Flexible unbonded pipe and a method for producing such pipe
The present invention relates to a flexible unbonded pipe comprising an inner liner capable of forming a barrier against outflow of a fluid which is conveyed through the pipe, and one or more armouring layers on the outer side of the inner liner. The flexible unbonded pipe comprises at least one polymer layer and at least one film layer, the polymer layer being bonded to the film layer via one or more bondings selected from the group of chemical bondings and physical bondings. The film layer may preferably be a metal film layer. The polymer layer may preferably be cross-linked polyethylene. The interfacial bonding between the polymer layer and the film layer should preferably be sufficiently strong to prevent creation of gas pockets between the layers when subjected to an increased pressure of aggressive fluids on the film side of the pipe.
1. A flexible unbonded pipe, said pipe comprising at least one polymer layer, at least one film layer, and one or more armouring layers, said film layer being a metal film layer and said polymer layer being at least 4 mm thick and being bonded to said film layer via one or more bondings selected from the group of chemical bondings and physical bondings,
wherein said armouring layers are not bonded to neither said polymer layer nor said film layer, and said armouring layers are not bonded to each other, and
wherein said film layer and said polymer layer are of different materials.
2. A flexible unbonded pipe according to claim 1 , wherein the bonding between the polymer layer and the film layer has a peel strength using ASTM D3330 of at least 300 N/m.
3. A flexible unbonded pipe, said pipe comprising at least one polymer layer, at least one film layer, and one or more armouring layers, said polymer layer being bonded to said film layer via one or more chemical bondings, and the interfacial bonding between the polymer layer and the film layer being sufficiently strong to prevent creation of gas pockets between the layers when subjected to an increased carbon dioxide pressure of 5 bar on the film side of the pipe,
wherein said armouring layers are not bonded to neither said polymer layer nor said film layer, and said armouring layers are not bonded to each other, and
wherein said film layer and said polymer layer are of different materials.
4. A flexible unbonded pipe, said pipe comprising at least one polymer layer, at least one film layer, and one or more armouring layers, said polymer layer being at least 4 times thicker than said film layer, said film layer being a wounded or folded film layer, and said polymer layer being bonded to said film layer via one or more bondings selected from the group of chemical bondings and physical bondings,
wherein said armouring layers are not bonded to neither said polymer layer nor said film layer, and said armouring layers are not bonded to each other, and
wherein said film layer and said polymer layer are of different materials.
5. A flexible unbonded pipe, said pipe comprising at least one polymer layer, at least one film layer, and one or more armouring layers, said polymer layer being a cross-linked polyethylene and said polymer layer being bonded to said film layer via one or more chemical bondings, and said bondings being established by the cross-linking of the polyethylene,
wherein said armouring layers are not bonded to neither said polymer layer nor said film layer, and said armouring layers are not bonded to each other, and
wherein said film layer and said polymer layer are of different materials.