Will hydraulics ever get past the leakage issue? I’ve heard people discuss this question countless times over the three decades that I’ve worked in and written about the technology. Time and time again, people bash this useful technology because of perceived problems with leakage. I have encountered this negative talk on factory floors, in educational institutions, in online forums, and elsewhere. But shouldn’t the conversation have evolved by now? Components today are better than ever, system design has made great strides, and fluid power education is available around every corner. So, why does the whispering about leakage persist?
The editors of Fluid Power World decided to tackle this question head on, examining the industry’s vexing scarlet letter and asking what can be done, both from a technology and a marketing standpoint. We asked users, readers, manufacturers, and industry experts for their thoughts. In all, almost 50 people responded to our survey questions or were interviewed by our staff members about the topic. Here’s what we discovered.
Is the problem real?
Concerning external leakage, some of our respondents did see positive steps forward for the industry. Billy Goodman, a Mechanic for DOD, believes today’s hydraulic systems are built more with leakage prevention in mind than older systems were.
“Better sealing materials and better hose materials have taken care of a lot of the leakage issues. Stopping leaks before they start is stressed more today,” he said.
And Burk Schmidt, Fluid Power Consultant for Creative Hydraulic Solutions, explained that while external leakage could be a problem for some installations, it surely does not have to be a problem today.
“We have good components and fittings at our disposal,” he said. “Therefore, with the use of good components and fittings — as well as proper system design, this really does not have to be a problem. By good fittings, I mean quality fittings with an elastomeric seal. When properly tightened, they do not leak. Have you ever seen hydraulic oil dripping from a commercial airplane? They use hydraulics for flap control as well as the landing gear extension and retraction. By good system design, I mean correct hose routing, use of the right valves, and control sequences to avoid shocks in hydraulic pressure.”
Brian Krieger, North American VP of Sales & Global Marketing Manager for Engineered Inserts & Systems Inc., said that their entire business is to avoid leakages with respect to cross drilled ports.
“When a customer comes to EIS to solve an issue of leakage, we have many products that can 100% leak free permanently seal. But our goal is more than just to stop the leak. It is to offer our customers the most cost competitive overall sealing solution.”
But a vast majority of respondents said that leakage is still a major issue.
“Many manufacturing facilities spend significant economic resources on mitigation products (kitty litter). I have seen some shops with pallets full. All this material must be considered HazMat when used for its purpose. Walking around a lot of facilities, you can see mounds of it collected around leak points or under machines. Most never gets disposed of until the machine is dismantled,” said Robert Scaggs, Instructor at Lone Star College.
And Ron Claus, Director of Engineering, System Seals Inc., expressed similar concerns.
“Leakage in hydraulic systems today is a very big problem that affects many varying aspects of the industry,” he said. “Whether it’s a ball valve leaking in the oil & gas market, or leakage from a hydraulic cylinder on a backhoe, the higher-level concerns are environmental impact, safety concerns, immediate and long-term expense, and a high probability of reduced performance.”
For Casey Ruttan, a Territory Manager for Power Systems Inc. of Florida, leakage is still a major problem in his experience, and proper training may be at the core.
“Daily, I see systems with drips, wet hoses, oil coated valve stacks, and seeping fittings and cylinders. Lack of knowledge, training, awareness, and attention is really the root problem. Many of the folks I meet in maintenance capacities have had little to no training in fluid power concepts, let alone maintenance or safety practices,” said Ruttan.
“I had a customer just last month tell me how he never changes O-rings anymore because they still leak. When I asked him if he had a 900 series O-ring kit, his response was, ‘No what’s that?’ I’d seen this before, so I make sure to ask in a way that doesn’t embarrass anyone. Expecting someone to know this is just not reasonable. Usually that opens the discussion to training. There really isn’t enough training on basic fluid power.”
And leakage is serious business, as Matt Zalick, Director of Business Development at System Seals Inc. noted. “I believe leakage is the number one issue in hydraulic systems across all equipment types. If a leak exists, the problems are many: lost power, environmental hazards, unsafe working areas, increased fire risk, lost product, unplanned downtime to repair, and cost of leaked oil/grease. Just one or two of these issues can greatly affect the bottom line.”
