Pipes for pipelines with heat insulating double casing
AssigneeItp SA
InventorLudovic Villatte
Life of this patent
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Abstract
A line pipe with a double casing is especially used in transporting oil products. In a preferred embodiment, such a pipe is characterized in that, in a sealed annular space, located between an inner tube and an outer tube both coaxially arranged inside each other, there is included a self-sustaining plate made of open pore-microporous material, which is flexible enough to be externally wound around the inner tube. This plate is preferably less in thickness than said annular space such that a passageway is left free between the former and the outer tube whereby low pressure is maintained.
Claims16
A heat-insulating double casing pipe to be especially used in offshore oil pipelines, characterized in that, in an annular sealed space located between an inner tube and an outer tube, both coaxially arranged [in side] inside each other, there is included a self-sustaining plate made of an open-pore microporous insulating material, which is flexible enough to be wound around the inner tube, and in that there is provided outside said microporous insulating material within said annular space, a free passageway to allow longitudinal gas flow, whereby low pressure below 100 millibars is maintained throughout said annular space.
A heat-insulating double casing pipe to be especially used in offshore oil pipelines, characterized in that, in an annular sealed space located between an inner tube and an outer tube, both coaxially arranged inside each other, there is included a self-sustaining plate made of open-pore microporous material, which is flexible enough to be wound around the inner tube, and in that there is provided outside said material within said annular space, a free passageway to allow longitudinal gas flow, whereby low pressure is maintained throughout said annular space;
- characterized further in that the portion of open pores in the material forming said plate is 85 to 95% based on total pore volume, with an average pore diameter less than or equal to 0.1 .mu.m.
A heat-insulating double casing pipe to be especially used in offshore oil pipelines, characterized in that, in an annular sealed space located between an inner tube and an outer tube, both coaxially arranged inside each other, there is included a self-sustaining plate made of open-pore microporous material, which is flexible enough to be wound around the inner tube, and in that there is provided outside said material within said annular space, a free passageway to allow longitudinal gas flow, whereby low pressure is maintained throughout said annular space;
- characterized further in that said microporous material is in the form of ceramic-based insulation plates arranged throughout the pipe;
- characterized further in that said microporous material consists of a mixture containing a major portion of silica together with a minor portion of titanium dioxide;
- characterized further in that the portion of titanium dioxide present in said material is comprised between 30 and 35% by wt. for a silica content of 60 to 70% by wt., based on total weight of the composition thereof.
A method for using a heat-insulating double casino pipe to be especially used in offshore oil pipelines, during service lifetime of a pipeline made from said pipe, comprising the steps of:
- varying pressure generated within an annular sealed space, located between an inner tube and an outer tube, between 50 bars and 1 mbar, in order to vary an outward overall heat transfer coefficient of said pipe in a range of 0.5 W/m.sup.2 .degree. C. to 5 W/m.sup.2 .degree. C.;
- and
- choosing a thickness of a self-sustaining plate made of an open-pore microporous insulating material in the annular sealed space to lie in a range of 10 to 14 mm so as to provide a longitudinal gas flow layer having a mean thickness in a range of 1 to 5 mm.
Dependencies are inferred from the claim text.