalate when |
|---|---|---|---|---|
| Iron (Fe) | Gears, shafts, liners, rings, rolling bearings, rust | PQ index, ferrography, chromium, silicon, particle count and filter debris | Verify rate per service interval; inspect filtration and magnetic debris; identify the iron-bearing component from equipment metallurgy. | Iron rises rapidly, PQ/large debris also rises, or vibration/temperature corroborates active wear. |
| Copper (Cu) | Bushings, bronze bearings, thrust washers, oil coolers and some additives | Lead, tin, iron, coolant markers, oil age and ferrography | Confirm new-oil copper and cooler metallurgy; review bearing load and oil-cooler history. | Copper rises with lead/tin, debris morphology or bearing symptoms. |
| Aluminium (Al) | Pistons, housings, thrust bearings, pumps; also airborne dirt with silicon | Silicon, iron, chromium, particle count and component metallurgy | Inspect air induction, seals and filters; distinguish abrasive dirt from aluminium-component wear. | Aluminium and silicon/iron rise together or piston/pump symptoms appear. |
| Chromium (Cr) | Chrome-plated rings, liners, shafts, bearings and stainless components | Iron, nickel, PQ, ferrography, compression and blow-by evidence | Review plated component metallurgy and operating load; confirm with wear-particle evidence. | Chromium rises with iron, oil consumption, loss of compression or large debris. |
| Lead (Pb) | Bearing overlays, solder and legacy component materials | Copper, tin, iron, oil pressure and ferrography | Confirm bearing metallurgy and exclude fuel/additive sources; review load and lubrication pressure. | Lead rises with copper/tin or bearing distress indicators. |
| Tin (Sn) | Bearing overlays, bronze alloys and solder | Copper, lead, iron, PQ and bearing operating data | Identify tin-bearing parts and inspect bearing-related trends. | Tin rises with copper/lead, PQ or abnormal bearing temperature. |
| Nickel (Ni) | Alloy steels, valves, turbine components and nickel-plated parts | Iron, chromium, component metallurgy and ferrography | Map nickel-bearing components and compare trend after overhaul or material change. | Nickel rises with related alloy metals or machine symptoms. |
| Silicon (Si) | Airborne dirt, sealants, silicone grease, coolant inhibitors and antifoam additives | Aluminium, iron, particle count, filter debris and recent maintenance | Inspect breathers, air intake, seals and transfer practices; verify new-oil/additive baseline. | Silicon rises with aluminium/iron or cleanliness deteriorates. |
| Sodium / Potassium | Coolant inhibitors, seawater/salt, process contamination and some additives | Glycol, water, boron, coolant pressure and new-oil chemistry | Do not diagnose coolant leakage from one element; verify additive baseline and run coolant-contamination tests. | Multiple coolant markers agree or water/viscosity changes create lubrication risk. |
Particle size changes the evidence.
Routine ICP methods respond mainly to dissolved and fine particulate material. Large abnormal wear particles may produce a modest elemental result. Pair spectroscopy with PQ index, ferrography, filter-debris inspection or other particle-sensitive methods when severe wear is plausible.
Oil consumption and interval change the number.
A longer interval can accumulate more metal; high make-up can dilute it. Sump size, filtration and oil loss also alter concentration. Compare rate per hour only when sampling and operating context are reasonably stable.