Rob Klohs, Ops Manager and Senior Fluid Power Engineer at Fluid Power N.T., stressed that it really does depend upon the industry.
“I have been lucky enough to work in 18 different industries in several countries. One client lost more than $5 million a year in fluid loss. Some mining clients lose thousands of gallons per year. At one time, the loss of fluid through leakage in the European mobile market amounted to $25 million per year. The impact on the environment is unknown and can only be speculated. On the one hand, the loss itself presents an increase in the cost of goods and services as the cost of lost fluid will be passed on to the consumer. Although oil itself is an abundant resource (not dwindling as you have been made to believe), the impact on the planet through continued manufacture is problematic for a number of reasons.”
Several industry colleagues mentioned the leakage problems associated with NPT fittings. One was Mark Paxton, CEO of HANSA-Flex USA.
“External leakage is a tremendous problem for fluid power and probably one of the primary reasons why alternative power transmission strategies are coming forward. The industry is always on the defensive, especially in power transmission applications where electro-mechanical actuators can be effectively applied — for example, turf care. The resolution, while seemingly simple in my eyes, has decades of momentum that prevents companies to make an about-face with their fluid conveyance and port to port connection schemes away from NPT and JIC,” said Paxton.
And while not shying away from the issue, Carl Dyke, President, CD Industrial Group Inc. (and a longtime contributor to Fluid Power World) tried to stay positive.
“Hydraulic system leakage is a very large problem,” said Dyke. “The good news is that this problem is being solved fairly quickly now. Witnessed on newer systems, the problem is primarily a lack of sound installation and maintenance practices — where on older systems, the problem is often the fit and style of hydraulic connections.”
Getting to components
When asked what components were most responsible for leakage, users mentioned a couple of them over and over: hose and fittings. Cylinder and their seals, directional valves, O-rings, pump shaft seals, and flanges were also called out.
“In correctly assembled and maintained systems, the connections between hose and end fittings are the most subject to leakage failures. For systems not assembled correctly, it would be every threaded connection, regardless of the type,” said William Ketel, an Engineer with Number 28 Engineering.
Michael Terzo, Founder and CEO of Xirro, LLC, agrees. “I would say the number one issue responsible for the vast majority of leaks is incorrect fitting use. Many lower-cost, custom, or assembled systems still use JIC fittings. These fittings are prone to incorrect tightening, vibration failure, scratches on the flare face, and other issues. They are used so extensively because they are lower cost than, say, a flat-face O-ring fitting … the industry has basically decided that the value of lower priced machines outweigh the issues of leakage in many applications.”
Similarly, Will Morris and Joseph Smiley, RS Category Manager and Nachi Distribution Sales Manager (respectively), for RS and Nachi Hydraulics, said that connections are where leakage problems are most likely to happen.
“Major contributing factors to leakage in a hydraulic system are its connections. Every pipe, tube, and hose connection becomes a potential leak point for external leakage … Leakage from hoses is also common if connections are not maintained or if pressures exceed the rating of the hose. Hydraulic hoses can also burst due to unnecessary abrasion or degradation over time, due to lack of maintenance. Again, correctly installing and maintaining these items can prevent many problems. The issues are more often caused by not addressing these issues, rather than the components themselves,” Morris and Smiley said.
“I think hoses and seals are the most common components responsible for leaks,” said Marc Schonhoff, Account Manager, Idemitsu Lubricants America. “These can fail for a number of reasons, and although they are not typically very expensive to repair, the potential for lost revenue leads to a delayed response.”
For Gene Mitocky, President, Emmco Inc., most of the issues are related to the plumbing of the hydraulic systems; he noted that pipe threads are still being used and these are prone to leaking.
“Welded pipes that have leaks at the welded connections [can result from] fatigue cracks or improper fabrication to begin with,” he explained.
