Thread Identification Chart: BSP, NPT, ORFS and JIC

The thread flank angle and the sealing-seat angle describe different features. A BSP thread's 55° flank angle does not identify the cone used by a particular BSP hose swivel. Likewise, the JIC 37° designation concerns its flare seat. Keep these measurements separate in your inspection notes.

Isolate the equipment and release stored hydraulic energy using its maintenance procedure before disconnecting anything. Label both ends and record the circuit reference. Clean the sample sufficiently to see the geometry without grinding, filing or reshaping a sealing surface.

Photograph the side profile, the threaded end and the seal area. Include a scale and clear markings where available. An overview of a dirty coupling rarely provides enough detail for a supplier to distinguish a cone seat from a face seal.

Use a caliper to compare the diameter at several full threads. A parallel thread remains substantially constant, while a tapered thread changes along its length. Record how and where you measured, because a tapered-thread reading depends on the measurement position.

Measure the male thread outside diameter or the female opening as appropriate, then use a thread pitch gauge. Record threads per inch for the relevant inch thread, or millimetre pitch for a metric thread. Match the observations against a current identification table; nominal pipe size is not simply the measured thread diameter.

If more than one candidate remains, retain all the measurements and inspect the sealing geometry. Do not choose the nearest-looking entry to finish the paperwork. Worn threads and incomplete measurements are reasons to request a sample review.

Use a suitable seat gauge when the connection seals on a cone. For a face seal, inspect the flat face and groove position. An O-ring near a port shoulder is a different arrangement from an O-ring on an ORFS face. Examine both mating components rather than classifying only the loose hose end.

Check whether the fitting is male or female, fixed or swivel, straight or angled. A swivel nut can assist installation without making the assembly suitable for continuous rotation. Record the hose-side requirement separately from the machine-side thread.

BSP and NPT are not interchangeable. Similar diameter or partial engagement does not make their forms compatible. JIC and other flare systems can also appear alike, so do not infer the seat from a nut's appearance. Sealant cannot correct a mismatched cone or damaged flat face.

Prepare the enquiry with the identified connection family, measured dimensions, seat information and photographs. Keep uncertain interfaces flagged until the supplier and maintenance team resolve them. A correct chart narrows the search; the final component drawing and application requirements establish what should be supplied.