What is in this article?:
- Engineering Hose Assemblies for Safe and Reliable Performance
- Avoiding failure
Selecting hose and connectors for safe, reliable operation.
Selecting and applying the wrong assembly can be dangerous and even fatal. Personal injuries from hydraulic hose can include high-pressure fluid injection, burns from hot hydraulic fluid, fire and explosions from fluids, and broken bones from a whipping assembly. Hose systems properly selected and used within manufacturer’s guidelines will operate safely and can last for many years.
Improper application is the most common cause of hose failure. Always compare specifications with the application requirements. Pay particular attention to:
• Maximum operating pressure of the hose.
• The hose’s recommended temperature range.
• Is the hose rated for vacuum service?
• Fluid compatibility of the hose.
If these areas don’t match the application requirements, select another hose. And if in doubt, don’t hesitate to call on the manufacturer’s expertise.
Improper assembly and installation is the second major cause of premature hose failure. This can involve anything from using the wrong fitting to poor routing of the assembly. Manufacturers provide training material to help prevent these problems.
External damage can range from abrasion and corrosion to hose crushed by a lift truck. These problems can normally be solved simply once the cause is identified. The hose can be rerouted or clamped, Circle 202 or a fire sleeve or abrasion guard added. In the case of corrosion, the answer may be a more chemical-resistant cover or rerouting the hose to avoid corrosive materials.
Frequent or premature hose failure can be a symptom of equipment malfunction. Always consider this factor, because prompt corrective action can sometimes avoid serious and costly equipment breakdown.
Occasionally, the failure lies with the hose itself. The most likely cause of a faulty rubber hose is old age. Check the hose’s layline to determine the date of manufacture. (For instance, 2Q04 means second quarter of 2004.) The hose may have exceeded its recommended shelf life.
Other factors which reduce assembly life include:
• Flexing the hose to less than the specified minimum bend radius.
• Twisting, pulling, kinking, crushing, or abrading the hose.
• Operating above maximum and below minimum rated temperatures.
• Exposing the hose to surge pressures above the maximum working pressure.
• Mixing hose, connectors, or assembly equipment not recommended by the manufacturer, or not following manufacturer’s instructions for fabricating assemblies.
A recommended practice is to perform ongoing visual inspections of equipment and hydraulic components. Hose and fittings should be checked for:
• Leaks at the fittings, ports, and in the hose.
• Exposed, damaged, abraded, or corroded reinforcements.
• Cracked, damaged, or badly corroded fittings.
• Bulges or blisters in the hose.
• Damaged or missing clamps, guards, or shields.
• Any other signs of significant deterioration.
Consider replacing the assembly if technicians spot any of these conditions. Like any component on a piece of equipment, maintain and inspect hoses at regular intervals and replace when necessary.
Greg Brown is Distributor Training & Support Manager at Ryco Hydraulics Houston. for more information, viist ryco.com.au.