There are different kinds of pipe defects resulting in metal loss – such as scars, corrosions, pitting, abrasion, grinding off, rupture, puncture or leak, etc. When areas of corrosion or other damage on operating pipelines are identified, there are significant economic and environmental incentives for performing repair without removing the pipeline from service. The paper describes equivalent stress change of the pipe with longitudinal volumetric form defect on pipe surface – approximated as half of ellipsoid. Volumetric surface defect is modeled with three variable parameters. The optimal experiment design is created to analyze the increase in defect. Different thicknesses of applied bandages for each size of the modeled volumetric surface defect are created. The calculation results were collated and it was found that the thicker layer of bandages reduces stress in the repaired area. All results are applicable for further research. The equivalent stress for working pressure is numerically calculated using ANSYS software in the pipes without defect, with defect, and after composite repair with varying thickness of the bandage for different sizes of defect. All results are approximated and analyzed. Optimization methodology is created for the application of composite bandages on the pipelines with volumetric surface defect. Used calculations can be employed for a situation when volumetric surface defect is not parallel to the longitudinal direction of the pipe, as well as to make assumptions about a proper use of safety factors