Abstract:

To reduce the risk of major safety accidents caused by strength design deficiencies of bimetallic composite pipes in corrosive environments, an X65-316L composite pipe was selected as the research object. A theoretical analytical model and a finite element mechanical model were established based on the plane strain assumption. The mechanical behaviors of single base pipe, equivalent pipe, and composite pipe under different internal pressures (5-30 MPa) were comparatively analyzed. The results show that the bimetallic composite pipe exhibits significantly superior structural performance compared with the base pipe, and its ultimate load-bearing capacity is effectively enhanced. The load is primarily borne by the high-strength base pipe, with the peak von Mises stress located at the base-liner interface, and the liner mainly undertakes the anti-corrosion function. In addition, the equivalent pipe model demonstrates good engineering applicability within the elastic range. Good agreement is achieved between the theoretical predictions and finite element results. The relative errors between the theoretical and finite element results are less than 0.8% for the base pipe model and 14% for the composite pipe model.

Key words: bimetallic composite pipes, internal pressure strength, plane strain assumption, finite element mechanical model, error analysis