Line Up Clamps Adapted to Be Positioned Inside Abutting Ends of Two Pipe Sections which Are to Be Welded and which Clamps Are Adapted to Be Expanded Outwardly to Hold the Ends of the Abutted Pipes in Alignment, Pipe Cradles of the Type which Are Supported by a Crane and which Encircle a Pipe Section with Rollers Engaging the Bottom of the Pipe for Supporting the Pipe While Permitting Travel of the Cradle Along the Length of the Pipe, Pipe Slings of the Type in which Bands of Woven Nylon Webbing Are Adapted to Be Looped Around the Pipe Section and Are Coupled to a Fixture onto which a Cable May Be Connected for Supporting the Pipe Section Through the Sling, Welding Machines, [ Track Wheels of the Type in which Continuous Treads Encircle Horizontally Spaced Apart Guide Wheels and which May Be Utilized on a Variety of Vehicles as a Tracked Roller Assembly, ] Marine Pipeline Laying Pipe Conveying Units Wherein Rollers Mounted on a Frame to Be Supported on the Barge Permit Ready Movement of the Pipe in the Direction of the Pipe Axis Where the Rollers Are Mounted to Form a V-Shaped Conveyer