A ship’s hull, made of steel, is welded together from individual plates. Welding can cause deformation, a common defect. Predicting this deformation is crucial for shipyard design and management. Numerical analysis using finite elements is widely used for this prediction, with extensive research on the inherent strain-based analysis method. However, determining inherent strain requires synchronizing all strain items over time and considering uncertainties like the welder’s posture and skill. This study derives an integrated inherent strain over the welding process, considering the welding position and cooling method. The derived strain has been implemented and reviewed through numerical analysis of the LNG-powered container ship’s hull assembly process. This integrated inherent strain can serve as a basis for further research on welded structures, materials, welding parameters, and inherent strain-based analysis methods.