How to find the right Fitting Nuts AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Fitting Nuts
- Fitting type
- Match the joint type exactly: compression (ferrule), 45-degree SAE flare or 37-degree JIC flare. These look alike but seat on different angles and will leak if mixed.
- Tube outside diameter
- Size compression and flare nuts to the tube's actual OD, not nominal pipe size. Tubing is sized by OD. Nominal pipe sizes do not correspond.
- Material compatibility
- Brass for copper water and gas lines. Stainless for corrosive or high-pressure service. Use tube inserts with plastic tubing. Mismatched metals corrode, and soft tubing collapses under a ferrule without an insert.
- Thread compatibility
- The nut must match the body's thread, not just the tube size. Same tube size can carry different body threads across fitting standards.
Brands that matter
- Swagelok: Reference brand for instrumentation compression tube fittings.
- Parker: Major maker of compression, flare and hydraulic tube fittings.
- Anderson Metals: Common brass compression and flare fittings for household plumbing and gas.
What to avoid
- Mixing nuts and ferrules from different compression fitting manufacturers
- Using thread sealant or tape on flare or compression seats, which seal metal to metal
- Reusing flare nuts on a cracked or deformed flare
Questions
Can I reuse a compression nut with a new ferrule?
Often the nut can be reused, but the ferrule is swaged onto the tube, so cut it off and fit a new ferrule matched to the same fitting system.