Hydroelectric turbine systems operate in extremely harsh conditions. The corrosive conditions in challenging industrial and outdoor environments, especially in hydro market applications, greatly shorten the life of operational parts, such as cylinders and actuators.
Advanced cylinder coating resists corrosion
Parker Hannifin Corporation has developed an advanced cylinder-rod coating called Global ShieldTM that resists corrosion up to eight times longer than conventional coatings. Global Shield outperforms standard coatings like hard chrome, nitride, electroless nickel and hard chrome over electroless nickel when tested against the corrosive properties of salt spray, calcium chloride spray, and magnesium chloride spray.
Global Shield technology
Global Shield was developed in direct response to customer demands for an environmentally-responsible, corrosion-resistant coating that significantly reduces downtime associated with cylinder repairs and seal replacements. The Global Shield coating has a sub-micron structure that eliminates surface micro-cracks and delamination, especially when flexure occurs.
Extensive lab and field testing have validated the coating’s performance against corrosion and dynamic wear. Cylinders protected with Global Shield have demonstrated resistance to corrosion up to eight times longer than conventional coatings. Tests also confirm leak-free performance even after 1 million cycles and 2,000 hours of salt spray. When compared to hard chrome and tested using the Rockwell “C” Indentation Test, protocol, Global Shield exhibited exceptional interfacial adhesion and impact resistance, with almost no micro-cracking, chipping, spalling or delamination.
Compared to traditional rod coatings, Global Shield provides the following advantages:
- Significantly improves corrosion resistance—a result of the single-layer, fully-dense, submicron structure and the lack of micro-cracks
- Lower friction
- Ductile and tough—when the rod bends, so does the coating
- Engineered hardness (HRC 54 minimum) for wear-resistance
As a result, fewer cylinder repairs and seal replacements (and therefore less downtime) provide a longer life in corrosive environments. This results in lower service costs because the piston rod does not have to be replaced as a result of corrosion.
Another benefit of Global Shield is that it’s good for the environment. No chromium is required in the coating or the manufacturing process, which eliminates hexavalence, hazardous waste stream risks, and PEL (personal exposure limits) concerns and complies with RoHS Directive 2011/65/EU regarding recyclable coating materials.
Global Shield can be easily applied during original Parker cylinder manufacture or installed during aftermarket cylinder maintenance via a process that is both efficient and environmentally responsible. Global Shield is an available option for nearly all Parker cylinder sizes.
The ability of Global Shield rod coating technology to resist corrosion from salt spray, calcium chloride spray, magnesium chloride spray and other environmental conditions makes it ideal for challenging industrial applications. It is well-suited for hydro-oriented applications such as hydroelectric and marine/intermodal operations. Other industrial applications include mining, construction, material handling, renewable energy, and power generation, refuse, oil and gas, military, heavy-duty trucking, forestry and other challenging industrial and mobile environments.
Compared to chrome, chrome over nickel or other multi-layer/multi-process rod-plating technologies, Global Shield will improve cylinder performance with better initial and long-term ownership costs. It may also be an economic alternative to corrosion resistant steels when applied to carbon steel.
Article contributed by Rade Knezevic, Business Development Manager, Parker Hannifin Industrial Cylinder Division
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