Annually as baseline; semi-annual on high-pressure systems. The register matters more than the gadget — failures repeat at the same hard-service locations.
From our guide: Steam-trap management — full context, charts and sources there.
Boilers, kilns, heat exchangers, valves and steam lines lose energy continuously. Inzonex makes patented (UK GB2508992.1) removable modular insulation — snap-fastened covers engineered per temperature tier, not generic off-the-shelf jackets: