Hydraulic Fitting Types and Applications: ORFS, Caps, Plugs, and Hose Ends

Quick answer

Common hydraulic fitting types include more than threaded adapters. Buyers also run into ORFS fittings, caps, plugs, crimp fittings, field attachable hose ends, and specialty adapters. Each type has a different job, so the replacement should be selected by function first.

The practical order is: identify what the part does, identify how it seals, confirm size and material, then choose the HGW category or custom path.

ORFS fittings for leak control

O-ring face seal fittings use a flat face with an O-ring to create the seal. They are common where vibration, impulse, and leak control matter. The O-ring condition, groove, mating face, and tube or hose end all have to match.

When the old part has a flat face and visible O-ring groove, start with ORFS fittings. Do not confuse ORFS with ORB; both use O-rings, but they seal in different places.

Caps and plugs are not all pressure parts

Caps and plugs may protect threads, keep contamination out during storage, reduce service drips, or close a pressure port. A plastic dust cap is not the same as a pressure-rated hydraulic plug.

Before ordering, decide whether the closure is for protection, temporary service, shipping, or actual hydraulic pressure. Then match thread, seal, material, and pressure requirement.

Crimp fittings and field attachable fittings

Crimp fittings are assembled with the correct hose, stem, ferrule, and crimp specification. Field attachable fittings are used where serviceability matters and the hose/fitting system supports it. Neither should be chosen by thread alone.

For hose end replacement, record hose size, pressure rating, fitting end, body angle, orientation, and whether the assembly needs a specific crimp spec.

Adapters and special shapes

Adapters let buyers connect one family to another, such as JIC to ORB, pipe to JIC, metric to BSP, or flange to threaded connection. The adapter solves a connection problem only if both ends are identified correctly.

Compare the mating ends against JIC, NPT pipe, SAE O-ring boss, Metric / DIN, BSP, and flange adapters.

FAQ

What is the safest way to choose among fitting types?

Identify the job first: sealing, adapting, closing, protecting, or connecting a hose. Then confirm the connection family and size.

Are caps and plugs interchangeable?

Not automatically. Some protect threads only, while others are pressure-rated closures. Match the purpose and seal.

Why do ORFS fittings leak after replacement?

Common causes include damaged O-ring, scratched face, wrong size, poor tube sleeve condition, or a mating face that is not flat and clean.