Welding Residual Stress in HDPE Pipes: Measurement and Numerical Simulation

Abstract

To understand the residual stress distribution in the welded joints of high density polyethylene (HDPE) pipes is essential to the assessment of its structural integrity. However, limited knowledge of their residual stress was available in this regard. In this paper, the hole-drilling strain-gage method was used to measure the residual stress in the welded seam of HDPE pipes, which was produced by the butt fusion welding technique. The finite element modeling using viscoelastic constitutive model with Prony series was carried out to determine the temperature field and corresponding stress field in the welding stages. The measured residual stress near the surface shows good consistency with the numerical results. It is shown that the residual stress in the hoop direction is much larger than those in the radial and axial directions. The effect of the pipe thickness on the residual stress distribution was also investigated by numerical simulation. The positions of the maximum tensile stress in the welded joints were found within the normalized depth region (the radial depth to the thickness) of 0.2 to 0.8.