Insulated pipe joint

Abstract

A pipeline (20) that lies primarily in the sea and that consists of multiple steel pipe sections connected in tandem at pipe joints, includes a protective coating around the pipe sections and around the pipe joints. Each pipe section is first covered, at an onshore facility, by an initial coating (30, 32) that extends along at least 80% of the pipe section length while leaving its ends uncovered, to leave gripping areas (40, 42) where the steel of the pipe is uncovered so the pipe can be clamped by tools such as those with steel jaws to position and slide it axially, or turn it, or prevent it from turning. After a pair of pipe sections are connected, a completion coating (50) is applied around the pipe joint to leave the pipeline with a coating around all of it.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of an installation vessel and of a steel pipeline being installed by the vessel into the sea.

FIG. 2 is a partial sectional view of two pipe sections that are joined in a pipe joint, with each pipe section having an initial coating that leaves bare steel gripping surfaces at the end portion of the pipe section.

FIG. 3 is a partial sectional view of the two pipe sections of FIG. 2, with a completion coating lying around the pipe joint and around ends of the initial coatings

FIG. 4 is a partial sectional view of two joined pipe sections, showing a completion coating being applied by overmolding.

FIG. 5 is a partial sectional view of two joined pipes with a completion coating applied, where the pipe sections have enlarged ends.

Claims

1. A method for connecting together adjacent first and second pipe section ends of first and second pipe sections to form a pipe joint, while the pipe sections are supported on an installation structure that lies in a sea, and to provide a covering around said pipe sections that extends continuously along the length of said first and second pipe sections including said pipe joint, during the installation of a string of multiple tandem-connected pipe sections in the sea, comprising: prior to connecting said ends of said pipe sections, covering each of said first and second pipe sections with an initial covering that extends along at least 80% but less than the entire length of the corresponding pipe section, while leaving an uncovered gripping surface extending a plurality of centimeters away from each of said first and second pipe section;connecting said first and second pipe section ends to form said pipe joint, including engaging both pipe sections by gripping tools at their uncovered gripping surfaces;after connecting said pipe section ends to form said pipe joint, applying a completion covering around an exposed joint surface that includes said gripping surfaces of said pipe joint on said first and second pipe sections.

2. The method described in claim 1 wherein: said step of applying a completion covering includes applying a completion covering to said exposed joint surface and around ends of said initial covering.

3. The method described in claim 1, wherein: said step of applying a completion covering around said joint region includes applying a shrink wrap layer around said joint region and applying heat to said shrink wrap layer.

4. The method described in claim 3 wherein: said step of applying a completion covering around said joint region includes wrapping a thermal insulation layer around at least said pipe joint before said step of applying shrink wrap film around said joint region.

5. The method described in claim 1 wherein: said step of applying a completion covering around said joint region includes applying a mold cover around said joint region to leave an annular space between the joint region and the mold cover, including clamping opposite ends of the mold cover to said initial covering on each of said first and second pipes, and injecting a flowable polymer into said annular space.

6. The method described in claim 1 wherein: said initial covering has a thickness of at least 0.2 mm, and said uncovered gripping surface is devoid of a film of a thickness of more than 0.1 mm.

7. A primarily underwater pipeline comprising multiple steel pipe sections connected in tandem, which includes first and second pipe sections with adjacent front ends that have male and female pipe ends with mating grooves that are connected in a pipe joint wherein: said male pipe section has an extreme front end and has a first gripping surface extending rearward by a plurality of centimeters from a rear end of a groove of said male end, and said first pipe has a first initial covering that extends from a location rearward of its gripping surface and along a majority of the length of the first pipe section;said second pipe section has an extreme front end and has a second gripping surface extending a plurality of centimeters rearward of said extreme front end, and has a second initial covering that extends from a location rearward of said gripping surface and along a majority of the length of said second pipe section;a continuous completion covering extending around said pipe joint from a front portion of said first initial covering to a front portion of said second initial covering.

8. The underwater pipeline described in claim 7 wherein: said completion covering comprises a sleeve of shrink wrap polymer that overlaps said pipe joint including said front portions of said first and second initial coverings and that extends continually between said initial coverings and around said gripping surfaces.

9. The underwater pipeline described in claim 7 wherein: said completion covering extends along no more than 6% of the length of each of said first and second pipe sections.