Expanding PIN system – Combined radial and axial locking system

Abstract

In the side by side plate joints or flange joints, the standard practice is to have a bolted connection that provides the axial clamping load as well as, avoiding any radial or rotational movement. This can be problematic since there is not much surface resistance between the bolt and the flanges which can lead to radial motion due to vibrations from heavy loading eventually failure of connection or leakage in high pressured big diameter pipe system. Bondura Technology AS which is known for the out of the box solution for common problems of the industry comes up with a solution for this problem with there ‘bondura® pin system with combined axial and radial locking system’. This pin system is in the initial design phase so, a lot of analyses are required to perform, and this thesis is a contribution to finalize and optimize the product. This thesis is divided into two wide ranges, one part of this thesis is to analyze the different factors goes under consideration for the maximum possible preloads from the bondura® pin system and the relationship between applied torque level and preload as well as, the possible wedge effect from the conical sleeves. And the other major focus of this thesis is the comparison between bondura® pin system and standard bolts in terms of preload capability, loss in preload due to plastic deformation of micro-asperities, and surface resistance between mating surfaces. The preload capability is analyzed theoretically by using the relationship between applied torque and preload since the preload in the bondura® pin system comes from the application of torque to the M10x35 tightening screws. Preload for different levels of applied torque is calculated and an experiment is designed to verify the calculated results which shows promising results with some errors. Also, ANSYS is used to simulate the stress distribution which shows the possibilities of having much more preload since the stress in most of the area is at the lower level of stress. The bondura® pin system does provide much more surface resistance due to high mating surface area but it lacks in terms of preload capability in comparison with standard bolts. The loss in preload due to plastic deformation of micro-asperities is slightly higher for bondura® pin system than standard bolts, due to reliance on the relatively smaller size of tightening screws. While taking different factors under consideration the best possible way to increase the preload of the bondura® pin system is by increasing the size of tightening screws as by using M12 screws the maximum possible preload is increased by 460766.95 N form M10 screws. One of the best possible solutions for overcoming the radial and rotational movement in the flange connection is by using both bondura® pin systems and standard bolts in an optimized manner based on the individual problem as the preload comes from the standard bolts and the surface resistance from bondura® pin system. A mathematical model based on different factors involved in the design of a flange connection can be created, to have an optimized solution.