  After a bolted gasketed pipe flange connection is finished assembling, the pipe flange connection is usually subjected to some additional loads such as bending moment, own weight of the connection, wind load and so on. These additional loads lead to change the axial bolt force distributions in the pipe flange connections and the distributions would become more and more scattered. As a result, the minimum residual axial bolt force will be much smaller and the minimum contact gasket stress will decrease. So a leakage is easy to occur in the connection. In special, when earthquake occurs, the bolted pipe flange connection is usually subjected to a high bending moment. Then sometimes leakage accidents occur. In order to promote the safety of the connections and to avoid them being broken under the earthquake, some researches on the pipe flange connections under bending moment have been performed. In some researches, the effect of the bending moment which is applied to the connection on a leak rate of the connection and an equivalent pressure is defined from the bending moment. In addition, an assembly efficiency of the connection is used in designing bolted flange connection with gaskets based on a ratio of actual total axial bolt forces to the target axial bolt forces in the connection. Recently, the assembly efficiency which is obtained based on the leak rate. But there are only a few researches focused on the equivalent pressure and assembly efficiency to redesign the pipe flange connection under bending moment. In the present paper, the equivalent pressure and the assembly efficiency in the pipe flange connection of class 150 4” are measured experimentally. The leak rates of the connection used spiral-wound gasket when a bending moment was applied or not applied were measured to elicit the equivalent pressure. Moreover, some tightening procedures such as JIS B 2251 and ASME PCC-1 Legacy were applied to tighten the pipe flange connection. The axial bolt force, the bolt force distribution, the assembly efficiency based on the achievement of target axial bolt force and the assembly efficiency based on tightness parameter of the pipe flange connection when bending moment was applied or not applied were measured and the measured results are compared. As a result, the equivalent pressure under a given bending moment is obtained. In addition, the new assembly efficiency based on tightness parameter is also measured under a given bending moment as well as internal pressure. Using the equivalent pressure and the assembly efficiency obtained in the present paper, a new design will be possible for the pipe flange connections under bending moment.


Experimental Study on the Characteristics of Bolted Pipe Flange Connection Under Bending Moment and Internal Pressure

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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