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Fittings and Adapters

Hydraulic hose fittings and adapters are critical components that literally make the connection in all hydraulic systems. In any application, finding the right hydraulic hose is only half of the battle; the second and arguably more important part is ensuring that you utilize the right fittings and adapters in your hydraulic system. A hydraulic system is only as good as its weakest link so it’s incredibly important to utilize the right hose fittings and adapters when making connections as different threads, materials and standards equal different pressure ratings and chemical compatibility.

Fittings and adapters connect the parts within a hydraulic assembly and allow the media (hydraulic fluid, water, petroleum, etc) to flow throughout safely and efficiently. While hydraulic fittings and hydraulic adapters are often talked about interchangeably, there are important differences between the two. Hydraulic fittings connect hoses and tubes to each other and to the central components of your hydraulic system, such as an engine cylinder or pump.

Hydraulic adapters, however, are responsible for connecting components with different end sizes or thread type, such as two hose fittings with different types of standards or threads, allowing these parts to function seamlessly together within the same system. Both fittings and adapters are incredibly important, as together they prevent leaks and spontaneous pressure changes while allowing for more variation and efficiency in the designs of fluid conveyance systems. Hydraulic fittings and adapters are undeniably crucial to hydraulic operations in any industry. Due to this overwhelming demand, there are many different types of fittings and adapters on the market. Both hydraulic fittings and adapters can come in a variety of different metals, shapes, threads, and connection styles. 

Fittings are commonly offered in steel, stainless steel, brass, and even plastic, while adapters are usually brass, carbon steel or stainless steel.

These connectors can also have special features, such as Danfoss Power Solution’s Dura-Kote™ plating technology that they use on their fittings and adapters to dramatically increase corrosion resistance.

With all of these options, it can feel impossible to decipher which ones are best suited for your needs. That’s where Omni Services can help. With over 45 years of experience as a leading distributor of hydraulic hose and fittings, Omni Services is uniquely positioned to assist you with all of your hydraulic needs. The fluid conveyance experts at Omni have designed, manufactured, and assembled every kind of hydraulic assembly imaginable, including highly complex systems used in some of the most rigorous and demanding applications in the world.

We work with premium connector manufactures like SSP, Fitok, Brennan and Danfoss Power Solutions (formerly Eaton Hydraulics) to source the highest quality fittings and adapters available on the market for our customers. So, whether you need a single hydraulic adapter to keep your hydraulic system going, or hundreds of connectors to build a brand-new machine, let the professionals at Omni Services help you navigate to the best possible connectors for your application. Learn more about some of the most popular types of fittings and adapters from our brief descriptions below, and feel free to reach out with any further questions – we would love to help in any way we can!

Popular Types of Fittings

Tube Fittings
Tube Fittings are a type of compression fitting used to connect sections of tubing together (hard or soft wall), and can also be used to connect pipes and hoses into a system. These fittings are usually employed in high-purity processes like pharmaceutical manufacturing and precision gas

  • Working Pressure Range: Vacuum to 12,100 psig (Instrumentation Tube Fittings); Vacuum to 9,200 psig (Industrial Tube Fittings)
  • Temperature Range: – 425° to 1200°F
  • Materials: 316 SS, Alloy 400, C-276, Brass, Carbon Steel (Instrumentation); 316/316L Stainless Steel, Brass and Alloy 400 Standard (Industrial).

Weld Fitting
Weld fittings are used for permanent fitting placements, as they are welded into the hydraulic system after placement for the strongest possible seal. These fittings are typically used in high pressure, high temperature, or hazardous material applications that require heavy-duty corrosion
and vibration resistance.

  • Working Pressure Range: Vacuum to 15,000 psig
  • Temperature Range: – 425° to 1200°F
  • Materials: 316/316L Stainless Steel, Alloy 400.

Crimp and Swage fittings:
Crimp fittings permanently attach to rubber and thermoplastic hydraulic hoses. This connection is made by utilizing a crimp or swage machine to compress the teeth inside of the collar of the fitting through the cover of the hose and into the reinforcement layer of the hose. When done
property this creates a permanent and secure connection to the hose.

  • Working Pressure range: 250-10,000psig
  • Temperature: -425º – 1200ºF
  • Materials: Steel, Stainless Steel, Brass

Reusable Fittings:
Field-attachable or “reusable” style fittings can be coupled with the hose using only a wrench and a vise versus a mechanical attachment method like a crimp machine. This makes the reusable fitting valuable in situations where access to crimp equipment is hard to get to. Additionally reusable fittings like the name implies can be used multiple times extending the life of the fitting.

Popular Types of Adapters

Metric Adapters
Metric adapters are metal adapters that feature a combination of male and female ends, one of which being a metric thread and the other being a standard thread. This design allows pipes and hoses with metric threads to be combined with parts that use standard threads, or vice versa.

SAE Adapters
SAE adapters are adapters manufactured to specifications set by the Society of Automotive Engineers and are typically used in low-pressure applications.

