Effect of welding axial stresses on the strength of a welded pipe joint with a defect

The use of an integrated approach to determining the static strength of operated main pipelines with surface defects makes it possible to take into account the effect of residual weld stresses in combination with operational loads. In this case, it is important to determine the nature of the welding stress distribution for welded structures made of high-strength steels. Here, there is non-uniformity of stresses concerning magnitude and gradient, which is due to technological methods. A mathematical model of the experimental-calculation method is proposed. Such a model allows describing such stresses. A two-parameter criterion for brittle-tough fracture of a material which takes into account the influence of residual stresses is used. It is shown that the combination of residual stresses and operating loads has a significant effect on the safety factor. At the same time, conditions are possible under which compressive residual stresses have a favourable effect on the static strength of a pipeline with a defect.