How to Extend the Service Life of Industrial Hydraulic Components

The majority of hydraulic failures are not sudden breakdowns. They progress over time due to contaminated fluid, thermal cycling, and weeping, bypassing leaks. Other ‘no brainer’ practices that will extend hydraulic system life may not seem so obvious. But in hindsight, it stands to reason that a system designed, built, and installed with contamination control measures, and equipped with ‘no brainer’ features, will also last longer.

Fluid contamination is the primary threat

Most hydraulic system failures are caused by fluid contamination, and this percentage remains the same regardless of whether the equipment is old or new. New equipment typically has higher operating pressure and is more sensitive to contamination. The smaller clearances in modern high-pressure vane and piston pumps, for example, are ground to one-third the width of a human hair.

The best way to keep contaminants from reaching those tight clearances is still using filters. The ISO codes, which also apply even if you’re in the desert or another harsh environment, should tell you what the best available filter efficiency is. However, you’ll also want to take into consideration all the other variables – environment, age of equipment, pumping speed – when determining which filter to use. This is something a filter supplier should help with, if you don’t yet have access to oil analysis in all your plants.

Other types of contamination – water and air – also quickly degrade hydraulic fluid. Outstanding water removal occurs at a rate of 12 ounces of water per gallon compared to two to four ounces; there’s a non-negligible difference there. The standard for parts per million of air entrained in fluid also has room for improvement. Most from-the-barrel hydraulic fluid will contain around 10 percent air, which is three percent too much for high-pressure systems. What people don’t realize is that fluid in general is unclean – new fluid, though filtered. New oil in barrels regularly starts out at extremely low cleanliness codes.

Temperature management shapes component lifespan

Cooling power requirements will increase in line with the size of the pump and how efficiently its frictional losses are converted into heat – so a well-designed circuit that minimizes elbows and piping can make a significant difference, particularly when a power unit is close to its mechanical limits.

A cooling package designed for a hydraulic installation should be specced to operate within a given temperature difference, rather than just cooling to a given fluid temperature. It should filter properly, which is to say that it should offer the correct filter size and type for the installation.

Parallel coolers are another solution worth looking at, especially since the cost of a parallel cooler layout is often significantly less than that of a series cooler (or coolers). Careful installation of a parallel cooler can also effectively reduce the space it requires compared to the larger series cooler.

Small leaks signal bigger problems

A seal with a minor leak can seem trivial. After all, it’s likely identified by inspection or caught in a drip pan. It’s easy to rationalize postponing the repair until the next scheduled downtime but doing so could be a costly mistake.

External leaks allow in external contaminants which can cause damage to systems. If that fluid is operating at pressure, there are likely to also be invisible leaks. The same path that fluid under pressure can use to escape allows air and moisture to enter. Air entrained in hydraulic fluid causes aeration in the hydraulic fluid, leading to cavitation as the entrained air cools and collapses in high-pressure areas of the hydraulic and causes pitting on metal surfaces. Cavitation erosion on hydraulic pumps and valves has been directly linked to air leaks at hydraulic connections.

Recognizing wear before it becomes failure

Scheduling regular checkups is the first step. What helps to avoid those checkups from becoming a whole series of unnecessary visits should be the ability to recognize the signs of disease early on.

Normal maintenance will tell you when the rubber gaskets on a hydraulic-cylinder cap or a check-valve pressure port have lost their original flexibility and started to fail. Standard checks advise when a fixed-volume pump is no longer developing enough pressure to suit system needs, or when an actuator is starting to drift. This is usual wear and tear.

But know that those relaxed tolerances on a pump could also be early warning signs of a severe fluid leak. Small drifting movements on the hydraulic rams may be enough to indicate a change in packing pressure might save the seal. Insufficient pressure in the hydraulic circuit might be the cause. Uneconomically increased power rates on the electric engine driving the hydraulic pump can have the same root.

A small seepage in the suction line or a stuck-open pressure-relief valve might go unobserved in the era of normal tank weepage within 10 minutes of pump shutdown. The same applies to wimpy-sounding pump noises in a factory filled with generators. When a system shows several of these signs together, operators working with Heavy Hydraulics can identify internal wear patterns that aren’t visible through routine inspection, and determine whether reconditioning or targeted replacement is the more cost-effective path.

Training changes what gets caught early

The effectiveness of maintenance programs depends on the people implementing them. Technicians who are aware of the sounds produced by cavitation, or who know how to inspect the micron ratings on new filters in addition to part numbers, are more likely to detect issues at an early stage. Filter efficiency makes a difference – in a high-pressure system, a 10-micron filter and a 3-micron filter cannot be used interchangeably, even if they come from the same series.

Systems that provide regular training for operators report lower instances of unscheduled downtimes compared to systems that rely solely on set service schedules. The service schedule sets the plan and regular training fills in the rest.

The life of a hydraulic system is more dependent on the conditions it is exposed to (cleanliness of the fluid, temperature, and leak tightness) than on the heavy duty of the components at the time of purchase. If you get the conditions right, the equipment will follow.