Gas Leak Returned After Weld Repair: Corroded Section

Refrigerant loss returning some months after a previous repair, with the new escape point close to where the old one was. The pipework in that area is visibly corroded along its length. Everything else on the system is behaving normally.

A second failure beside the first is not bad luck and should not be treated as one. It says the condition that produced the original leak was never local to the point that leaked. Assessing the pipe means looking along the whole exposed length rather than at the spot in front of you. The useful measure is how much of that length looks the same as the section that failed.

Copper corroding from the outside loses wall thickness across whatever length is exposed to the same conditions. A leak appears wherever the wall becomes thinnest first, and repairing that point restores it locally while leaving the rest of the run just as thin. Heat from the repair itself can accelerate the metal immediately beside it. The pipe is failing as a length, and it is being repaired as a point.

The corroded section is replaced rather than patched again. The new pipe is insulated and protected properly against the conditions that caused the failure. This is the decision worth reaching sooner rather than later, because a third patch costs more than the section replacement and buys the same few months the second one bought.