Hydraulic Fitting Standards Guide: NPT, ORB, JIC, ORFS, BSP, DIN, JIS, and Ferrules

Hydraulic fittings are built around connection standards. Threads, seats, O-rings, ferrules, flanges, and cone angles determine how the joint seals, not just whether the parts appear to screw together.

American Connection Families

NPT uses tapered pipe threads and often needs sealant. NPTF is also tapered but is designed for a dryseal metal-to-metal thread seal in fluid power service. NPSM uses straight threads with a 30 degree mechanical seat. SAE-related fittings include ORB, JIC 37 degree flare, SAE 45 degree flare, ORFS, and 4-bolt flange connections.

ORB, JIC, and ORFS

ORB fittings use straight threads and an O-ring at the port. JIC fittings seal on a 37 degree metal flare. ORFS fittings seal with an O-ring on a flat face and are often chosen where vibration and leakage control matter.

British, ISO, DIN, and JIS Standards

BSP connections include BSPT tapered threads and BSPP parallel threads. ISO and SAE flange or metric port designs may use O-rings and metric or inch bolts. DIN connections include 60 degree cone, 24 degree cone, DKO O-ring, and metric port styles. JIS fittings include tapered pipe, 30 degree seat, and 4-bolt flange forms such as Code 61 and Code 62.

Instrumentation Ferrule Fittings

Instrumentation fittings may use single ferrule or double ferrule designs to grip and seal tubing in fluid or gas transfer systems. Selection should match the standard, pressure, tube material, seal type, and maintenance requirement before installation.