As part of the modernization of flue gas ducts, the corroded fasteners or fasteners of unknown material properties (strengths) were found in the existing steel supports during construction work. Therefore, additional diagnostics of bolted connections was carried out in order to identify the condition and strength class of fasteners on the bolted joints of the flue gas ducts supports. If the strength class was different than required by the design documentation, the bolted joint was unmarked (unidentifiable), corroded, damaged, or of inappropriate length, the bolted joint was recorded in the documentation, measured and a new and correct fastener was reported for this joint.
