Experimental Determination of the Propagation Pressure of Circular Pipes

Local geometric imperfections on pipes under external pressure can lead to local buckling which under the “right” conditions can cause the initiation of a propagating buckle. This buckle, driven by the pressure, propagates up and down the pipe flattening it. The lowest pressure which can sustain a propagating buckle is called the propagation pressure and is a characteristic pressure of the pipe. Experiments have shown this pressure to be dependent on the post yield characteristics of the pipe material behavior, as well as the diameter-to-thickness ratio of the pipe. The collapse mechanism has been modeled by the collapse of a ring under external pressure. By identifying the lowest postbuckling pressure of the ring with the propagation pressure an empirical expression for the latter quantity has been established.