We never really considered our HRSG a "fired heater", even though we did have duct burners for supplemental heating. They were on most of the time but we could still produce steam without them. That said, it wouldn't hurt to include a HRSG in a fired heater program if your site has one, depending on budget. For us being a refinery, HRSG tubes were the least of our concerns for failure because the consequence of failure was much lower than a fired process heater. I had to do some convincing to get preemptive inspections done on our tubes.