Insulated subsea pipe, and materials and methods for applying thermal insulation to subsea pipe
A plurality of concentric plastic tubes are drawn over a steel flowline pipe, with the annuli thus formed between the successive layers of tubing filled with an appropriate insulating material to form a length of pipe suitable for use in a subsea pipeline. The length of steel flowline pipe is at least partially encased lengthwise by a first insulating core of interstitial material. A first length of polymeric tubing is coaxial with the length of steel pipe and radially separates the first insulating core and a second insulating core of interstitial material. A second length of polymeric tubing is radially exterior to the second insulating core, and provides a protective coating for the pipe. Advantageously, the insulated length of pipe may be formed without extruding or molding, and as a result expensive dies and molds are not required.
1 . A insulated length of pipe suitable for subsea operation, said insulated length of pipe comprising:
a metallic flowline;
a first plastic tube co-axial with and drawn over said metallic flowline to form a first annulus between said metallic flowline and said first plastic tube;
a first layer of insulating interstitial material within said first annulus;
a second plastic tube co-axial with said metallic flowline and drawn over said first plastic tube to form a second annulus between said first plastic tube and said second plastic tube; and
a second layer of insulating interstitial material within said first annulus.
2 . The insulated length of pipe of claim 1 , wherein said first layer of insulating material comprises syntactic foam.
3 . The insulated length of pipe of claim 1 , wherein said first layer of insulating material comprises rubber or plastic elastomer.
4 . The insulated length of pipe of claim 1 , wherein said first layer of insulating material comprises asphalt or asphaltic mastics.
5 . The insulated length of pipe of claim 1 , wherein said first layer of insulating material comprises a liquid.
6 . The insulated length of pipe of claim 1 , wherein said first layer of insulating material comprises paraffin wax.
7 . The insulated length of pipe of claim 1 , wherein said first plastic tube comprises polyolefin.
8 . The insulated length of pipe of claim 1 , wherein said first plastic tube comprises polyvinylchloride.
9 . An insulated length of pipe, comprising:
an inner pipe;
a first outer poly sleeve co-axial with said inner pipe;
a first spacer for spacing said inner pipe and said outer poly sleeve to define a first annulus;
a first insulating core within said first annulus that encases lengthwise said inner pipe;
a second outer poly sleeve co-axial with said inner pipe;
a second spacer for spacing said first outer poly sleeve and second outer poly sleeve to define a second annulus; and
a second insulating core within said second annulus that encases lengthwise said first outer poly sleeve.
a first binder that fills interstices in said annulus.
10 . The insulated length of pipe of claim 9 , wherein said first layer of insulating material comprises syntactic foam.
11 . The insulated length of pipe of claim 9 , wherein said first layer of insulating material comprises rubber or plastic elastomer.
12 . The insulated length of pipe of claim 9 , wherein said first layer of insulating material comprises asphalt or asphaltic mastics.
13 . The insulated length of pipe of claim 9 , wherein said first layer of insulating material comprises a liquid.
14 . The insulated length of pipe of claim 9 , wherein said first layer of insulating material comprises paraffin wax.
15 . The insulated length of pipe of claim 11 , wherein said first plastic tube comprises polyolefin.
16 . The insulated length of pipe of claim 11 , wherein said first plastic tube comprises polyvinylchloride.