A hydraulic tube fitting may start leaking after installation even when there is no obvious problem with the fitting itself. Based on common issues we see during production and assembly, the cause is usually related to the tube, installation, or sealing parts.
1. Incorrect Tube Preparation
The tube should be cut square and properly deburred before assembly. A rough or uneven tube end can affect the position of the cutting ring and result in leakage.
For DIN 2353 fittings, correct tube preparation is especially important.
2. Incorrect Tube Size
The fitting must match the tube outside diameter and wall thickness.
Metric and inch tubes should not be substituted simply because the sizes are close. For example, 12 mm and 1/2" tubes have different outside diameters, which can affect the connection.
3. Incorrect Assembly or Tightening
The cutting ring or O-ring must be installed in the correct position. Over-tightening can damage the tube, fitting or sealing parts, while insufficient tightening may not provide proper sealing.
Different fitting systems, such as DIN 2353, JIC and ORFS, also have different assembly procedures.
4. Damaged or Dirty Sealing Parts
Check the tube, threads, sealing surfaces and O-rings before assembly. Dirt, metal particles, scratches or a damaged O-ring can cause leakage after the system is pressurized.
5. Tube Stress and Vibration
Tube misalignment, excessive bending or vibration can put additional load on the fitting. Proper tube routing and support can help prevent this type of leakage.
