EP4257260A1 - POSITION DETECTION DEVICE FOR SEAM PORTION AND HEATED PORTION IN WELDED STEEL PIPE, MANUFACTURING EQUIPPMENT OF WELDED STEEL PIPE, POSITION DETECTION METHOD FOR SEAM PORTION AND HEATED PORTION IN WELDED STEEL PIPE, MANUFACTURING METHOD OF WELDED STEEL PIPE, AND QUALITY CONTROL METHOD FOR WELDED STEEL PIPE | Patent Bear