Study for Tightening Procedure Using Multiple Tools of Bolted Connections With SWG

Abstract The bolted connections are used in many industries, including power generation, petrochemicals, steel manufacturing, paper manufacturing, semiconductor manufacturing, food manufacturing, airplane, and shipbuilding, and are one of the most important mechanical elements. However, leakage accidents often occurred because of the insufficient gasket contact stress. It is known that the tightening procedure is so important for achievement the sufficient gasket contact stress. Some tightening procedures are studied and suggested in ASME and JIS, but almost of them are for only one tool. The efficiency tightening procedure using multiple tools are required. In this study, the purpose is the evaluation of the tightening procedures using multiple tools for flange connections with gasket. The tightening procedures are evaluated using ASME class 300 12” welding neck flange connections with SWG includes flexible graphite. In experiments, all axial bolt loas of each bolt are measured and monitored using strain gages. Bolt tightening is performed using the hydraulic tensioner. In FEM, the gasket contact stress is calculated.6 suggested tightening procedures for bolted flange connections in ASME PCC-1 Pressure Boundary Bolted Flange Joint Assembly. They are #1-2 Modified star pattern, #3 Circular pattern and Tensioner procedure by using 2 and 4 tools. The axial bolt loads are decreased by the elastic interaction while tightening, so it needs many tightening passes to achieve the high axial bolt loads. However, the gasket contact stress can be obtained easier. It is because the rigidity of the flange in this study is higher. The order of most efficient ways to achieve high gasket stress is tensioner procedure, circular pattern procedure, and star pattern procedure.