The hydraulic system of a rotary drilling rig is very important, as the performance of the hydraulic system directly affects the operational performance of the rotary drilling rig. From our observations, seventy percent of hydraulic system failures are caused by hydraulic oil contamination.

1. Hydraulic oil oxidation and deterioration: When the rotary drilling rig is working, the hydraulic system generates a large amount of heat due to various pressure losses, causing the temperature of the hydraulic oil to rise. When the system temperature is too high, the hydraulic oil is prone to oxidation. Oxidation can produce organic acids, which corrode metal components and generate insoluble gel-like precipitates, increasing the viscosity of the hydraulic oil and degrading its wear resistance.

2. Contamination by particles in hydraulic oil: Hydraulic systems and components can introduce contaminants into the system during processing, assembly, storage, and transportation; insolubles can form after air or water leaks during use; metal wear particles from wearing components; and the mixing of dust from the air, all can easily form particulate contaminants in hydraulic oil. The mixing of particulate contaminants in hydraulic oil can lead to abrasive wear, reducing the lubrication and cooling performance of the hydraulic oil.

3. Mixing of water and air in hydraulic oil: New hydraulic oil is hygroscopic and contains trace amounts of water; when the hydraulic system stops working, the temperature of the system decreases, and water vapor in the air condenses into water molecules mixed into the oil. The mixing of water in hydraulic oil will reduce the viscosity of the hydraulic oil, promote the oxidation and deterioration of the hydraulic oil, and form water bubbles, worsening the lubrication performance of the hydraulic oil and causing cavitation.