How to maintain the hydraulic system of an HDD drilling rig?

I. Hydraulic Oil Management
1. Regular Oil Replacement
Hydraulic oil should be replaced annually (or every 2000 hours). ISO VG 46 anti-wear hydraulic oil is preferred. Thoroughly clean the oil tank and replace the filter element during oil changes.
2. Oil Cleanliness Control
Oil must be passed through a 10μm filter, and oil contamination must be controlled below NAS level 8.
II. Key Component Maintenance
1. Hydraulic Pump and Valve Assembly
Check the pump body temperature monthly (normally ≤60°C). Abnormal heating should be checked for oil insufficiency or contamination.
Clean the control valve quarterly to remove impurities from the valve core (kerosene can be used for flushing).
2. Cylinder and Seals
Inspect the piston rod seal. Replace if leaking >5 drops/minute.
Tighten the cylinder piston nut every 500 hours to prevent loosening and pressure drop. 3. Pipeline and System Inspection
1. Pipeline Installation Specifications
The oil suction pipe must be sealed and leak-proof, and the oil return pipe must be inserted below the oil level to prevent air bubbles from entering.
2. Pressure Test
After replacing a hydraulic valve, perform a 15 MPa pressure test for 5 minutes to ensure no leakage.
4. Daily Operation Precautions
1. Avoid Overloading
Excessive pressure operation is strictly prohibited (for example, the relief valve setting should not be increased at will).
2. Regular Inspections
Check the oil tank level, pipe joints for leaks, and filter blockage daily.