Holding back elongate elements during subsea operations
AssigneeAcergy France SAS
InventorsOlivier Lodeho, Johan Janot, Vincent Loentgen
Life of this patent
Estimating the term…
Abstract
A subsea pipeline coated with a thermally insulating coating has a radially outer surface shaped to define external hold-back formations. In a J-lay operation, the weight load of a pipeline catenary is held back using a complementary bushing or clamp of an installation vessel engaged with the hold-back formations. The weight load is transferred from the catenary to the bushing or clamp by shear forces acting through the coating. The coating extends continuously along the pipe and is interposed between the hold-back formations and the underlying pipe. The hold-back formations may be integral with the coating.
Claims23
A pipe joint for offshore fabrication and installation of a pipeline in a J-lay operation, the pipe joint comprising:
- a length of pipe;
- a thermally-insulating coating around the length of pipe;
- and
- a radially outer surface shaped to define a series of external radially-projecting hold-back formations disposed in longitudinal succession along the pipe joint, the hold-back formations configured to facilitate suspending of the pipe joint during the J-lay operation, each hold-back formation being a ridge that extends continuously around the pipe joint circumferentially;
- wherein the coating extends continuously along the pipe on a radially inner side of each hold-back formation and is interposed between each hold-back formation and the pipe;
- and wherein when a central longitudinal axis of the pipe joint is upright a downwardly-facing face of each hold-back formation has a substantially frusto-conical surface inclined at an acute angle relative to the central longitudinal axis of the pipe joint.
A hold-back bushing or traveling clamp for use in J-lay operations, the bushing or clamp being annular and having a radially inner surface shaped to engage with one or more external hold-back formations projecting radially from a pipe joint and configured to facilitate suspending of the pipe joint during a J-lay operation, the or each hold-back formation being a ring that extends continuously around the pipe joint circumferentially;
- wherein the inner surface comprises at least one circumferentially-extending groove arranged to receive the or each of said hold-back formations, the or each groove defined by a pair of oppositely-inclined generally frusto-conical faces that converge with each other in a radially outward direction, the faces of the pair having differing acute angles of inclination relative to a central longitudinal axis of the bushing or clamp.
In combination, a bushing or clamp of and a pipe joint for offshore fabrication and installation of a pipeline in a J-lay operation, the pipe joint comprising:
- a length of pipe;
- a thermally-insulating coating around the length of pipe;
- and
- a radially outer surface shaped to define a series of external radially-projecting hold-back formations disposed in longitudinal succession along the pipe joint, the hold-back formations configured to facilitate suspending of the pipe joint during the J-lay operation, each hold-back formation being a ridge that extends continuously around the pipe joint circumferentially;
- wherein the coating extends continuously along the pipe on a radially inner side of each hold-back formation and is interposed between each hold-back formation and the pipe;
- wherein when a central longitudinal axis of the pipe joint is upright, a downwardly-facing face of each hold-back formation has a substantially frusto-conical surface inclined at an acute angle relative to the central longitudinal axis of the pipe joint;
- the bushing or clamp being annular and having an inner surface comprising circumferentially-extending grooves opposed to and complementary with each hold-back formation of the pipe joint to receive each of said hold-back formations, each groove being defined by a pair of oppositely-inclined generally frusto-conical faces that converge with each other in a radially outward direction, the faces of the pair having differing acute angles of inclination relative to a central longitudinal axis of the bushing or clamp.
A method of manufacturing a pipe joint for offshore fabrication and installation of a pipeline in a J-lay operation, the method comprising:
- applying a thermally-insulating coating onto a length of pipe;
- and
- forming or attaching a series of external radially-projecting hold-back formations onto the coating so the formations are disposed in longitudinal succession along the pipe joint, the or each hold-back formation being a ridge that extends continuously around the pipe joint circumferentially and being configured to facilitate suspending of the pipe joint during the J-lay operation;
- wherein the hold-back formations are formed or attached such that when a central longitudinal axis of the pipe joint is upright, a downwardly-facing face of each hold-back formation has a substantially frusto-conical surface inclined at an acute angle relative to the central longitudinal axis of the pipe joint.
A J-lay method for offshore fabrication and installation of a pipeline, the method comprising:
- attaching a pipe joint to an upper end of a pipe string catenary suspended from an installation vessel, the pipe joint comprising a thermally-insulating coating around a length of pipe, which coating extends continuously along the pipe and is interposed between the pipe joint and a series of external radially-projecting hold-back formations disposed in longitudinal succession along the pipe, each hold-back formation being a ridge that extends continuously around the pipe joint circumferentially and being configured to facilitate suspending of the pipe joint during a J-lay operation, wherein when a central longitudinal axis of the pipe joint is upright, a downwardly-facing face of each hold-back formation has a substantially frusto-conical surface inclined at an acute angle relative to the central longitudinal axis of the pipe joint;
- and
- holding back a weight load of the catenary using a bushing or clamp of the vessel engaged with each hold-back formation.
Dependencies are inferred from the claim text.