Failure Mode Analysis of Hydraulic Hose Assembly (II)

The hydraulic pipe assembly is an unrepairable product. There are 14 failure modes. There are 8 failure modes.

Example 7- Minimum bending radius of hoses

Symptoms: The bend of hydraulic pipe is broken. Hose usually remains flexible.

Reason: The minimum bending radius of the hose is not considered.

Solutions: Replace hose assembly. Increase hose length according to minimum bending radius requirement and repipe. Fix hoses with pipe clamps if necessary.

Example 8- Hose fluid mismatch

Symptoms: Severe damage to the inner layer, swelling or layering, or even peeling.

Reason: The fluid does not match the material of the inner rubber layer.

Solutions: Replace appropriate hydraulic pipes or fluids according to material matching sheet.

Example 9 – Sparkling

Symptoms: The out layer of hydraulic pipe is bubbling. The inner layer or outer layer foams or becomes soft.

Reason: Fluid is incompatible with hose material. Blistering occurs when a fluid or grease reacts in the hose.

Solutions: Replace hose assembly. Change hydraulic pipe type or fluid medium depending on chemical compatibility.

Example 10 – Aging

Symptoms: Fine cracks appear in the inner layer but remain elastic. But there is no obvious crack in the joint.

Reason: The air inside the hydraulic pipe is too dry, which causes the aging of the adhesive layer.

Measure: Replace hose assembly resistant to dry air.

Example 11- Excessive temperature

Symptoms: Hydraulic pipes are harden, become brittle and crack at ambient temperature. The outer coating shows signs of drying and zooming.

Reason: Ambient temperature exceeds hose temperature limit and gradually loses elasticity. Or the internal hose into carbon dioxide and oxidation reaction can also cause the hardening of the hose.

Measures: Refer to hose application manual, replace hose resistant to high temperature or install heat resistant protective sleeve.

Example 12- The temperature is too low

Symptoms: At operating temperature, the inner or outer adhesive layer cracks but remains soft and pliable.

Reason: The ambient temperature is lower than the minimum service temperature of the hydraulic pipe.

Solutions: refer to hose application manual to increase ambient temperature or replace hose resistant to low temperature.

Example 13- High Pressure

Symptoms: Hydraulic pipe burst, reducing service life. Usually, the burst occurs suddenly, and the steel wire and rubber coating show no signs of wear.

Reason: The actual working pressure exceeds the rated working pressure of the hose.

Solutions: Adjust the working pressure of the system or replace hoses with higher pressure classes.

Example 14- Excessive flow rate

Symptoms: Hydraulic pipe leak. The inner wall showed signs of being chipped.

Reason: Perforation of the inner wall due to wear due to excessive flow rate. It is also possible that the fluid medium contains small particles and make the inner wall wear.

Solutions: Replace hoses of matching size according to flow rate and medium.