ASTM D4310 Method for Sludging and Corrosion Tendencies of Inhibited Mineral Oils
4. Summary of Test Method
4.1 An oil sample is contacted with oxygen in the presence of water and an iron-copper catalyst at 95°C for 1000 h. The weight of insoluble material is determined gravimetrically by filtration of the oxidation tube contents through 5-µm pore size filter disks. The total amount of copper in the oil, water, and sludge phases is also determined for Procedure A. Procedure B requires the sludge determination. The copper determination is not required. The acid number determination is optional for both procedures.
NOTE 2 - Optionally, some operators may choose to: (1) assess the change in weight of the catalyst coil, or (2) determine the acid number at 1000 h, or both. The acid number may serve as a criterion to determine if measurement of insoluble material is warranted. Normally, further testing is not recommended on a highly oxidized oil (that is an oil which has attained an acid number >2.0 mg KOH/g). Instructions for these optional tests are not included in this test method.
5. Significance and Use
5.1 Insoluble material may form in oils that are subjected to oxidizing conditions.
5.2 Significant formation of oil insolubles or metal corrosion products, or both, during this test may indicate that the oil will form insolubles or corrode metals, or both, during field service. However, no correlation with field service has been established.
