Method of environmentally protecting a pipeline
First Claim
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1. 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/cm2 ; and
(ii) heating the pipeline or joint to a temperature of at most 40°
C. above the maximum service temperature of the adhesive, said temperature being sufficient to recover the sheet and to activate the adhesive.
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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.
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Citations
18 Claims
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1. 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:
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(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/cm2 ; and (ii) heating the pipeline or joint to a temperature of at most 40°
C. above the maximum service temperature of the adhesive, said temperature being sufficient to recover the sheet and to activate the adhesive. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 17)
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2. 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/cm2 ; - and
(ii) heating the pipeline or joint to a temperature of at most 40°
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. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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18. 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/cm2 ;
- 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°
C. above the maximum service of the adhesive.
- 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°
Specification