Metal Matters: How to Combat Hydraulic Fitting Corrosion
Friday, March 17, 2017
Refined metals (such as steel, stainless steel, and brass) do not naturally occur and over time tend to revert to their more stable mineral forms. This process is called corrosion – the gradual destruction of refined metals by chemical and/or electrochemical reactions within their environment. While considered a natural, inevitable process, it’s still a consideration to production and product development. Hydraulic fitting manufacturers, like Air-Way Manufacturing, prevent corrosion by controlling the design, protective coating, and material selection of every fitting made.
When selecting the right manufacturing material and/or protective plating for hydraulic fittings, consider the type of fluid that will be flowing through the fitting, at what pressure, and what temperature both the internal and external environment will be functioning at.
Refined Metal Comparisons
Hydraulic fitting materials must have the right strength and corrosion resistance to safely handle high pressure environments typical of hydraulic systems. Metal fittings are generally used with most hydraulic systems due to their high-pressure ratings. Some plastics can have a higher resistance to corrosion, but their lower strength and durability make them poorly suited for hydraulic systems.
Four common metal materials used for fittings are carbon steel, stainless steel, brass, and aluminum.
- Carbon Steel: Carbon steel is durable, strong, and maintains a high resistance to heat. An alloy of iron and carbon, carbon steel hydraulic fittings are lower cost and frequently used in the agricultural, industrial, and construction sector because of their affinity to high pressure, high strength environments.
- Stainless Steel: Stainless steel displays the same strength and durability of carbon steel while also providing excellent corrosion resistance. It’s considered the most suitable material for hydraulic fitting applications where the fluids and/or external environments are highly corrosive. At low pressure specifically, stainless steel is your best bet.
- Brass: Brass has a moderate strength level with good corrosion resistance in lower pressure situations. This kind of refined metal is typically used for smaller compression and threaded fittings. It is not recommended for temperatures higher than 400 degrees as it becomes soft and loses strength.
- Aluminum: Aluminum is light weight and corrosion resistant. It’s commonly used in low density, low pressure applications and can be alloyed with zinc, copper, silicon, etc. to improve strength. Aluminum can handle a higher pressure than brass and is a good choice for lightweight applications.
Corrosion Resistant Plating and Coatings
External plating or coating can be applied to carbon steel hydraulic fittings to extend their life in highly corrosive environments that use harsh medias such as salt sprays and fertilizers.
At Air-Way Global Manufacturing we offer three primary plating options:
- Electroless nickel
- Zinc nickel
- Electrodeposited zinc.
Standard to all steel hydraulic fittings manufactured by Air-Way, the new electrodeposited zinc trivalent plating offers a significantly higher corrosion resistance rating when compared to its predecessor – zinc with hexavalent chromate. Withstanding white corrosion for 240 hours and red corrosion for 360 hours, its longevity and high resistance to corrosion make it an excellent coating for all our steel fittings.
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