Experimental Investigation on Buckling of Plastic Pipe Reinforced by Winding Steel Wires Under External Pressure

Abstract

Plastic pipe reinforced by cross helically wound steel wires (PSP) is a new type of plastic-matrix steel composite pipes developed in China recently. PSPs may collapse when they are subjected to an external pressure load. To obtain the buckling behavior of PSPs and provide basic data for Chinese National Standard of PSPs, the testing devices of external hydraulic pressure and vacuum were designed for short-term buckling and creep buckling tests, and corresponding tests had been carried out. The critical buckling pressure, the methods to increase the critical buckling pressure, the relationship between creep deformation and time under different pressures, and the variation of the critical buckling time with critical creep buckling pressures of the PSP were obtained. The results show that the short-term critical buckling pressure of the PSP is higher than that of the HDPE with the same diameter and wall thickness. The critical buckling pressure of the PSP with the same pressure class decreases gradually with the increase of pipe diameter. The resistance to buckling can be increased by installing stiffening rings on the PSP. Furthermore, the PSP shows time-dependent buckling behavior, because of the time-dependent behavior of the matrix. Even if the external pressure load is lower than the short-term critical buckling pressure of the PSP, the buckling failure may still occur, and the time of buckling failure gradually shortens with the increase in the external pressure.