Offhore Pipeline

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Offshore Pipeline InstallationOffshore Pipeline Installation

and Repair and Repair


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Span Mitigation MethodsSpan Mitigation Methods


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Clamp-on Supports with Telescopic LegsClamp-on Supports with Telescopic Legs


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Clamp-on Supports with Auger Screw LegsClamp-on Supports with Auger Screw Legs


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Alteration of Seabed TerrainAlteration of Seabed Terrain


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uo!anc! moduleuo!anc! module


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Pipeline installationPipeline installationBefore the actual operation of subsea

pipelines the system is installed on theseabed.

To ensure mechanical integrity, the pipeline

should be able to withstand both static anddynamic stresses involved during theinstallation.

Installation of subsea pipelines is commonlydone according to one of the following threeinstallation methods:

J-lay (intermediate to deep water); J-lay (intermediate to deep water);

S-lay (shallow to intermediate-deepS-lay (shallow to intermediate-deep


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A method for installing subsea pipelines in deepwater is

by J-lay installation. ipe stal!s consisting of si" with atotal length of #$m are upended and welded to theseagoing pipe in a near vertical ramp.

The ramp angle is chosen in such a way that it is in linewith the pipe catenary to the seabed. The J-lay method isvery suitable for deepwater as the pipe leaves the laysystem in an almost vertical position. The pipeline is onlybent once during installation %at the seabed& which is

advantageous for installing pipelines that are sensitiveto fatigue.

'ompared to other lay methods, J-lay has a relatively lowproduction rate due to the single welding station. The J-

lay method is less suitable for shallow waters as thisre uires a de arture an le close to hori)ontal.

J lay J lay


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*hen using the +-lay installation method, pipe oints

welded onboard leave the vessel hori)ontally and areguided by a stinger - a structure on the bac! of the shipthat supports the seagoing pipe string to control its bendradius.

ue to its high production rate and the possibility toinstall concrete coated pipe, +-lay is e"tremely suitablefor pipe installation in shallow and intermediate waters.

/arger water depths are e(ually possible but re(uire avery long stinger, turning +-lay into a less practical ande0cient solution.

S layS lay


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A method for installing 1e"ible and rigid subsea pipelinesis by 2eel-lay. /ong pipe segments are welded, tested andcoated onshore and then spooled onto a large verticalpipe reel in one continuous length.

3nce the 2eel-lay vessel is in position, the pipe isunspooled, straightened and over boarded as the vesselmoves forward.

Reel layReel lay


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Offhore Pipeline

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