Corrosion protection test
Year of publication: 2006
With the Petrotest device, OELCHECK tests the corrosion protection behavior of oils according to DIN ISO 7120. The test procedure was developed for mineral oils and other liquids such as synthetic oils. The test is used to assess the extent to which corrosive attack occurs on iron components in the presence of water and whether the corrosion-preventing additives can still reliably stop rust formation in used oils.
The oils tested are primarily inhibited mineral and synthetic oils, i.e. those with corrosion protection additives, such as those used in steam turbines, recirculating lubrication systems or hydraulic systems.
Table of contents
The testing procedure
Whether passed or not – the statements in the OELCHECK laboratory report are unambiguous:
- Passed:
No corrosion - Failed:
The degree of corrosion is indicated as follows:
- Light rust: Fewer than six spots, each no more than 1 mm in diameter
- Moderate rust: Less than 5% of the surface of the test specimen showing rust
- Heavy rust: More than 5% of the surface of the test specimen shows rust
If the test is not passed, the corresponding oil will not be able to prevent corrosion of ferrous components, especially in the presence of water, even in practical use. In this case, the oil should be changed as soon as possible. If the other oil values are not of concern, post-additivation could be considered with the oil manufacturer's engineers for turbine oil fillings of several tens of thousands of liters.
The OELCHECK analysis kit for turbine oils (VGB)
Corrosion protection plays a very decisive role, especially in turbine oils. Therefore, the corrosion protection test is an integral part of the OELCHECK analysis set "VGB" for turbine oils. The selection of tests corresponds to the guidelines developed by the DIN 51515 working group. The description of the test procedures and limit values for used turbine oils are published in a separate VGB sheet.
The scope of analysis of the "VGB" analysis set includes:
- Atomic emission spectroscopy for the determination of wear metals, additives, impurities (over 20 elements).
- PQ index
- Oxidation
- Phenolic oxidation inhibitors in % of fresh oil
- Viscosity at 40 and 100 °C and viscosity index
- Visual evaluation
- ASTM color number
- Density
- Neutralization number
- Water content based on Karl Fischer
- RULER for determination of antioxidants
- Particle counting & purity classes
- Air release properties
- Water separability
- Foam tendency - Sequence I
- Corrosion prevention (steel)
"Scaled down" analysis kits with a smaller test scope are also available.