Other areas that Mitocky noted to be wary of for leakage are hoses that are rubbing, exposed to heat or environmental conditions, or have been in service beyond their useful life; piping/tubing that is not properly clamped; and seals that are exposed to higher operating temperatures.
“Shock in the system plays a big role in piping and component failure,” Mitocky said. “Components definitely contribute to the leakage issue, hydraulic cylinders being one of the common sources because of the rod seal failure. The other components, valves, and pumps usually leak because of seal failures, typically due to heat, or because they are used in a dynamic application and wear out.”
Issues with seals were mentioned by many respondents. Michael Cook, Global Segment Director Off-Highway, Trelleborg Sealing Solutions, explained that seals are going to be one of the most associated components with leakage, as they are often times the last line of defense between the enclosed hydraulic system and the external environment.
“Old style sealing technologies at the threaded connection are the #1 culprit in my experience,” said Dan Detweiler, Value Added Systems and Technical Services Manager – U.S., Parker Hannifin Corp. He explained that metal-to-metal connections, combined with application challenges, such as vibration, are high on the list of failure modes.
“During our onsite evaluations of fluid conveyance systems, a common issue is the number of connections used in order to get the job done,” Detweiler said. “In some instances, three or more stacked adapters are used to get from one connection to another. Our goal is always to reduce the number of threaded connections in every system, which eliminates or reduces the number of leak points. Another key area is the quality of the installation process at the assembler level. For example, more torque is typically not the answer, but it is the most common ‘fix’ for a fluid power leak.”
Improvements over time
Claus explained that there have been advancements in many areas to control leakage. For example, on the polymer science side, improvements have been made to elastomers and thermoplastics to make them more robust. These are material formulations available to us now that simply weren’t a decade ago.
“Improved sealing materials/designs, better maintenance/installation practices, and more efficient design of components” are some of the improvements that Michael Cook, Global Segment Director Off-Highway, Trelleborg Sealing Solutions mentioned.
“In addition to the polymer science, there have been advancements in technical resources to better understand failure modes, offering solutions to legacy problems. Higher level manufacturing processes are producing more reliable components all while improving their quality control mechanisms and statistical capabilities,” Claus said.
Dyke was among the many who also highlighted the increased use of elastomer seals in fitting technology, along with manifold technology.
“The CAD/CAM machined manifold, where handfuls of screw-in or slip-in cartridge valves can be integrated — along with other valve assemblies directly attached and sealed to the manifold surface — has removed many hoses, and more importantly, countless fittings and external connection points. This is huge step in the right direction in order to minimize leakage,” Dyke said.
Another longtime contributor to Fluid Power World, Josh Cosford, VP of Sales & Marketing, Higginson Equipment Inc., said that he thinks the biggest improvements have come from precision engineering and machining.
“We’re now able to hold near-microscopic tolerances so that perfectly mated pistons, bearings, wear plates and other items fit so precisely without interference that little room for excess oil to leak remains,” Cosford said.
But Klohs took a sour note on the state of things.
“There has been no improvement — if anything it is worse, not better,” he said. “CAD/CAM manufacturing has made things less robust due to less material being used in many components. [There are] smaller systems running at higher pressures in extreme conditions and a lack of real world understanding of component operational envelopes by many design engineers. No real understanding by mechanical engineers with no fluid power or very little fluid power knowledge.”
User failure is key
Bill Hartwick, Technical Director, Filter Specialties Inc., said that after 40 years of seeing different scenarios, he feels that 90% of leakage is due to user error (improper maintenance or operation) versus 10% where components are underperforming.
“Any component that fails in a short period would typically be replaced with better quality parts to correctly fix the issue,” he said.
Morris and Smiley weighed in here, explaining that user error occurs when the level of workmanship is not at a high enough level and the system plumbing is cobbled together — and not well thought out.
“Fittings are sensitive to torque considerations for tightness. Misapplied components will present excess pressures on the performance of components and systems, which exacerbates wear and leakage concerns. No product is 100% failure proof, but as in most things, there are various levels of quality; often times, lowest cost products can suffer from a lack of quality. In general, it is probably more common for leaks to be caused by incorrect installation, exceeding ratings, and lack of maintenance,” they said.
