Scenario;

During routine maintenance you remove old wet insulation from ammonia piping and find both pitting and corrosion. How do you judge or determine whether the pipe should be replaced? Is there a specific code that says a certain amount of corrosion is tolerable, but beyond a certain threshhold the pipe must be replaced?

One person says "There is plenty of metal left in those pipes. Clean and paint them, and reinsulate them. They will last for years."

Another person says "That corrosion scares the stuffing out of me!"

What is the standard? I would appreciate your assistance VERY MUCH with this....