Inspections of superheater headers should be conducted in a manner similar to that for waterwall headers. Usually, not all superheater handholes are opened at every boiler shutdown or cleanout unless tubes are to be replaced or other repairs are to be made. However, a few should be removed at every shutdown as a spot check. If the unit cycles frequently, some of the ligaments between tubes should be examined for cracking with either UT or WFMT, depending on access.
Since only dry steam passes through the superheater, there should be few or no deposits present in the headers or tubes. If deposits or scale are present in any degree, immediate steps should be taken to determine why they are present. In addition, the extent of the deposits or scale should be investigated. Superheater tubes with a moderate deposit of scale will rupture readily from effects of overheating. Indications of scale or deposits should lead to an investigation of the steam separators, dry box, operating drum level and fluctuations, blowdown rates, and water quality.