Test procedures for investigating the buckle propagation of pipe-in-pipe systems

This paper investigates the collapse and propagation of buckling along the length of Pipe-in-Pipe system (PIPs). Experimental study has been performed inside a hyperbaric chamber on buckling of aluminum (Al-6060-T5) PIPs with outer and inner pipe diameter to wall-thickness ratios (D/t) of 30 and 25 respectively. A simple testing method known as Ring Squash Test (RST) is proposed for estimating the propagation buckling pressure of PIPs. Full length hyperbaric chamber and RST results are compared against previously reported empirical equations. It has been shown that the proposed RST is a much expedient test to implement in comparison to hyperbaric chamber test and estimates the propagation pressure of PIPs with reasonable accuracy.