Fittings can be complicated, but they don’t have to be if you know how to recognize them by,
1) Nominal size – Remember to subtract 1/4″ from the actual size to arrive at nominal size.
2) Determine if thread is tapered or parallel
3) Thread type – Metric, SAE ORBS, SAE ORFS, NPT/ NPTF, NPS/ NPSM, BSPT, BSPP, JIC, JIS, Etc.
4) Thread pitch – Thread per inch, this will vary depending if the fitting is fine thread or coarse thread.
STEP 1 – To identify nominal size, use vernier caliper to measure major diameter of thread and subtract 1/4″ from the measurement to get the nominal size.
STEP 2- Determine if thread is tapered or parallel. Use thread vernier in your thread ID kit or straight edge to do so.
STEP 3 – Determine thread type,
- Metric- Coarse or fine thread
- SAE ORBS- SAE Oring Boss Seal
- SAE ORFS- SAE Oring Face Seal
- NPT/ NPTF- National Pipe Taper / Nation Pipe Taper Fuel (dry seal)
- NPS/ NPSM- Naional Pipe Straight/ National Pipe Straight Mechanical
- BSPT- British Standard Pipe Taper
- BSPP- British Standard Pipe Parallel
- JIC- Joint Industrial Council
- JIS- Japanese Industrial Standard
STEP 4- Use thread ID kit to measure the threads per inches. Be careful to use the standard gauges for standard fittings, and the metric gauges for metric fittings.
Call us for any questions or concerns regarding fittings.
*MB Services and Exporting, Inc. is not an EATON authorized distributor.
The picture taken of the thread ID Kit is the one MB Services and Exporting, Inc. uses in-house to identify the threads we run into.
It is simply being used here for instructional purposes, and so that our readers can get a visual of the kit.