Method of environmentally protecting a pipeline
AssigneeRaychem Corporation
InventorsNoel M. M. Overbergh, Yvo Leest
Life of this patent
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Abstract
A method of covering a joint between pipelines comprises installing a heat recoverable polymer sheet coated on its inner surface with a hot-melt adhesive comprising a mixture of 25 to 40 parts by weight of a polyethylene alkyl acrylate terpolymer containing maleic anhydride and having a melt flow index as determined according to ASTM D1238-70 of at least 40, and 25 to 70 parts by weight of a polyethylene alkyl acrylate copolymer having a melt flow index as determined according to ASTM D1238-70 of at least 40.
Claims18
A method of environmentally protecting a polymer-coated metal pipeline, or a joint between two such pipelines where the pipelines have been bared of polymer coating at the joint region, the method comprising:
- (i) positioning a heat recoverable sheet which is coated on one surface thereof with a hot melt adhesive composition, such that the adhesive faces the pipeline, and such that the adhesive-coated sheet at least overlaps the polymer coating, the adhesive (a) comprising a mixture of 25 to 40 parts by weight of a polyethylene alkyl acrylate terpolymer containing maleic anhydride and having a melt flow index as determined according to ASTM D1238-70 of at least 40, and 25 to 70 parts by weight of a polyethylene alkyl acrylate copolymer having a melt flow index as determined according to ASTM D1238-70 of at least 40, and (b) having a maximum service temperature at which the adhesive maintains a bond to a substrate and shows no movement when subjected to a static shear creep force of 2.50 to 2.75 N/cm.sup.2 ;
- and
- (ii) heating the pipeline or joint to a temperature of at most 40.degree. C. above the maximum service temperature of the adhesive, said temperature being sufficient to recover the sheet and to activate the adhesive.
A method of covering a bare metal pipeline, a polymer coated pipeline, or a joint between such pipelines where the pipelines have been bared of insulation in the joint region, the method comprising
- (i) helically wrapping a heat recoverable tape around the pipeline or insulation, the tape being coated on the inward facing surface with an adhesive which (a) comprises a mixture of 25 to 40 parts by weight of a polyethylene alkyl acrylate terpolymer containing maleic anhydride and having a melt flow index as determined according to ASTM D1238-70 of at least 40, and 25 to 70 parts by weight of a polyethylene alkyl acrylate copolymer having a melt flow index as determined according to ASTM D1238-70 of at least 40, and (b) has a maximum service temperature at which the adhesive maintains a bond to a substrate and shows no movement when subjected to a static shear creep force of 2.50 to 2.75 N/cm.sup.2 ;
- and
- (ii) heating the pipeline or joint to a temperature of at most 40.degree. C. above the maximum service temperature of the adhesive, said temperature being sufficient to recover the tape into close conformity with the pipeline, and to activate the adhesive.
A pipeline or joint between pipelines having a heat recovered sheet or helically wrapped tape adhered thereto by an adhesive (1) comprising a mixture of (i) 25 to 40 parts by weight of a polyethylene alkyl acrylate terpolymer containing maleic anhydride and having a melt flow index as determined according to ASTM D1238-70 of at least 40, and (ii) 25 to 70 parts by weight of a polyethylene alkyl acrylate copolymer having a melt flow index as determined according to ASTM D1238-70 of at least 40, and (2) having a maximum service temperature at which the adhesive maintains a bond to a substrate and shows no movement when subjected to a static shear creep force of 2.50 to 2.75 N/cm.sup.2 ;
- wherein the sheet or tape was recovered and the adhesive was activated to bond it to the pipeline by heating the pipeline or joint to a temperature of at most 40.degree. C. above the maximum service of the adhesive.
Dependencies are inferred from the claim text.