A boiler wall tube tool comprises a pair of opposed clamp members, each one of the clamp members having a nose intermediately disposed between a recess and a planar or inclined wall, and an aperture formed centrally through the clamp member. The clamp members oriented so that the recess of one of the clamp members is substantially aligned with the planar wall of the remaining clamp member for engaging a boiler wall tube therebetween. The aperture of one clamp member is substantially aligned with the aperture of the remaining clamp member. Means for moving the clamp members toward each other for secure clamping engagement of the tubes for maintaining the clamp members in alignment while connecting the ends of the tubes by welding is also provided.