A guide to recognizing the causes of hose failure
When a pneumatic or hydraulic hose fails, the problem can be caused by issues such as incorrect selection of components, wrong assembly process, poor installation, or a combination of the above. This post explores some of the common failure and solutions to it. Note that if a problem can be recognized, you should target preventing it as opposed to dealing with the consequences.
Problem 1: The fitting used on the hose has blown off
Cause: The possible cause of this problem is that the hose was not fully inserted into the fitting shell during assembly. For your hose to hold firmly and work efficiently, it is important that it is secured by all the shell’s grips. The last grip in the shell is particularly important to the development of full holding strength.
Solution: The solution to this problem is hose assembly replacement. Before inserting the hose, ensure to make the cover correctly by following the recommendations in the catalog. Then, push the hose into the shell until it lines up with the mark.
You could also use an insertion-depth gauge to ensure the hose is inserted correctly.
Problem 2: The hose has become hard and brittle
In addition, the hose cover cracks at room temperatures. When you remove the hose, it is also rigid and stays in the same shape.
Cause: The main cause of the problem is that the hose was exposed to excessive heating. The high temperatures broke down of elastomers that give the hose its flexibility. Aeration of oils can cause oxidation on the inner side of the hose resulting in hardening. Then, the combination of heat and oxygen accelerates the hardening of the tube. The process of cativation could also cause a similar effect.
Solution: You need to review the entire application. Lower the temperature of the ambient air and fluid moving via the hose. You could also replace the hose with a different one that has a higher temperature rating.
If the problem is caused by ambient heat, it is advisable to install heat shields. If the problem resulted from high fluid temperature, it can be addressed by improving the system efficiency, lowering the fluid temperature, or installing a heat exchanger.
Problem 3: Leaking between the hose and shell of the fitting. In some cases, the hose might also have blown off
Cause: The fitting shell was either crimped too much or little when it was being assembled.
Solution: The solution to this problem is replacing the hose assembly. You need to get the right fitting and follow the correct instructions when crimping. Note that this should include the right tooling.
Problem 4: The hydraulic hose has burst and reinforcement wires also failed
This problem can be noticed in the braid along the outer part of the hose. In the failed area, there is little or no outward deflection.
Cause: The hose used on the system has seen its better days. This is perhaps because of high-pressure cycles or regular flexing in a specific area. The truth is that the hose has outlived its usefulness.
Solution: You simply need to review the system and change the assembly.
Problem 5: The hose is leaking through weepage or pinholes
The problem can also be evident via bubbles that appear on the hose cover especially near the fitting. In some cases, the hose might have burst near the fitting and started showing signs of corroded wires. However, it does not depict signs of obvious cover damage.
Cause: The main cause of the problem is damage to the inner section of the hose during the fitting assembly for lack of proper lubrication. Incorrect fitting assembly can also permit moisture to seep through the fitting socket resulting in reinforcement wires corrosion.
Solution: You need to rethink the assembly method and replace the hose assembly.
Problem six: External damage to the cover of the hydraulic system hose
The hose might also have burst in the section with a twist or features unbroken wires in the point of failure.
Cause: The main cause is twisting of the hose because of poor lubrication during assembly.
Solution: You need to review the hose assembly procedure. Then, replace and reroute the hose assembly adding clamps where possible. To be sure that the hose flexes well, consider using a layline.
Problem 7: Burst hose with torn cover and signs of wires deterioration. Some could appear corroded, broken, or rubbed
Cause: This problem is caused by excess chaffing of the hose on an external object such as brackets, sharp corners or wrong size cramp.
Solution: You need to replace the hose. Then, use a protective sleeve to prevent scarring. It is also important to re-route the hose assembly and ensure that only the right sized clamps are used.
To keep your hydraulic or pneumatic system running optimally, it is important to have a robust inspection and maintenance program. Remember that when you note any of the above problems, it is important to have the system checked and proper corrective measures implemented immediately.