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Types of metal hydraulic hose and tube fittings
Steel is the most basic type of metal hydraulic fitting. It is a strong, durable metal with a high heat resistance. However, while steel is characterized as strong and durable, it has little resistance to corrosion. Therefore, steel is typically alloyed with other metals to improve its corrosion resistance.
- Carbon Steel
Carbon steel, an alloy of iron and carbon, is typically alloyed with other metals to provide absolute maximum strength and durability. This type of metal hose fitting is ideal for extreme temperature applications or where there is the possibility of external force being exerted against the fitting. Because of the high strength and pressure ratings, as well as the relatively low cost of carbon steel, these fittings are used widely in industrial, construction and agricultural hydraulic equipment.
Brass is a strong, durable and corrosion resistant alloy of copper and zinc with a vast temperature range of –325° to 400° F (–198° to 204° C). Brass fittings are typically used for smaller compression and threaded fittings due to their machinability. While brass can accommodate pressures to 3000 psi depending on design and size, most applications are rated for low temperatures and pressures.
Aluminum is alloyed with zinc, copper, silicon, manganese and other metals to improve strength and hardness. Aluminum is typically characterized by low tensile strength and is used for its properties of corrosion resistance and low density in low-pressure applications, however, the performance of the fittings depends on the grade and heat treatment. Aluminum fittings are common where light weight is imperative, such as aerospace, military, and automotive hydraulic systems. Corrosion resistance is improved by an anodized external finish, which makes the surface harder for wear and abrasion resistance. Aluminum fittings have good media compatibility and are frequently used with plastic and aluminum tubing.
Why stainless steel is your best option
Corrosive environments require "tough" fittings
For corrosive environments, stainless steel is recommended because the interaction between its alloying elements and the environment doesn’t cause rust. Stainless steel contains iron, chromium, manganese, silicon, carbon and, in many cases, significant amounts of nickel and molybdenum. These elements react with oxygen from water and air to form a very thin, stable film that consists of such corrosion products as metal oxides and hydroxides. Chromium plays a dominant role in reacting with oxygen to form this corrosion product film. In fact, all stainless steels contain at least 10 percent chromium.
The four reasons why
So, why choose stainless steel fittings for a hydraulic hose application? Here are four reasons:
- It contains the strength and durability of steel and has a strong chemical and corrosion resistance that suits hydraulic applications, especially where the fluid or surrounding environment is corrosive.
- Its enhanced corrosion resistance extends the service life of a hose assembly
- Stainless steel fittings have a temperature range of –425° to 1200°F (–254° to 649°C)
- Its toughness is significantly better than that of carbon steels at low temperatures. Industrial stainless steel fittings are often rated to 10,000 psi, and specially designed stainless steel fittings can have pressure ratings up to 20,000 psi.
Because of its high durability, strength and corrosion resistance, stainless steel is typically more expensive than fittings made from other materials. However, due to the corrosive environment, many applications require fittings to be corrosion resistance such as:
- oil and gas / offshore equipment
- chemical processing
- food manufacturing
- medical and instrumentation
- agricultural fertilizer
- marine applications
Parker’s stainless steel hose fittings withstand the corrosive elements better than any other metal typically used for hydraulic hose systems. Better corrosion resistance means extended service life of your hose assembly. Our stainless steel and fittings are available in a variety of styles, such as Code 61, Code 62, JIC, NPTF, ORFS, SAE, and DIN. We have fitting configurations from a -4 (1/4") up to -32 (2") to meet the needs of any application. For additional information, reference our .
Article contributed by Kyri McDonough, marketing services manager at Hose Products Division, Parker Hannifin.
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