Materials of construction have a long-term impact on the performance of your industrial valve and the overall hydraulic system. When choosing your high-pressure water valve materials, the following factors will help you with your selection:
1. Material Incompatibilities
Understanding material incompatibilities is especially important for those parts of the industrial valve that will come into direct contact with the flow media. These are called the “wetted” areas. These will vary for different types of high-pressure water valves. (While we’re focusing on water-based hydraulic systems, our approach for specifying materials would also apply to systems that use other media.)
The majority of water hydraulic systems are water-based, meaning that they contain a heavy concentration of water mixed with a small percentage of some other additive. Since water is a poor lubricant, water-soluble oil is usually added to improve the lubricity of the water. This helps reduce the wear on seals, bushings, valves and pumps. Glycol is another additive that may improve fire resistance while biocides may be added to inhibit bacterial growth.
Additives may a cause a negative interaction with the valve materials. For example, a water-glycol mix will degrade a polyurethane or polyester seal quite quickly. Similarly, chlorine that is present in some municipal water sources has been known to cause galvanic crevice corrosion in some valve applications.
Helpful tip: To identify potential material incompatibilities, consult the incompatibility charts published by industrial valve, seal and gasket manufacturers. They’ll list common substances and how they interact with their materials of construction.
2. Cleanliness of Flow Media
Of course, it’s well-known that water on its own typically leads to corrosion and will affect valve components over time. But it is also imperative that you consider the cleanliness of the flow media.
Properly maintained closed-loop systems will not typically experience media cleanliness issues. However, open-ended systems, such as those used in descaling operations in steel mills, are a different story. In these systems, the process water that’s recycled through the system contains particles that can have a harmful effect on the wetted areas of the valves. These particles will impinge upon those surfaces and cause excessive wear.
Your materials of construction need to account for potential contaminants in the flow media.
The temperature of the flow media as well as the temperature of the operating environment must be considered. Corrosion will faster at higher temperatures. Additionally, extremes in temperature can cause different materials to expand or contract at different rates. These changes may cause leakage issues, undue binding stress on valve components or seizure.
Want to learn more about how to select the right material for your high-pressure water valve? Download “How to Choose the Proper High-Pressure Water Valve Material“.