CONDITION
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POSSIBLE CAUSES
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RECOMMENDATIONS
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- Tube nut binds to tube flare, or tube nut cannot engage the fitting body
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- Flare too large or tube wall too heavy
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- Flare new tube end using proper flare diameters
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- Flare is out-of-round (lopsided)
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- Re-cut tube, reasonably square, to 90º ± 1º and flare new tube end
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- Nicks, scratches, pock marks on tube flare of fitting
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- Contaminants on tube ID or flaring cone/pin prior to flaring
- Worn/damaged flaring cone/pin
- Poor-quality tube
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- Flare new tube end using proper tube preparation techniques
- Assure that flare cone is clean
- Replace poor-quality tube
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- Poor-quality welded tube
- Work-hardened tube
- Tube not annealed (too hard)
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- Flare new tube end using appropriate
tube (e.g.,fully annealed) and tube cutting methods
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- Tube nut bottoms out before seats are mated properly
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- 45º flare tube nut used
- Tube sleeve was omitted
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- Use appropriate 37° flare components (body, nut and sleeve)
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- Immediate leakage from tube nut
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- Connection may not be
tightened properly (if at all)
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- Check joint for appropriate FFWR or torque; re-tighten to spec
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- Tube nut continues to back off or loosen
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- Damaged fitting
- Excessive vibration
- Improper assembly torque
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- Replace damaged fitting
- Re-route or clamp properly
- Assemble to appropriate torque
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- Damaged fitting and/or nose collapse, flow reduction
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- Frequent assembly/disassembly or over-tightening
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- Fitting should be replaced and tightened properly
- Avoid frequent assembly/disassembly
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