We use them all the time at metering stations where pipe comes up from underground and then when it goes back under. it keeps the station pipe isolated from the cathodic protection on the underground pipeline. there are also insulating kits required for the flanges to keep them from re-making continuity through the bolts. wiring is pretty straightforward--one lead from each flange to each of the terminals on the PCR. (-) to the cathodicly protected side and (+) to the grounded side. Then the slightly non-intuitive part--a grounding conductor to the (+) terminal from the grounding grid.
they make both hazardous (Div 2) and non-hazardous version. we generally use the 3.7KV at most stations and the 10KV ones at larger sites.
Never had one fail (or even been told that one failed) in the 5+ years I've been doing this, so can't say much about their lifespan.
Hope that helps.
