Web exclusive — Improved Corrosion Resistant Cartridge Valves

Figure 1: A collection of corrosion resistant cartridge valves.

Sun has been making corrosion resistant models of cartridge valves since 2003. At first in classic Sun fashion, one corrosion resistant model was made to address a unique problem for a single customer. Then another model was made to address the unique needs of a second customer. Over time the number of interested customers grew, and customers expressed interest in a greater number of models. By 2008 Sun offered a fair selection of corrosion resistant models. However, even more were needed, and Sun thought pricing could be lower. A given, availability needed to be assured. So in 2009 designs were improved and manufacturing of corrosion resistant models was moved to Sarasota, Florida, where all Sun's standard cartridge valves have been made since 1970.

The most significant changes in the corrosion resistant cartridge valve models pertain to materials. Sun chose lean duplex stainless steel (LDX) for cartridge valve bodies after material studies and extensive testing. LDX stainless steel is twice as strong as 316 stainless, and it is similarly corrosion resistant.

Figure 2: Corrosion resistant cartridge valve body after nearly 4000 hours in salt fog.

Depending on whether strength or resistance to galling is paramount, adjustment screws are titanium or silicon brass, and when especially aggressive environments require additional protection, stainless steel caps can be fitted to completely cover the screws.

Figure 3: Available protective cap for especially aggressive environments.

The internal parts of corrosion resistant models are heat treated carbon steel for high strength and low wear, the same as standard models. Corrosion resistant models are expected to be used in typical hydraulic systems that are exposed to harsh environments. They are not resistant to internal corrosion caused by operating fluids. For instance, they are not suitable for hydraulic systems using water as the operating fluid.

The oil and gas industry has readily accepted Sun corrosion resistant cartridge valves for use on hydraulic power units and throughout the balance of the hydraulic system.

Relief valves limit pressure and protect cylinders, motors, and fixed and pressure compensated pumps. Sequence valves make sure one operation takes place before another. For example, they are applied when work pieces must be clamped before they are drilled or otherwise machined. Reducing valves permit various operating pressures in a single hydraulic circuit. Check valves allow multiple pumps to operate in parallel. Logic elements control special pressure, directional, and load holding functions. Counterbalance valves and pilot operated check valves control and hold loads being driven by cylinders and motors. Flow control valves regulate the speed of cylinders and motors. Flow divider and combiner valves separate single flow streams into multiple flow streams, and vice versa. Directional control valves turn flow on and off, to extend and retract cylinders, and to rotate motors clockwise and counterclockwise.

Sun valves are used to control clamp cylinders, latch cylinders, lift cylinders and motors, lock cylinders, propel motors, reel motors, and winch motors. In the harsh environment of the Gulf of Mexico on offshore oil and natural gas platforms, where hydraulic components and systems are exposed to the sea and salt air, it has been proven Sun's corrosion resistant cartridge valves last longer than standard zinc plated steel valves, even when paint or special coatings are applied in an attempt to protect the steel valves.

Figure 5: New standard zinc plated steel cartridge valve and one at the end of its life of service in a harsh environment.

Along with valves simply lasting longer, valve adjustment screws of corrosion resistant models remain free from corrosion and growth, and remain easy to adjust throughout the life of the valve.

Industries other than oil and gas have also accepted Sun's corrosion resistant cartridge valves. In the marine industry corrosion resistant models have been applied to open and close the locks and sluice gates of waterways and flood defenses in England; to lift, lower, and stow lifeboats on ships; to lift, lower, and stow dinghies and other auxiliary craft on yachts; to fold and unfold, extend and retract passarelles and other boarding equipment on commercial and recreational vessels. Corrosion resistant models have been applied in test equipment and on test stands. They have been applied to control the rudders of rescue submarines.Corrosion resistant models have been applied in medical equipment.

The hydraulic performance of Sun's corrosion resistant cartridge valves matches the performance of standard models, with flow capacities to 200 gpm (760 l/min) and pressure ratings to 5,000 psi (350 bar).Visit www.sunhydraulics.com for specific performance curves, pricing, and other information.Order Sun’s latest Corrosion Resistant Cartridge Valve Brochure through the Literature Request page on the web site if you would like one. Call your local Sun Authorized Distributor, who can be identified on the web site, for expert application assistance.