Insulated pipe and method for preparing same

Abstract

The invention provides an insulated pipe-in-pipe assembly comprising (a) at least one inner pipe, (b) an outer pipe disposed around the at least one inner pipe so as to create an annular space between the outer and inner pipes, (c) porous, resilient, compressible material disposed in the annular space, and (d) a remnant of a container that previously was positioned in the annular space and previously held the compressible material in a volume less than the volume of the compressible material in the annular space. The invention also provides a method for making such an insulated pipe-in-pipe assembly.

Description

PRIOR APPLICATIONS [0001] This application claims the priority of U.S. Provisional Application 60 / 687,672 filed on Jun. 6, 2005.FIELD OF THE INVENTION [0002] This invention pertains to a thermally insulated pipe-in-pipe assembly and a method of preparing the same. BACKGROUND OF THE INVENTION [0003] In deep-water hydrocarbon (e.g. oil, gas or mixtures thereof) extraction, crude oil or gas is extracted from below the sea floor and transferred via a pipeline system to the surface of the water. It is critically important to maintain the temperature of the oil or gas flowing through the pipeline, which typically is extracted at elevated temperatures (e.g., 60-300° C.), at temperatures above about 40° C. to avoid the precipitation of solid materials and hydrates which can lead to plugging of the pipeline and interfere with production. As the water temperature at great depths is slightly above freezing temperature (e.g, about 4° C.), provision must be made to insulate the pipelines. Furthe...

AI Technical Summary

Problems solved by technology

However, existing methods of insulating pipe-in-pipe assemblies remain deficient in numerous respects.

Pre-formed insulating panels and the like, of necessity retain gaps in insulation when placed within pipe-in-pipe assemblies, both between their opposing edges and between ends when laid end-to-end, allowing for heat transfer between inner and outer pipes, which reduces insulation efficiency and requires greater amounts of insulating materials.

Maintenance of reduced pressure within the annular space of some pipe-in-pipe assemblies places great demands on forming vacuum-tight assemblies and places the performance of the assembly at risk should the vacuum be compromised.

Some insulating materials such as polyurethane foam lose insulation efficiency and / or shape over service life.

Other insulating materials require the use of a larger diameter outer pipe to accommodate sufficient insulating material due to less efficient insulation capabilities.

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