Abstract: A self-propelled pipe cleaning machine as disclosed for use in removal of deteriorated coatings, such as coal tar or tape, from pipelines and providing a degree of surface preparation suitable for recoating. The machine comprises a travelling frame for motion along the pipe and an oscillating carriage bearing a plurality of counter-rotating cylindrical cutting tools which are urged toward the pipe surface by constant-force pneumatic cylinders. Variation in the pressure of cutters against the pipe surface during oscillation of the cutter head is avoided by counterbalancing of the pivotally-mounted cutters and their associated drive means.

Abstract: In a concrete-wrapped pipe having an inner water-impermeable resinous coating, the concrete wrapping is formed with a continuous inner portion covering the resinous coating and a helically slotted outer portion, the helical slot extending at least to the depth of a mesh reinforcement embedded in the concrete. The structure is characterized by the fact that the inner portion of the concrete wrapping is formed with one or more helically extending zones of reduced compressive strength, radially aligned with the helical slot or slots in the outer portion. The helical configuration breaks the continuityof the concrete wrapping in the longitudinal direction of the pipe and, even with pipe of relatively large diameter, enables the wrapping to accommodate limited bending of the pipe.

Abstract: In a concrete-wrapped pipe having an inner water-impermeable resinous coating, the concrete wrapping is formed with a continuous inner portion covering the resinous coating and a helically slotted outer portion, the helical slot extending at least to the depth of a mesh reinforcement embedded in the concrete. The structure is characterized by the fact that the inner portion of the concrete wrapping is formed with one or more helically extending zones of reduced compressive strength, radially aligned with the helical slot or slots in the outer portion. The helical configuration breaks the continuity of the concrete wrapping in the longitudinal direction of the pipe and, even with pipe of relatively large diameter, enables the wrapping to accommodate limited bending of the pipe.

Abstract: In a concrete-wrapped pipe having an inner water-impermeable resinous coating, the concrete wrapping is formed with a continuous inner portion covering the resinous coating and a helically slotted outer portion forming a helical wrap, the helical slot extending at least to the depth of a mesh reinforcement embedded in the concrete. The concrete wrapping serves as a water-permeable impact resistant barrier while permitting limited bending of the pipe.

Abstract: Cross-linked thermoplastics articles are fabricated by providing a radiant energy-crosslinkable thermoplastics sheet, masking areas of the sheet, exposing the masked sheet to appropriate radiant energy, fusing the masked and relatively uncrosslinked areas together under heat and pressure, and locally applying crosslink inducing energy to the fused portions.

Abstract: A method of thermally insulating pipe comprises rotating the pipe at a uniform speed about a substantially horizontal axis while applying a polyurethane foam mix to the surface of the pipe progressively along its length, simultaneously forming a metal tube of larger diameter than the pipe, the tube being progressively extended coaxially with the pipe and progressively enveloping the newly coated surface of the pipe, and maintaining the pipe at a temperature at which the mix constituents will react to form a foamed mass enveloping the pipe and filling the space between the pipe surface and the tube.