Identify 11 HGW Hydraulic Fitting Families by Their Seal Location

The fastest way to narrow a hydraulic replacement is to find where the connection contains pressure. Thread diameter is secondary: some threads seal by interference, while others only clamp a flare, face, ferrule, washer or O-ring.

HGW organizes common products into 11 practical families. Grouping them by seal location makes near-match errors easier to detect.

Metal-seat and tube-grip connections

37-degree JIC fittings use a machined flare seat with a unified straight retaining thread. Inspect the cone angle and surface, then identify straight, elbow, tee, swivel or bulkhead body. A 45-degree plumbing flare or 30-degree seat is not JIC.

NPSM pipe swivel adapters use a straight pipe thread in a swivel arrangement and seal at the specified mating seat, not by NPT-style taper interference. Confirm nominal pipe size, swivel seat and the connection at the fixed end.

Flareless bite-type tube fittings use a sleeve or ferrule against an unflared tube. Tube outside diameter, wall, material, hardness and preparation belong to the fitting system. SAE inch and metric/DIN tube systems must not be blended because both are called flareless.

Common confusion in this group comes from relying on the retaining thread. A JIC nut can hide its flare when photographed from the side, and an NPSM swivel may be mislabeled as straight NPT. Request a face-on image and measure the seat before choosing an adapter.

Elastomer and gasket-sealed connections

SAE O-ring boss fittings place an O-ring at a straight-thread port. Identify fixed or adjustable stud style, port spotface and correct seal. The thread retains the body; it does not replace the boss O-ring.

ORFS fittings compress a captured face O-ring against a flat mating surface. Check groove, seal compound, tube or hose face and actual thread table. A dash number commonly refers to conductor size and is not a direct thread-diameter calculation.

Flange adapters and plugs seal at a flange head or port with the specified O-ring and clamp arrangement. Separate Code 61, Code 62 and OEM-specific forms by dimensions, bolt pattern and design series. Similar four-bolt appearance is insufficient.

Elastomer identification belongs on the order when fluid or temperature is not general mineral-oil service. Record compound or approved part number, not color alone. A replacement O-ring should fill the specified groove without stretch, twist or extrusion.

Pipe-thread families

NPT fittings use a 60-degree tapered pipe thread. Confirm NPT versus NPTF, nominal size, male/female form, engagement and approved sealant. Avoid forcing a BSPT near-match into the port.

BSP fittings include tapered BSPT and parallel BSPP forms, commonly with a 55-degree thread profile. BSPT uses thread interference under its specified sealing practice. BSPP hydraulic ports depend on a washer, O-ring, cone or another defined seat.

Compare NPT and BSPT with a pitch and profile gauge after cleaning the part. Some nominal sizes have close diameters and can engage several turns while loading the wrong flanks. Sealant can delay the resulting leak, which makes controlled identification more important than a short pressure test.

Metric and regional connections

Metric/DIN 2353 fittings often refer to 24-degree tube systems, but metric threads also appear on O-ring ports and other seat forms. Record pitch, tube outside diameter, series and port form. JIS and OEM-specific 30-degree connections are not generic DIN fittings.

The machine origin helps guide inspection but cannot replace measurement. European, Japanese and North American equipment can contain adapters added during prior service.

Metric straight threads may retain DIN tube ends, ISO O-ring ports, flat-face seals or manufacturer-specific seats. Add seat angle and port cross-section to the record. “M18” or another diameter-and-pitch label does not define the pressure seal.

Hose and fabricated interfaces

Hose barb adapters retain compatible hose over a shaped stem using the approved clamp, crimp or other method. Hose inside diameter, reinforcement, fluid and pressure determine suitability. A utility barb is not a high-pressure hydraulic hose end.

Weld-on tube and hose adapters become part of a fabricated pressure boundary. Define weld end, bore, material, downstream connection and qualified welding, inspection and test procedure. Do not weld a plated or threaded fitting that was not designed for it.

Barbs and weld ends illustrate why a catalog family may describe only one side. The opposite end can be NPT, JIC, ORB, BSP, metric or another interface. Record both ends in a consistent order so a database search does not return the mirror-image connection.

Separate body function from seal family

A reducer changes size; a union joins like interfaces; a bulkhead passes through a panel; a tee or cross creates branches. Swivels support assembly or motion only when designed for that duty. These functions can be combined with several seal families.

Measure centerline dimensions and clocking where an elbow stack fits a tight machine envelope. Replacing two adapters with one body can reduce joints, but only after the new part preserves both standards, flow area and tool access.

Use a repeatable purchasing evidence packet

For an unidentified connection, provide machine model and location, clear photos of both mating halves, measured thread diameter and pitch, seat or groove image, tube or hose dimensions and desired body orientation. State material, fluid, pressure and temperature basis when known.

Keep the final drawing, HGW part number and verification result with the equipment record. This turns a one-time identification into controlled replenishment and prevents later buyers from starting with a worn sample alone.

Record both ends before choosing the body

Photograph and measure the removed part and the mating components. Record thread, pitch, taper, seat, seal, conductor size, material, pressure basis and wrench clearance. Then select body geometry without forcing the hose or tube out of alignment.

These 11 groups are a purchasing map, not a claim that every fitting belongs to HGW or that one family replaces another. The correct family is the one whose two interfaces reproduce the specified seals already designed into the equipment.