Pulp and Paper Processing Equipment
A felt guide roll fractured in-service on a paper manufacturing machine, damaging the belt as well as multiple dryer rolls, nearby felt guide rolls, and the frame of the machine. The investigation included visual and stereoscopic examination, chemical and microstructural analysis, microhardness and tensile testing, stress calculations, and vibration measurements. Based on the results, the roll fracture was attributed to high-cycle fatigue associated with a plug weld over one of the five threaded fasteners added to secure a balance weight inside the roll. The balance weight was installed to compensate for variations in wall thickness (i.e., weight distribution) of the pipe product used to make the roll. According to the investigation, resonance and vibration, which were initially considered, did not cause the failure.