High temperature field joints

An insulated conduit, comprising:

• (a) a first insulated pipe section and a second insulated pipe section, wherein each of the insulated pipe sections comprises:
• (i) a steel pipe having an outer surface and an end, wherein an annular connection surface is located at said end of the steel pipe,
• (ii) a corrosion protection coating provided over the outer surface of the steel pipe, wherein a terminal end of the corrosion protection coating is spaced from the end of the pipe;
• (iii) a pipe insulation layer provided over the corrosion protection coating, wherein a terminal end of the pipe insulation layer is spaced from the end of the pipe, and wherein the pipe insulation layer comprises a polymer composition having thermal conductivity of less than about 0.40 W/mk, and/or heat resistance to continuous operating temperatures from about 150° C. to above about 205° C., wherein the corrosion protection coating and the pipe insulation layer together comprise a line pipe coating of the insulated pipe sections;
• and
• (iv) a circumferential weld joint between the annular connection surfaces of the steel pipes, wherein a continuous joint area includes the circumferential weld joint and the bare end portions of the insulated pipe sections;
• (b) a field joint comprising:
• a first field joint insulation layer over the joint area, wherein the first field joint insulation layer is a propylene-tetrafluoroethylene copolymer crosslinked with an allyl compound, and optionally additives, and wherein the first joint insulation layer has a heat resistance to continuous operating temperatures from about 150° C. to above about 205° C.;
• wherein the optional additives first field joint insulation layer are selected from one or more members of the group of inorganic fillers, reinforcing fillers or fibres, nano-fillers, conductive fillers, flame-retardant fillers, antioxidants, heat-stabilisers, process aids, compatibilisers, organic fillers, and pigments.

An insulated conduit, comprising:

• (a) a first insulated pipe section and a second insulated pipe section, wherein each of the insulated pipe sections comprises:
• (i) a steel pipe having an outer surface and an end, wherein an annular connection surface is located at said end of the steel pipe,
• (ii) a corrosion protection coating provided over the outer surface of the steel pipe, wherein a terminal end of the corrosion protection coating is spaced from the end of the pipe;
• (iii) a pipe insulation layer provided over the corrosion protection coating, with the line pipe layer comprising a layer of a crosslinked fluoroelastomer composition and a layer of that is different from the crosslinked fluoroelastomer composition, wherein a terminal end of the pipe insulation layer is spaced from the end of the pipe, and wherein the pipe insulation layer comprises a polymer composition having thermal conductivity of less than about 0.40 W/mk, and/or heat resistance to continuous operating temperatures from about 150° C. to above about 205° C., wherein the corrosion protection coating and the pipe insulation layer together comprise a line pipe coating of the insulated pipe sections;
• and
• (iv) a circumferential weld joint between the annular connection surfaces of the steel pipes, wherein a continuous joint area includes the circumferential weld joint and the bare end portions of the insulated pipe sections;
• (b) a field joint comprising:
• (i) an anti-corrosion coating over the joint area and in contact with the bare end portions, wherein the anti-corrosion coating comprises a silicone elastomer having heat resistance to continuous operating temperatures from about 150° C. to above about 205°C.;
• (ii) a first field joint insulation layer directly over and in contact with the anti-corrosion coating over the joint area, wherein the first field joint insulation layer is a propylene-tetrafluoroethylene copolymer crosslinked with an allyl compound, and optionally additives, and wherein the first joint insulation layer has a heat resistance to continuous operating temperatures from about 150° C. to above about 205° C.;
• wherein the optional additives first field joint insulation layer are selected from one or more members of the group of inorganic fillers, reinforcing fillers or fibres, nano-fillers, conductive fillers, flame-retardant fillers, antioxidants, heat-stabilisers, process aids, compatibilisers, organic fillers, and pigments;
• and
• (iii) a second field joint insulation layer directly over and in contact with the first field joint insulation layer, wherein the second field joint insulation layer comprises a polymer composition having heat resistance at continuous operating temperatures in a range from about 90° C. to above about 140° C. and comprises an epoxy-modified polymer network;
• wherein the first and second field joint insulation layers have a combined thickness which is greater than that of the line pipe coating, and wherein the second field joint insulation layer overlaps the line pipe coating on both sides of the joint area.