Tightening Sequence for Bolted Flange Joint Assembly

Bolted flange joint assembly has been widely used in chemical and nuclear plants. Insufficient bolt loads in the bolted flange joints lead to serious accidents. The insufficient bolt loads are due to inappropriate bolt tightening methods in many cases. In order to obtain target bolt loads by the torque control method, it is especially important to know a torque coefficient and an appropriate tightening sequence. Another problem exists because where mating flanges are tightened by multiple bolts. It is known that it is extremely difficult to obtain a uniform bolt loads among the multiple bolts. In this study, new and any experimentally examined, tightening sequences for the bolted flange joints using multiple bolts are proposed. As a result, the proposed tightening method was proved to be more effective than that by the ASME method.