Rigid flange coupling installation method

Rigid flanged couplings require a preload setting prior to installation. However, the pre-tightening force is the artificially pre-applied force before the working load is applied in order to strengthen the reliability and tightness of the connection and prevent the gap or relative displacement between the connectors after the load is applied. Due to the relatively large thermal expansion displacement when the equipment changes in cold and hot states, it may cause excessive stretching of the shaft head diaphragm and eventually lead to material failure, so the diaphragm at the shaft head cannot be used to absorb the displacement, which makes the Setting the coupling nipple preload becomes more important in cold conditions.


Rigid flange couplings are set with appropriate clearance during the cold state, and then the rigid flange coupling sub joints are installed to allow the coupling to stretch and deform in the cold state. In this way, when the unit is running and is in a hot state, the axial displacement caused by thermal expansion will shorten the coupling short joint, thereby offsetting the tensile deformation caused by the application of pre-tightening force, and finally making the coupling in the Work without stress. Without installing the spacer between the pup joint and the shaft head, place the coupling pup joint to the installation position, properly tighten the bolts at the - end, and measure the clearance between the shaft head and the pup joint at the other end. The measured clearance minus the required preload clearance value (there are size requirements in the coupling drawing) is the thickness of the gasket that needs to be added. Usually, the gaskets provided by the manufacturer are a group of gaskets of the same thickness, so as to facilitate on-site adjustment according to the actual situation. After calculating the thickness of the gaskets to be added, the following formula can be used to calculate the number of gaskets to be added: When shims, evenly distribute the shims to be added to both ends of the pup joint. After setting the preload and calculating the number of spacers, you can start installing the coupling nipple.

The bolts at both ends of the short joint in the rigid flange coupling, but if the tightening process is required to strictly follow the torque specified in the drawing and follow the step-by-step and diagonal principles. It is recommended to apply an anti-seize compound to the bolts to avoid thread seizure during installation or removal. Since the shaft head is diaphragm type, it is easy to deform.