Your heat tracing has monitoring so that operators get an alarm if a break occurs. Last week, an outdoor storage tank lost heat tracing on its overfill line. A couple of days later, it lost heat tracing on its fill line. Yesterday, it lost heat tracing on its drain line. Today, the overfill line heat tracing failed again. In each case, the heat tracing was broken.
Techs prevented freeze-ups by making splices promptly. The shift supervisor remarked, “As extremely cold as it's been, we're lucky they fixed the heat tracing in time to prevent lines from freezing.”
How can you track down the cause(s) of these failures, and could they be related?
It's good that the repair techs are fast. But are they perhaps too fast? Notice the order in which the failures occurred.
The overfill line, high up, failed. That can happen. But then the ones below it failed. Perhaps in their haste, the techs climbed on the piping instead of getting a ladder? Does this really seem just coincidental?
Might there be some other shortcuts the techs took? For example:
Perhaps humans caused the first breakage. Even if the area is secured against intrusion by vandals, company personnel might inadvertently be causing damage (or deliberately sabotaging). Just because you don't see evidence of “people presence” (e.g., footprints, cigarette butts, food wrappers) doesn't mean people aren't causing these problems. If the problems persist, a security camera with motion detector control might be a good investment.