Pipeline welding positioning tool for ship repairing and building

The invention relates to a pipeline welding positioning tool for ship repairing and building. The pipeline welding positioning tool comprises a base plate and clamping assemblies. The clamping assemblies are divided into a left group and a right group. The base plate is in an arc shape. Supporting blocks are arranged on the left side and the right side of the middle of the inner wall of the base plate in a protruding mode. Each clamping assembly comprises an upper clamping plate and a lower clamping plate. Each upper clamping plate and the corresponding lower clamping plate are each provided with an arc-shaped clamping portion and a horizontal connecting portion. The clamping portions of the lower clamping plates are fixed to the supporting blocks. The connecting portions stretch out of the base plate. A straight rod is vertically fixed to the lower end of the connecting portion of each upper clamping plate. A through hole allowing the corresponding straight rod to penetrate through is formed in the connectin