Common Hydraulic Hose Fitting Types and Where They Fit
HGW Hydraulics on May 31st 2022
Hydraulic hose fittings connect hose, tube, pipe, and component ports. Most styles are built around industrial standards, so identification should start with the connection standard, sealing method, and the application pressure.
Common standards and naming systems include DIN, ISO, JIC, SAE, and military specifications. The fitting style determines how the seal is made and what tube or hose preparation is required.
SAE 37 Degree Flare and ORFS Families
SAE J514 covers many 37 degree flare hydraulic tube fittings and adapters. SAE J1453 and ISO 8434-3 cover O-ring face seal fittings. These families also include adapter unions, plugs, pipe fittings, and related connection parts.
Steel J514 fittings are used across many fluid power applications, often in pressure ranges from about 1,500 to 6,000 PSI depending on size, material, configuration, and system conditions. Stainless steel and other alloys may support more demanding service when the fitting is designed and rated for it.
37 Degree Flare Fittings
The 37 degree flare connection is one of the most common flare fitting styles. The tube end is flared, then sealed between the fitting nose and the sleeve as the nut is tightened.
This style is widely used with thin to medium wall tubing. It is common in hydraulic systems that need a reusable metal-to-metal seal and a broad range of shapes, sizes, and materials.
Working pressure depends on the material, size, and shape of the fitting. Straight fittings, elbows, and tees may not carry the same rating even when the nominal size is the same.
AN 37 Degree Flare Fittings
AN flare fittings also use a 37 degree flare. The tube is flared before installation, then the sleeve and nut draw the flare against the male cone to create the seal.
The sleeve supports the flare and helps distribute vibration around the connection. AN-style specifications use tighter thread and tolerance requirements, which is why they are associated with high-performance and aerospace-style applications.
24 Degree Flareless Bite-Type Fittings
24 degree flareless compression fittings are also widely used, especially in European-style hydraulic systems. This connection uses a body, nut, and ferrule rather than a flared tube end.
As the nut is tightened, the ferrule bites into the tube OD and seals against the 24 degree tapered seat. This can be useful where a tube is too thick to flare or where severe conditions require a bite-type connection.
Some flareless fittings are built for higher-pressure systems and strong vibration resistance. The correct series, tube wall thickness, torque method, and fitting standard should always be checked before substitution.