Allseas Group S.a.

Allseas Engineering B.v.

Robert Paul Hovinga

Klaas Boudewijn Van Gelder

Jacobus Cornelis Wijsman

Peter Ronald De Jong

Eugene A Bajema

Arnold Andries Van Den Dool

Gerhardus A Stenfert

The invention relates to a method for assembling and disassembling an installation present on a seabed, for instance a pipeline lying on a seabed, wherein components, for instance pipe flanges, are mutually attached by means of nut and bolt connections and the nut and bolt connections are released and/or secured by means of a wrench. Nut and bolt connections are herein released by divers using a wrench. This is heavy and difficult work. It is impossible for divers to operate at considerable depth. Complicated and very costly pipeline connections are then applied which can be released and secured without divers. The invention has for its object to reduce the stated drawbacks of the known method. To this end at least one wrench is used, of which an engagement cup for engaging a nut and/or a bolt head in axial direction of a nut and bolt connection for manipulating is displaceable relative to a cup carrier counter to spring action.

Method and apparatus for assembling or disassembling an installation present on a seabed

A method for lifting a sea platform with its substructure attached from a seabed and moving that platform to a different location. Use is made of flotation bodies which are filled with water and attached to the substructure. The flotation bodies can be emptied of some water to provide greater flotation and can be rotated around a horizontal axis to facilitate movement of the entire assembly under various sea conditions.

Method for lifting a sea platform from the substructure

During laying of a pipeline on a surface located under water, on a vessel a pipe is fitted to a pipe string of the pipeline, in each case during a fitting step. Herein during the fitting step the vessel is moved substantially continuously in lengthwise direction of the pipe string while a pipe is fitted to the pipe string by means of positioning means moved relative to the vessel and by means of welding means moved relative to the vessel. According to the invention, a train of positioning means, welding means and clamping means is moved during an operational phase relative to the vessel in lengthwise direction of the pipe string in principle together with the pipe string and during a resetting phase set between two successive operational phases this train is displaced in the direction of the prow of the vessel relative to the pipe string and relative to the vessel. The pipe string is herein held fixedly on the train by means of the clamping means and the train is held fixedly on the vessel by means of coupling means.

Method and installation for laying a pipeline

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Naaldwijk, Netherlands

Robert Paul Hovinga