JIC Adapters
JIC adapters are manufactured to specifications of the Joint Industrial Council and are utilized in most fluid conveyance systems.

NPT (National Pipe Thread) adapters are threaded adapters that include male and female threaded sides, most used in applications involving gasses.

Common Fitting and Adapter Standards

SAE – Standard:

NPT: National Pipe Tapered (NPT) is a U.S. standard for tapered threads used on pipes and fittings. NPT fittings are used to seal pipes for fluid and gas transfer and should be used with an appropriate pipe dope or sealant to create a leak free connection. The nominal pipe size can be identified by physically measuring the thread diameter, then subtracting 1/4″.

NPTF: National Pipe Tapered Fuel (NPTF) connections are widely used in fluid power systems. They have a tapered thread and seal by the deformation of the threads when tightened.

JIC 37°: JIC connections are common in most fluid power systems. Both male and female components have 37° seats. The seal is made when contact is made between the male flare and female coned seat. This is also considered a mechanical connection.

SAE J512 45°: SAE 45° connections are commonly used in automotive, refrigeration and truck pipe systems and are typically made of brass material. The male and female connections have 45° seats, where the seal is make where the male flare and the female cone meet. This is a
mechanical connection similar to JIC.

O-Ring Boss: O-Ring Boss (ORB) is recommended for leak prevention in medium and high pressure hydraulic systems. The male connection is a straight thread with an O-ring. The female port has a straight thread and a machined surface with a chamfer where the O-ring seats. It seals
when the O-ring is compressed into the chamfer when mating the male connection. This is considered a mechanical connection. 

O-Ring Face Seal: O-Ring Face Seal (ORFS) connections are considered to be superior for leak control. The male connector has a straight thread and an O-ring in the face. The female has a straight thread and a machined flat face. The seal takes place by compressing the O-ring onto the
flat face of the female. The threads maintain the connection mechanically. 

Flange Fittings: Flange fittings are used to connect high pressure hose lines to female ports. There are two different flange offerings which corollate with different pressure ratings for these connections: Code 61 which is considered the standard series and Code 62 which is rated to 6000 PSI. The design is the same for each series, the difference lies in flange head diameters and bolt hole spacing which are larger for the 6000 PSI high pressure Code 62 connection. The female port of the fitting is a smooth, un-threaded port with four bolt holes set in a rectangular pattern around the port. The male is a flanged head with a groove for an O-ring and either split or captive flange halves and bolt holes which match the port. The seal is made where the O-ring is compressed between the flanged head and the flat surface of the port. The connection is held by threaded bolts.


DIN: DIN is a common metric style connection in hydraulic systems. The male connector has a straight metric thread with a 60° angle on the recessed cone. The female has a straight thread with a seat that is a tapered nose. The contact of the cone of the male and the tapered nose of the female flareless swivel is where the seal takes place.  DIN 3902 Series is a common male with three different possible female halves. The straight metric thread male has a 24° angle. Its recessed counter-bore matches the tube O.D. it is connected to. The female may be one of the

  • A tube, nut and ferrule (compression style)
  • A tapered nose flareless swivel
  • A tapered nose flareless swivel with a DKO style O-ring in the nose


British Standard Pipe (BSP) and British Standard Tapered Pipe (BSPT): connections are comparable to NPT, except most sizes have a different thread pitch, plus the OD’s and thread form are close, but not the same. Sealing takes place by deformation of the threads. Because of this, thread sealants are recommended when securing these connections.

British Standard Parallel (BSPP): BSPP male connection is comparable to NPSM male except most sizes have a different thread pitch. A seal is made using metal to metal angled surfaces or a combination of metal to metal and an O-ring. This type of connection is similar but not interchangeable with the American NPSM male. The female swivel BSPP has a tapered nose flareless swivel where the seal occurs on the cone seat of the male connector.


JIS Tapered Pipe: JIS has metric threads per JIS B 0203. These are JIS tapered threads and are comparable to the design of BSPT connections in their dimensions and appearance. JIS tapered thread connections are interchangeable with BSPT connections.

JIS 30º Male Inverted: JIS 30° Male Inverted Seat connections are parallel pipe threads per JIS B 0202. JIS parallel connections are comparable to BSPP connections. JIS parallel thread connections are interchangeable with BSPP connections.

FIS Female Cone: Seat are parallel pipe threads per JIS B 0202. Japanese JIS 30° flare connections are comparable to American SAE 37° flare connections in application and sealing principals. Yet, JIS 30° flare angle and dimensions are different with threads that are similar to BSPP.

Komatsu: Komatsu couplings contain both a 30° flare and metric threads. The seal takes place between the male flare and female coned seat.

Kobelco: Kobelco couplings contains French Millimetric Threads which are very similar to metric threads and feature a 1.5 mm pitch. Sealing takes place between the 24° chamfer seat in the male connector and the respective sealing area on the female ball or cone.


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