Four kinds of hydraulic hose failure analysis

The use of high-pressure hose will be of great help to us, but it will also produce some problems. Let's first talk about the failure analysis of the high-pressure hose assembly.

1. Symptoms: The hose is cracked inside and outside, but the elastic material is still soft and elastic at room temperature.

Cause: The possible cause is that the ambient temperature when the hose is bent is very low. Most specification hoses are rated at -40 degrees, some AQP hoses at -49 degrees, military hoses at -54 degrees, some thermoplastic hoses at -54 degrees, and Teflon hoses at -73 degrees.

2. Symptoms: The inner tube of the hose is very hard and cracked.

Reason: High temperature is easy to precipitate the plasticizer of the inner tube, which is a kind of material that can make the hose soft and plastic. The entrainment oil oxidizes the inner tube. This oxidation reaction on rubber products causes them to harden. Oxygen and high temperature will greatly accelerate the hardening of the tube inside the hose. Cavitation in the inner tube has the same effect.

3. Symptoms: The hose is broken, but there are no multiple wire breaks in the total length of the hose. The hose could break in more than one place.

Reason: This indicates that the pressure has exceeded the minimum burst strength of the hose. It is recommended to use a higher strength hose, otherwise the hydraulic line will show problems, resulting in abnormal high pressure conditions.

4. Symptom: The hose is broken, peel off the outer layer of glue to check the wire reinforcement layer. Irregular wire breaks were found along the entire length of the hose.

Reason: This indicates that the hose pressure wavers very frequently. SAE's impact test on a double-layer wire braided hose required 200,000 cycles to be stopped at 133% of the recommended working pressure. SAE's impact test for a four-layer wound hose required 500,000 cycles. If the number of system extrapolation pulses exceeds 1 million in a short period of time, it is best to choose the winding reinforced layer hose.