HIGH TEMPERATURE INSULATED PIPELINES
An insulated high-temperature transport conduit for use in undersea environments. The conduit comprises a continuous steel pipe having at least a first layer of thermal insulation provided over its outer surface. The first layer of thermal insulation comprises a polymer composition having a thermal conductivity of less than about 0.40 W/mK and long-term heat resistance at continuous operating temperatures within the range from about 150° C. to above about 205° C. The first thermal insulation layer comprises a polymer composition comprising a polymer selected from the group consisting of one or more fluoropolymers, hydrogenated nitrile butadiene rubber (HNBR), and a blend of one or more fluoropolymers with HNBR. The conduit may further comprise second and third layers of insulation on top of the first layer, along with a corrosion protection coating underlying the first thermal insulation layer.
1 . An insulated high-temperature transport conduit for use in undersea environments, the conduit comprising:
(a) a continuous steel pipe made up of one or more pipe sections, wherein the steel pipe has an outer surface and an inner surface; and
(b) a first layer of thermal insulation provided over the outer surface of the steel pipe, wherein the first layer of thermal insulation is comprised of a polymer composition having a thermal conductivity of less than about 0.40 W/mK and long-term heat resistance at continuous operating temperatures within the range from about 150° C. to above about 205° C.;
wherein the first thermal insulation layer comprises a polymer composition comprising a polymer selected from the group consisting of one or more fluoropolymers, hydrogenated nitrile butadiene rubber (HNBR), and a blend of one or more fluoropolymers with HNBR.
2 . The insulated transport conduit according to claim 1 , wherein the first thermal insulation layer is a solid or a foam.
3 . The insulated transport conduit according to claim 1 , wherein the first thermal insulation layer is a solid or a syntactic foam.
4 . The insulated high-temperature transport conduit according to claim 1 , wherein the first thermal insulation layer has a thermal conductivity of about 0.15 to about 0.30 W/mK.
5 . The insulated high-temperature transport conduit according to claim 1 , wherein the one or more fluoropolymers comprises a crosslinked, thermoset fluoroelastomer composition.
6 . The insulated high-temperature transport conduit according to claim 5 , wherein the crosslinked, thermoset fluoroelastomer composition comprises a propylene-tetrafluoroethylene copolymer.
7 . The insulated high-temperature transport conduit according to claim 1 , wherein the polymer is crosslinked by a chemical crosslinking agent or by high energy ionizing radiation.
8 . The insulated high-temperature transport conduit according to claim 7 , wherein the polymer is crosslinked by a chemical crosslinking agent.
9 . The insulated high-temperature transport conduit according to claim 8 , wherein the polymer composition further comprises said chemical crosslinking agent.
10 . The insulated high-temperature transport conduit according to claim 9 , wherein said chemical crosslinking agent is a peroxy compound selected from the group comprising monoperoxides, peroxy esters, diperoxides, and combinations thereof.
11 . The insulated high-temperature transport conduit according to claim 9 , wherein the polymer composition further comprises a crosslinking auxiliary agent selected from the group comprising allyl compounds, sulfur, organic amines, maleimides, methacrylates, and divinyl compounds.
12 . The insulated high-temperature transport conduit according to claim 5 , wherein the crosslinked, thermoset fluoroelastomer composition of the first thermal insulation layer is bonded to an adjacent layer by an adhesive which bonds to the fluoroelastomer during vulcanization.
13 . The insulated high-temperature transport conduit according to claim 12 , wherein the adhesive is a liquid adhesive formulated for vulcanization and bonding of elastomers to steel substrates, and comprises a mixture of polymers, organic compounds and mineral fillers dissolved or dispersed in an organic solvent system.
14 . The insulated high-temperature transport conduit according to claim 5 , wherein interlayer adhesion between the crosslinked, thermoset fluoroelastomer composition of the first thermal insulation layer and an adjacent layer is provided by a surface activation pretreatment of the first thermal insulation layer with plasma or corona discharge.
15 . The insulated high-temperature transport conduit according to claim 1 , further comprising a corrosion protection coating directly applied to the outer surface of the steel pipe and bonded thereto, and underlying the first thermal insulation layer.
16 . The insulated high-temperature transport conduit according to claim 15 , wherein the corrosion protection coating is comprised of one or more members of the group comprising an epoxy phenolic, a polyphenylene sulphide, a fluoropolymer, or a polyimide, including modified versions and blends thereof.
17 . The insulated transport conduit according to claim 1 , further comprising an outer protective topcoat applied over the first thermal insulation layer and forming an outer surface of the insulated transport conduit, wherein the outer protective topcoat is comprised of a solid polymeric material.
18 . The insulated transport conduit according to claim 1 , further comprising a second thermal insulation layer on top of the first thermal insulation layer, wherein the second thermal insulation layer is comprised of a thermoplastic in the form of a solid, a blown foam or a syntactic foam.
