Local and state government organizations allow the most qualified contractor or bidder to maintain and install their needed hydraulic fittings. The application of government fittings ranges from standard fitting repairs for local government-run buildings to highly customized hydraulic fittings for state or national government run construction or research projects.
Uses for Government Fittings
Government fittings include the following types and uses:
Pipe fittings: These are the most basic and common fitting components available. They rely on the stress generated when both ends of the fitting are forced together. This creates a metal-to-metal wedge that is usually acceptable for most low pressure government applications. They are available in American, British and metric taper measurements. Pipe fittings are still commonly used for high static pressure systems but are less reliable when exposed to the dynamic pressures of a hydraulic system, which makes them least useful for government hydraulic applications.
Flare fittings: 37 degree flare fittings are the most commonly used fitting component in all hydraulic applications, including government specific projects. They conform to SAE and ISO standards, which smaller government fittings contracts usually adhere to. Certain types of flare types meet a military grade MIL-F 18866 standard that is required for certain government applications. Flare fittings remain the most economical choice of fitment type that can operate in pressure ranging from 1,500 to 7,000 psi.
Flareless fittings: This fitting type is often used because it requires less tube preparation and can withstand vibration better than most other fitting types. Highly sensitive government applications may include the use of bite type flareless fittings that can handle pressures of up to 9,000 psi and still operate well under high vacuum or small molecule gas conditions.
O-ring fittings: O-ring boss fittings and face seals are capable of providing highly dependable leak-free hydraulic connections for government applications of up to 6,000 psi. The o-ring fittings are based on a reliable seal between the metal and seal material, which is usually made out of nitrile or fluorocarbon. This type of fitting is often used when custom components are required in order to operate in an environment containing a certain amount of pressure, heat and vibration.
Types of Government Fittings
The various models of government accepted fittings can be ordered in several different material types. They are:
Brass: Brass is common in industrial and residential applications and may be used for government fittings that do not have to adhere to a specialized standard of quality. Brass is used primarily because of its availability, moderately good strength, cold ductility and corrosion resistance properties.
Steel alloys: This is the most traditional type of piping and fitting material used for government grade applications. Each fitting project will often require a precise type of steel alloy to match the needs of the project. For example, medium carbon steel alloy contains excellent surface wear resistance properties for moderate stress applications. Cold rolled steel offers excellent ductility for hydraulic hoses, inserts and coupling components. Many other grades of carbon steel alloys can be used based on your needs.
Stainless steel: This type of fitting material is the best for applications requiring material that is highly resistant to oxidation and corrosion. Hydraulic system requirements must be carefully considered before selecting the right grade of stainless steel for use.
Elastomeric compounds: Elastomers are found in o-ring seal applications. Polyurethane material such as Molythane or nitrile rubber is commonly used for government fitting systems that handle pressures of 5,000 psi or lower. Fluoroelastomer is a higher grade compound ideal for high quality government fitting applications because it can withstand temperatures of up to 400 degrees Fahrenheit and is resistant to a majority of hydraulic fluid types.
Who Needs Government Fittings
Choosing the right government fittings generally starts with a look at the required pipe fitting standards. The standard used, which may include the British standard, ISO, JIS, NP, ASME or even Army-Navy protocol, will dictate the types of fittings you will be able to use.
You must thoroughly consider material compatibility and the hydraulic pressure system conditions of the government application before selecting your pipe fittings. Check the compatibility of your preferred pipe fitting material with the hydraulic fluid that will be used in the application. This can be based on type of hydraulic fluid being used, its viscosity grade and the presence of detergents and dispersants as well as anti-wear additives.
The material compatibility must be cross referenced with the temperature and pressure specifications. This is particularly important in ensuring a leak free hydraulic system. Certain government fittings that are also used in other industries are generally only rated as standard 3,000 psi fittings.
Specialty fittings may be required to withstand pressure levels over 7,000 psi and occasional operating temperatures of over 400 degrees Fahrenheit. Pressure and temperature conditions may also require the use of SAE o-rings and face seals with specific elastomeric or non-elastomeric material. The type of seal material used may vary depending on budget costs, temperature conditions and the material’s wear resistance properties.