QUALITY HYDRAULIC HOSES, FITTINGS & ADAPTORS

🔧 This article is part of the FluidForce NZ Hydraulic Hose How-To & Troubleshooting Guides.
Explore step-by-step instructions, fitting advice, and safety best practices at our Hydraulic Hose How-To Hub.

How to Correctly Measure a Hydraulic Fitting

Incorrect fitting identification is one of the most common causes of leaks. Follow these steps to measure threads and seats accurately.

Use a thread identification gauge:
Match the threads per inch (TPI) or pitch for metric fittings.
Note whether threads are parallel or tapered â€” BSPT and NPT are tapered; BSPP, JIC, and ORFS are parallel.

Use digital calipers to measure the outer diameter (OD) of male threads or the inner diameter (ID) of female threads.
Record the measurement in millimetres for BSP/metric or inches for JIC/NPT.

Use a seat angle gauge to find the sealing surface angle:

37° â†’ JIC
30° â†’ BSP
24° â†’ DIN/Metric
Flat face with O-ring â†’ ORFS
Never assume based on appearance — even small angle differences can cause leaks.

Identify whether sealing is achieved by:
Metal-to-metal contact (flare or cone)
Elastomer seal (O-ring or bonded washer)
This detail determines the correct replacement fitting type.

Compare your measurements to our hydraulic fitting identification chart.

measuring hydraulic fitting with calipers

Need more help?

If you can’t find the information you need, or want help with your specific set up, get in touch.

CALL US EMAIL US