Abstract: An external pipe covering apparatus is provided for coating exterior surfaces of uncoated longitudinal, helical and girth weld joints of a pipe to provide protection against corrosion, to minimize the weld projection by filling in any voids on either side of a weld, and to further provide a uniform smooth surface for a later applied tape. The apparatus is moved along a pipe by a crane or similar mechanical device. The apparatus has a carriage to which is attached wheels, a reservoir attached to the upper frame of the carriage for holding liquid resin, a circular member having at least one sensor therein attached to the lower frame of the carriage, a microprocessor attached to the upper frame of the carriage, a circular dispenser for dispensing liquid resin having at least one nozzle and at least one solenoid valve attached to the lower frame of the carriage for dispensing resin from the reservoir, and a pump for delivery of liquid resin to the nozzle.

Abstract: Method for heating a heat-shrinkable pipewrap wherein the heat for shrinking is applied simultaneously throughout the periphery of the pipewrap surface; and novel apparatus useful therefor.

Abstract: Pipe coating having a thermal insulating layer of polymeric material and an outer barrier layer is provided with an additional layer between the two layers to facilitate testing of the latter for discontinuities. The intermediate layer can be electroconductive, smooth-surfaced, or of color contrasting to that of the barrier layer.

Abstract: Pipe coating having a thermal insulating layer of polymeric material and an outer barrier layer is provided with an additional electro-conductive layer intermediate between the two layers to facilitate testing of the latter for discontinuities by conventional electric testing equipment for detecting discontinuities in the outer barrier layer, e.g. by measuring electrical conductivity or resistivity along the face of the barrier layer.

Abstract: In a pipe coating made by wrapping the pipe with polyolefin tape and a butyl rubber based adhesive, the strength of the bond to the pipe at elevated temperature is improved by incorporating in the adhesive a cross-linking agent which is either 0.15-1% by weight of p-dinitrosobenzene or 1.0 to 2.5% of p-quinonedioxime, or both together with an activator.

Abstract: Steel pipe is provided with an external protective coating by first applying a corrosion protective coating of fused powdered epoxy resin adhered to the pipe, then applying (e.g. as by wrapping a sheet) an outer polyolefin layer directly onto the corrosion protective coating. The outer sheet of polyolefin is provided with a pressure-sensitive adhesive or a hot melt adhesive which adhesive may also be reactive with the epoxy coating (e.g. one having free carboxyl group such as ethylene acrylic acid copolymer). The polyolefin is preferably polyethylene or polypropylene and most preferably polyethylene. Either high or low density polyolefin may be used.