Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Submerging – raising – or manipulating line of pipe or cable...
Patent
1998-01-26
1999-07-13
Taylor, Dennis L.
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Submerging, raising, or manipulating line of pipe or cable...
405158, 405171, F16L 104
Patent
active
059217138
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a new method by which, in situ and without the use of divers or other personnel operating at depth, two underwater pipelines, with diameters up to 40" and also over, can be connected, particularly suitable for great depths and big diameters.
DESCRIPTION OF THE RELATED ART
Various methods are already known in the art for connecting underwater pipelines. Apart from the one used for low and medium depths, based on hyperbaric welding requiring the use of immersed personnel, which can be effected satisfactorily to a maximum depth of the order to 200 meters both because of problems involved in the welding itself and because of problems concerning the operating capacity of the personnel, which is considerably reduced under the excessive external pressure, the other methods used for such connection intervention, based on system not requiring the use of immersed personnel, are mainly limited by two principal factors: pipeline diameter and water depth.
Pipeline diameter can be considered the main limiting parameter, in fact all the known methods in the state of the art require one of the two pipeline sections to be connected to be able to be pulled up to the other section being fixed. The pull forces required for this operation increase proportionally with the pipeline diameter and operations with these characteristics have been performed only for pipeline up to 20".
Water depth, instead, is a critical parameter due to the fact that all the known methods in the state of the art require a guidance apparatus from surface to seabed to the aid their installation on the seabed. Such guidance apparatus is composed by steel guide lines connected on one side to the seabed structure, while on the other side to the ship used as support on surface. This guidance method, at the moment, is considered satisfactory up to a depth of the order of 400 meters because of problems involved in the tensioning of said guide lines. Because of this, there is a need for an alternative method able to overcome both the pipeline diameter and depth barriers while ensuring the same operating reliability of the existing systems.
The closest prior art is NO-A-932563, which discloses a method for connecting underwater pipelines, whereby one of the pipeline sections to be connected is pulled up to the other section. However, the pulling forces for such an operation are very large and can only be carried out for smaller pipelines.
SUMMARY OF THE INVENTION
The object of the present invention is to obviate said drawbacks by providing a method allowing a complete remote connection of underwater pipelines, not requiring any pull operation to one of the two pipeline sections to be connected, and not requiring the use of guide lines for its installation on the seabed, to be performed by a ship with a simple crane.
The present invention solves the problem outlined above through the use of a mechanical joint, formed by connectors, provided with telescopic capacity avoiding any pull requirement for both sections of the pipeline, and through the use as installation aid in the preferred embodiment of a guidance system installed only seabed without requiring any connection with the surface means.
The method for connecting underwater pipelines, object of the present invention, using a crane equipped support ship and remotely operated vehicles for seabed works and assistance, is characterised by including the following steps: fixed frame; chains and an installation skid, by a lay barge, and abandonment of the said outboard pipeline in a defined lay down area; guide pins, within the said seabed fixed frame, by the said onboard crane, followed by the locking of the said subsea winch on the said guide pins through hydraulic latches; actuation of the said winch by the said vehicle to unwind the cable of the said subsea winch, aided by a second remotely operated vehicle bringing and connecting the end of the said cable to the outboard pipeline, winding of the said cable and following deflection of the said outbo
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Corbetta Giovanni
d'Aloisio Guido
Gjessing Harald Ottar
Haugen Finn Germand
Radicioni Alessandro
Kongsberg Offshore a.s
Snamprogetti S.p.A.
Taylor Dennis L.
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