13.5.3 Performance monitoring
The most satisfactory method of detecting tube leaks in steam-to-steam reheaters is by monitoring the live and bled-steam flow rates.
Both live and bled-steam supply lines to the reheaters are therefore usually fitted with flow measuring devices, such as orifice plates or pitot tubes. Tube leaks are identified by a sudden increase in the heating steam flow rate. Thermocouples are sometimes fitted to tubenest headers to ensure that start-up procedures produce acceptable thermal stresses, and thermocouples are also sometimes fitted to reheater tubes to confirm that the tubenest is not subject to unacceptable thermal cycling.