Recently, drilling holes in petroleum transmission pipelines is becoming of major concern for pipeline companies. These drilled pipelines must be repaired through welding ways. There are two ways to repair these pipelines in fields. One is welding a short tube with a cap. Another is welding a patch. In this paper, full scale experiments were conducted to assess the stresses state and the loading capability of the repaired pipelines. The φ711×10 pipelines repaired by welding a tube cap or a patch were pressured to burst failure. Strain gages have been used extensively to monitor stress state in full scale pipeline tests. It was showed that welding a tube cap or a patch resulted in the non-uniform stresses distribution and the stress concentration in the extent. These two kinds of the repaired pipeline has almost the similar yield limit pressure which are approximately equal to 85% of that of pipelines that were not damaged. Patching repair has more restriction to the deformation around a hole than tube capping repair, therefore it may have a little better loading capacity than tube capping repair. The burst pressures in these tests are close to that of pipeline which has not been damaged, whereas the location of burst failure is far from where a short tube or a patch is welded. The burst is a ductile fracture by maximum shear stress.

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