|Index & Notes|
Back to "Cluster Rules" chart
Secondly, I looked at when the breaks are clustered in time, but spread out across the whole main. This has been one of the biggest wins for rehabilitation through anode retrofit. When you get a sudden rash of breaks on a main, all over the place, the natural thing to do is panic and replace it. But the time-cluster is probably about a number of holes having already formed, and they all popped at once because of the repairs themselves, cycling the pressure and banging on the main. When you apply anodes at every repair, you may be stopping breaks for several metres on either side, and if you're putting those anodes all along the main, you may we put the fire out, especially if you add a pro-active anode retrofit of the entire length.
Where there's a past time-cluster, and now a new one forming, or I've even found two previous rounds on some old main, twenty years apart, it's certain the anodes are putting out the fire and you just have to do it again.
© Roy Brander, P.Eng 2016