“70% of what we see is user error, improper installation of a hose or tubing, or improper connection or improper seeding of the fitting (size is incorrect),” added Fred Mercuri, VP of Sales – Western Region, Brennan Industries.
One industry veteran who works for a major manufacturer said that they think leakage has more to do with laziness and/or a money saving maintenance strategy of ‘don’t fix it until it’s broken.’ Then someone decides to put a band-aid on it or buy the wrong replacement parts because the new or right ones have a long lead time — or are too expensive.
“Oftentimes, we don’t receive enough of the operating requirements because they are not known,” he said. “Buying the lowest cost could result in a component under-performing or prematurely failing, depending on the application.”
Schonhoff thinks components underperform due to lack of knowledge or user error. He explained that if the proper materials are selected and components are used correctly, many issues could be avoided. “Proper education and training can be costly and time consuming, but the benefits are typically much greater,” he said.
“Lack of technical knowledge is an overwhelming factor,” said Rory McLaren, Instructor, Fluid Power Training Institute. “However, cheap design is a close second. The fluid power industry seems to be satisfied with the status quo. It earned the reputation of being inherently dirty‚ and seems to be satisfied with its image.”
Perception issues
Zalick believes that hydraulics is seen as a “dirty” technology by many people outside our industry.
“Increasing education on things like seals and hoses can go a long way in understanding why quality parts are important,” he said. “Once we can stand by the safety and show you can cleanly operate hydraulic equipment, people will start to drop the misconceptions on our industry.”
Jeff Zimmerer, Manager/Designer, Automated Hydraulics, feels that the typical industrial worker sees hydraulics as a last resort, because they do not want to deal with the potential leak issue. “Most people do not recognize that of all of the technologies available to us, hydraulics has the highest power density (power/volume) of any technology,” he said.
Detweiler said the perception that all hydraulics will leak is a significant drag on fluid power.
“The industry needs to respond in two ways: improving the education and best practices knowledge base of fluid power users on fluid conveyance systems and in some instances using localized fluid power solutions where the actuator and hydraulic power unit are combined into a single component,” he said. “Localized power eliminates the need for a centralized HPU and long fluid conveyance lines. Depending upon the market and application, one or the other solution may be best.”
Dyke stressed that the perception of leakage continues to be extremely damaging to the hydraulics industry. He said that those who purchase and operate hydraulic systems in any form need to reject the notion of ‘acceptable leakage’ — and hold the machine designer and manufacturer to account for a high integrity design. But that said, users should then be prepared to pay for this high quality. Those same hydraulic system users need to adopt a maintenance mindset and goal of zero-leakage and work towards it.
“Unfortunately, I think the perception of leakage is prevalent in the marketplace and falls under an easy target. You could have 1,000 cylinders that are leak-free, but [there’s] one troublemaker and the perception runs wild,” said Claus. “To solve the problem, approach the leakage issues with proven problem-solving solutions. Understand the leakage issue, or failure mode, by using FE analysis, conduct technical calculations, have in-depth applications and material knowledge to offer innovative sealing products that not only solve the leakage issues, but promote long life and high performance.”
Extra: Internal leakage woes
External leakage issues get most of the attention, because you can easily spot the evidence in or around the hydraulic system. But internal leakage robs systems of efficiency and can have long-term consequences.
Pavankumar, a Senior Engineer / Product Engineering, at Ajax Engineering Pvt Ltd., noted that in any hydraulic system, internal leakages plays a major role directly on performance.
“Internal leakages directly depend on the components used in the hydraulic system, which is directly dependent on the tolerances given in components assembled in the working system,” he said. “Internal leakages are harmful for the system but not fatal … [they] can be reduced by improving design and material quality in the component manufacturing by analyzing application temperature, working media, and duty cycle.”
Filed Under: Couplings & Fittings, Fittings, Couplings & Adapters, Fluid Power World Magazine Articles, Hose & Tubing, Sealing, Valves & Manifolds
