A pipe clamping and alignment tool for locating and clamping pipe sections in accurate end to end alignment for welding has a pair of clamping assemblies for the respective pipe sections threaded respectively on opposite-hand threads of a turnbuckle-type bolt. Each clamping assembly has a cradle for receiving the respective pipe section, a releasable U-bolt clamp for holding the pipe section on the cradle, and pairs of angled adjusting screws for engaging the pipe section and adjusting its alignment both longitudinally and laterally.