You can help reduce the damage to exposed hose assemblies by selecting a vendor that carries hoses with abrasion-resistant covers or sleeves.
Many companies that operate equipment or large fleets of trucks have a preventative maintenance schedule in place to reduce downtime and lost revenue. Within these schedules are such familiar items as oil and fluid changes, filter replacements, and tire-and-brake inspections. But very few companies have a planned schedule to include their high-pressure and hydraulic hoses.
It can be challenging to implement hose inspections into a preventative maintenance schedule. People are often unaware of how long a hydraulic hose should last, its source traceability, what to actually look for, and where to find reference materials.
Let's take these items one at a time, starting with the question, “How long can I expect this hose assembly to last?” Common answers usually include a timeline of five or even 10 years – less if the equipment works in a demanding environment. In reality, the lifespan of a hydraulic hose assembly is measured, not in months or years, but by the number of impulse cycles it experiences.
An important part of this process is to install hose assemblies designed and tested to work together. This means the hose manufacturer and the fittings manufacturer have fully tested their products to ensure compatibility. This does not necessarily mean the manufacturer of both the hose and the fittings need be the same; it means the full range of compatibility testing was carried out.
Before hoses go into production, manufacturers need to carry out impulse cycle tests to meet internationally recognized standards. These standards require the hose assemblies to withstand impulses often exceeding their maximum working pressure. Depending on the type of hose and reinforcement, tests often involve subjecting the hose assembly to hundreds of thousands of impulse cycles.
Once a hose assembly on a piece of equipment has experienced the maximum number of impulse cycles in the original manufacturer's tests – for example 200,000 cycles – it does not mean the assembly will fail on the 200,001st cycle. It does mean the assembly's overall performance will then start to deteriorate. From this point, the rate of deterioration will depend on how well the equipment or machinery is maintained.
Once you better understand how long the hose assembly should last, the next step is to find out when it was installed. In some cases, it may be one of the original hoses fitted when the machine was manufactured. On the other hand, it may have been replaced several times, especially if it has been exposed or in an area where it could sustain damage. This is where source identification becomes important. When selecting a vendor for your hydraulic hoses, try to locate one that offers hose tagging and cleaning for each custom-built hose assembly supplied.
Hose tagging and identification can be a first step toward adding hose surveys or inspections to your maintenance schedules. The next step is learning some of the visible indicators often associated with hose failures. These include:
• Hardening and cracking of the outer cover, exposure and oxidation of wire reinforcement. Extreme cases include missing sections of the outer cover, and a wire reinforcement that is starting to unravel.
• Bubbles on the outer cover, indicating the inner liner may already be compromised, or that there is an incompatibility between the medium and the hose liner.
• Any rust or dampness where the connection meets the hose.
• Bent or crushed fittings and hoses kinked by site damage, causing flow restrictions.
• Signs of the hoses rubbing together, creating wear points.
• Missing brackets and clamps that increase the possibility of damage.
It's helpful to create a basic checklist that matches the above items with some photographs of examples.
Equipment and machinery on construction sites are exposed to site damage in a number of different ways. You can help reduce the damage to exposed hose assemblies by selecting a vendor that carries hoses with abrasion-resistant covers or sleeves.
There are three common types of hose sleeves readily available: coiled steel, plastic spiral wrap or textile sleeve. Depending on the application and environment, any of these three types is usable on construction-related equipment.
Another factor leading to premature hose failure is contamination of the hydraulic system itself. Small particles created by wear, or by the breakdown of pumps or valves, can damage the inner liner of the hose. Besides the regular oil and filter changes, some companies are adding oil sampling with particle counts to assist with maintenance scheduling.
It's important to recognize potential problems and their solutions. But onsite safety and best practices for heavy equipment must remain paramount. Safety should always be part of your daily routine and your first consideration when working onsite.
Here are some common onsite safety tips:
• Notify your superior and point of contact when you arrive on site.
• Observe any site-specific safety rules and conditions.
• Assess risks, including trip-and-fall hazards.
• Wear appropriate personal protective equipment.
• Park in a safe area, turn on any necessary lights or strobes, and place any warning triangle or cones.
• Check the equipment you are working on to make sure it's on stable ground.
• Ensure buckets, arms and lifting equipment are at their lowest point of rest. Make sure they're stable, and that lift-arm locks are in place with wheels chocked.
Some of the best practices to observe when working on hydraulic systems include:
• Do not work on any piece of equipment unless you are properly trained.
• Follow the manufacturer's guidelines and recommendations.
• Make sure power sources and stored energy devices are isolated, and that everyone follows lock-out/tag-out procedures.
• Relieve pressure safely from all parts of the hydraulic system, especially those with accumulators.
• When working on a component, make sure nothing can create a hazard by falling or descending.
• Keep environmental spill products available in case of an oil or lubricant spill.
• Use only components that meet or exceed the application's requirements.
These safety tips and best practices do not cover every situation, but they are helpful reminders of dangers we are all exposed to when working or attending a job site.
About the author
Jamie Vokes is the Training and Field Support Manager at Pirtek USA, with more than 25 years' experience working with hydraulic components and systems in multiple industry sectors, both nationally and internationally.