Tightening Sequence for Bolted Flange Joint Assembly

Abstract

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.

Impact of nonlinearity on bolt forces in multi-bolted joints: A case of the assembly stage

“…The tightening procedure was performed in one pass. However, it is possible to carry out this procedure in a few passes, for example following the recommendations given in [33]. Linear characteristics of the springs forming the contact layer are specified by the following function defined on the basis of experimental tests [13]: The calculation results are presented in the graphs shown in Figure 6, in which force variations in the bolts during the pre-tensioning process are presented according to the following scheme: The calculated values of each bolt preload during and at the end of the pre-tensioning process are compared with their experimental values [32].…”

A method to achieve uniform clamp force in a bolted rotor with curvic couplings

“…Elastic interaction of the one-by-one tightening processes can be reduced by multiple tightening passes, which has been discussed Nassar et al 5 and Kumakura and Saito. 10 However, this process increases the preload time and labor intensity greatly. Bolt stress variation during a group tightening process…”

Numerical investigation on the effect of externally exerted loads on particular bolts forces in the multi-bolted flange joint

“…Są one typowe dla struktur, w których przed rozpoczęciem ich eksploatacji wprowadza się napięcie wstępne śrub [3,6,17,31]. Siły w śrubach są przykładane według przyjętej kolejności napinania [9,12,16] oraz założonego sposobu napinania [1,32]. W związku z tym na koniec procesu napinania połączenia siły w poszczególnych śrubach nie są równe.…”