Experimental and numerical investigation of barreling at the cut ends of solid and skinned PE pipes

When a thermoplastic pipe is cut to length, residual stresses frozen in during cooling are released, causing local bending which reduced the diameter of the pipe at the cut end. Moving back inwards from the cut end, the measured pipe diameter does not simply increase to its initial value but locally overshoots to a new maximum, giving the end of the pipe a 'barrel' shape that can be inconvenient in electrofusion joints. This paper investigates the development of barreling in solid and skinned PE pipes in terms of these frozen in stresses. Residual stresses are predicted using a thermoelastic model and compared with experimental data obtained using the layer removal method. A shell-theory solution for barreling is coupled to the numerical analysis to determine the deflection of the pipe wall near the cut end. Barreling is simulated for PE pipe of various dimensions and processing conditions. The model is validated with experimental data and the effect of barreling on electrofusion joints is discussed in terms of common procedures and standards.