The Effect of Pipe Thickness on Residual Stresses due to Girth Welds

Abstract

This paper addresses the question of what effect the pipe thickness has on weld residual stresses in 304 stainless steel piping. Two diameters are considered. These are nominal 4-in. and 10-in. diameters. Four pipe wall thicknesses corresponding to schedules 10, 40, 80, and 160 are examined for each pipe. The focus is on residual stress distributions on the pipe inner surface because this is a primary site for intergranular stress corrosion cracking in 304 stainless steel pipes. The trends in residual stress values are toward more compressive stresses at the pipe inner surface for thicker pipes with the same nominal diameter. Residual axial stresses for the thick 10-in. schedule 160 pipe were found to be compressive while those for the thinner schedule 80 pipe were tensile. X-ray residual stress data for a 6-in-dia schedule 160 pipe fall between the results for the 4-in. and 10-in. schedule 160 pipes and support the findings of the study.

Analysis of weld-induced residual stresses and distortions in thin-walled cylinders

“…Similar trends for stress reduction and stress reversal are observed for hoop residual stresses as for axial residual stresses. The trend for the hoop stress also agreed well with the previous research [5,8,10,12,13]. The quantitative variation is again attributed to different welding parameters, heat source parameters and material properties in the present and referred research work, respectively.…”

“…The general residual axial stress profile shows close analogy with the previous research [5,8,10,12,13]. The variation in magnitude (higher or lower residual stresses) in the present research work is attributed to the different material properties, i.e., mechanical properties like yield strength for base and weld filler metals along with other parameters such as weld geometry and heat source parameters.…”

“…A significant simulation and experimental work focusing on circumferential welding is available in the literature [4][5][6][7][8][9][10][11]. As the computer simulation of welding processes is highly computationally intensive and large computer storage and CPU time are required, most of the previous research reduces computational power requirements by simplifying with assumptions such as rotational symmetry and lateral symmetry in numerical simulations [5][6][7][8]. These assumptions reduces the computational demand at the cost of the accuracy of the results because the model was over simplified by limiting the solution domain to only a section of the whole domain with forced symmetry assumptions which did not prevails.…”

“…However, with the availability of 64 digit computers and refined FE tools, welding engineers around the world are more biased towards the computer simulations of complex welding phenomenon instead of the conventional trial and error approach on the shop floor. A significant simulation and experimental work focusing on circumferential welding is available in the literature [4][5][6][7][8][9][10][11]. As the computer simulation of welding processes is highly computationally intensive and large computer storage and CPU time are required, most of the previous research reduces computational power requirements by simplifying with assumptions such as rotational symmetry and lateral symmetry in numerical simulations [5][6][7][8].…”

Prediction of residual stresses in gas arc welding by back propagation neural network

“…Among them, Rybicki et al studied the effect of wall thickness and pipe diameter by using asymmetric FEA model with lateral symmetry in multi-pass welding of stainless steel pipes [9]. Dong et al used a shell model with lateral symmetry to investigate the effect of pipe wall thickness and welding speed for thin as well as thick walled pipes [3].…”