🔧 This article is part of the FluidForce NZ Hydraulic Hose How-To & Troubleshooting Guides.
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Common Mistakes When Matching Hydraulic Fittings
And how to avoid them
Hydraulic fittings often look similar but differ by just a few degrees or thread sizes — leading to leaks, stripping, or blowouts. Here’s what to watch for:
Reusing Old Fittings on New Hose
Problem: Worn ferrules or stretched inserts can fail under pressure.
Avoid it: Always use new fittings when assembling new hose lines.
Mixing Thread Standards
Problem: BSP and NPT have different thread pitches and sealing methods. They may screw together partially but won’t seal under pressure.
Avoid it: Always check for the correct standard before assembly — BSP for NZ/Australia, NPT for North America
Ignoring Seat Angle
Problem: A 37° JIC flare won’t properly seal against a 30° BSP seat.
Avoid it: Confirm seat angles with a gauge — even a few degrees off will cause micro-leaks.
Wrong Hose Size or Fitting Combination
Problem: Using undersized fittings reduces flow and increases pressure drop.
Avoid it: Match hose ID to fitting ID for correct flow rating
Over-Tightening
Problem: Excess torque can distort metal flares or crush O-rings.
Avoid it: Use a torque wrench or follow the manufacturer’s torque guide.
Using Sealant on O-Ring or Flare Fittings
Problem: PTFE tape or thread compound can block ports or cause contamination.
Avoid it: Only use sealant on tapered thread fittings like NPT or BSPT.
Need more help?
If you can’t find the information you need, or want help with your specific set up, get in touch.