One of the most common sources of system leaks is which issue?

• A. Over-tightened nut
• B. Incorrect flare
• C. Dirty tube surface
• D. Wrong solder alloy

Answer: (B)

An incorrect flare is the most common source of leaks because the seal at a flare joint relies on the flare end pressing evenly against the fitting seat. If the flare is not formed correctly—wrong angle, flat spots, cracks, or it isn’t seating flush—the joint can’t seal, and a tiny gap lets fluid escape under pressure. To prevent this, form the flare to the correct shape and size, keep the tube end square and burr-free, inspect for cracks or deformation, and ensure the flare seats evenly as the nut is tightened. While over-tightening, dirt on the tube, or using the wrong solder alloy can cause problems, they don’t guarantee a seal like a proper flare does, so a bad flare remains the leading cause of leaks.