19 . The insulated transport conduit according to claim 18 , wherein the second thermal insulation layer comprises a polymeric material selected from one or more members of the group comprising: solid or foamed polypropylene homopolymer or copolymer, polybutylene, polyethylene; polystyrene, high impact polystyrene, modified polystyrene, and crosslinked or partially crosslinked polypropylene and polyethylenes, including copolymers, blends and elastomers thereof; and wherein the first thermal insulation layer underlies the second thermal insulation layer.
20 . The insulated transport conduit according to claim 18 , wherein the second thermal insulation layer comprises a polymeric material selected from one or more members of the group comprising: polycarbonate; polyphenylene oxide; polyphenylene oxide blended with polypropylene, polystyrene or polyamide; polycarbonate blended with polybutylene terephthalate, polyethylene terephthalate, acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, or polyetherimide; polyamides, including polyamide 12 and 612 and elastomers thereof; polymethylpentene and blends thereof; cyclic olefin copolymers and blends thereof; and, partially crosslinked thermoplastic elastomers.
21 . The insulated transport conduit according to claim 18 , wherein the second thermal insulation layer comprises an epoxy-modified polymer network.
22 . The insulated transport conduit according to claim 21 , wherein the epoxy-modified polymer network comprises an epoxy-urethane hybrid system or an epoxy-olefin hybrid system having a temperature rating from about 90° C. to about 140° C.
23 . The insulated transport conduit according to claim 18 , wherein the second thermal insulation layer comprises an elastomer selected from the group consisting of HNBR, nitrile butadiene rubber (NBR), silicone rubber, ethylene propylene diene monomer (EPDM) rubber, and butyl rubber.
24 . The insulated transport conduit according to claim 23 , wherein the second thermal insulation layer comprises HNBR.
25 . The insulated high-temperature transport conduit according to claim 5 , wherein the crosslinked, thermoset fluoroelastomer composition comprises a fluoroelastomer selected from Type 1 to Type 5 FKMs, FFKMs, and FVMQs.
26 . The insulated high-temperature transport conduit according to claim 1 , wherein the one or more fluoropolymers comprises a fluorocarbon thermoplastic selected from the group consisting of perfluoroalkoxy (PFA) copolymer of polytetrafluoroethylene and perfluoro alkyl vinyl ether; polytetrafluoroethylene (PTFE); fluorinated ethylene propylene (FEP); a copolymer of tetrafluoroethylene and hexafluoroethylene; and polyvinylidene fluoride (PVDF).
27 . The insulated high-temperature transport conduit according to claim 1 , wherein the one or more fluoropolymers comprises a propylene-tetrafluorethylene copolymer having a mole ratio of tetrafluoroethylene:propylene of from 99:1 to 10:90.
28 . The insulated high-temperature transport conduit according to claim 27 , wherein the propylene-tetrafluorethylene copolymer has a mole ratio of tetrafluoroethylene:propylene of about 55:45.
29 . The insulated high-temperature transport conduit according to claim 27 , wherein the propylene-tetrafluorethylene copolymer further comprises one or more copolymerized components selected from the group consisting of ethylene, isobutylene, acrylic acid, alkyl esters of acrylic acid, methacrylic acid, alkyl esters of methacrylic acid, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, chloroethylvinyl ether, chlorotrifluoroethylene, perfluoroalkylvinyl ether.
30 . The insulated high-temperature transport conduit according to claim 5 , wherein the fluoroelastomer in the crosslinked, thermoset fluoroelastomer composition has a number average molecular weight from about 100,000 to about 250,000.
31 . The insulated transport conduit according to claim 18 , further comprising a layer of adhesive between the first and second thermal insulation layers.
32 . The insulated transport conduit according to claim 18 , further comprising a third thermal insulation layer on top of the second thermal insulation layer, and having a composition which is the same as, or different from, the compositions of the first and second thermal insulation layers.
33 . The insulated transport conduit according to claim 32 , wherein the third thermal insulation layer comprises an epoxy-modified polymer network selected from the group consisting of an epoxy-urethane hybrid system and an epoxy-olefin hybrid system.
34 . The insulated transport conduit according to claim 33 , wherein the second thermal insulation layer comprises an elastomer selected from the group consisting of HNBR and NBR.
35 . The insulated transport conduit according to claim 34 , further comprising a corrosion protection coating directly applied to the outer surface of the steel pipe and bonded thereto, and underlying the first thermal insulation layer;
wherein the corrosion protection coating is comprised of an epoxy phenolic; and
wherein the one or more fluoropolymers of the first insulation layer comprises a crosslinked, thermoset fluoroelastomer composition.
36 . The insulated transport conduit according to claim 34 , further comprising an adhesive layer between the corrosion protection coating and the first thermal insulation layer.