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Hi again,
It depends. In the South, corrosion tends to kill things before fatigue does, so the difference in longevity between swage types will not be as marked. But I have observed that roller swages are more vulnerable to fatigue than rotary, and for two reasons: the rotary machine is much less likely to produce deformations and localized stresses that can lead to fatigue; and in the real world, roller swage machines are far more likely to be out of spec or unskillfully employed than rotaries. The latter point has to do with price; roller swages are much, much cheaper, and tend to end up in the hands of people that don't care as much about quality. Yes, I know that there are riggers out there with Kearney's who are utterly skillful and utterly responsible. But that's not the way to bet. In addition, as I understand it a roller is much easier to knock out of spec, particularly when swaging larger diameters.
In my experience, "12 to 15 years" is more than a little pushing it for rigs in warm climates. Partly this is because I think that crevice corrosion will act faster than that, and partly because it occurs simultaneously with fatigue- and chloride-corrosion, as well as galvanic corrosion. Crevice corrosion on the wire works from the inside out, and the the other three types work from the outside in (though there will also be some crevice corrosion going on in fatigue cracks and chloride pits, as well as the corrosion cracks caused by the expansion of the wire in the terminal).
In the North, fatigue tends to kill rigs before corrosion, though again all the forms tend to work in concert. So in both places the longest-lived rigs tend to be the shiniest, strongest, best-tuned, and appropriately-scantlinged ones that also have their terminals' interiors sealed.
Fair leads,
Brion Toss
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