Understanding and Addressing Radially-Inward Buckling (RIB) In Spiral-Wound Gaskets (SWG)
Radially-inward buckling, or RIB, is a phenomena noted in spiral-wound gaskets (SWG) since the mid-1980s, defined by a mechanical rupture in the continuity of the inner SWG winding material forming the gasket. This rupture may or may not result in gasket failure as evidenced by a leakage event. In severe cases, the rupture can result in a sizeable catastrophic local buckling characterized by separation of the metal windings, afterwhich the windings have become entrained in the process fluid flow thereby affecting downstream system components by plugging filters, damaging valve seats, and fretting of heat exchanger tubing. In all severe cases, whether external leakage occurs or not, RIB results in degradation of the design pressure boundary for that seal.
This technical brief traces the history of RIB events from 1985-2005 and compiles and analyzes available historical information on RIB events from the Chemical, Refining, and Power Generation industries. The Brief also includes an analysis of information generated by the Electric Power Research Institute (EPRI), the Fluid Sealing Association (FSA), and the Pressure Vessel Research Council (PVRC) on the topic for the same period. The Tech Brief examines the traditional explanations for the occurrence of RIB events and provides a definitive explanation of the root cause and principal contributory factors consistent with research results and field experience. The document concludes with recommendations to mitigate RIB and susceptability of various gasket types.