Cracking and performance of composite tubes and air port designs in a kraft recovery boiler

Cracking of the 304L/SA-210 composite tubes has particularly affected a kraft recovery boiler belonging to one of Paprican's member companies. To evaluate the effectiveness of alternative solutions to this problem, test panels made with several types of composite tubes fabricated into two different port designs were installed in the boiler. These panels have been examined for cracking and corrosion of the cladding/overlay every six months since the time of their installation. The test panel with co-extruded modified A825/carbon steel composite tubes and port design designated "B" was the only one where no cracking or corrosion was found on any of the tubes after 30 months exposure.