Sea Engineering Associates, Inc.

Modec International, LLC

David E Chaplin

Pieter G Wybro

Shukai Wu

Johannes J Treu

Terrence Kryska

A method and system for attaching a TLP to its tendons using pull-down lines to rapidly submerge the hull to installation draft while compensating for inherent hull instability during submergence and to provide motion arrest and aid in station keeping. The system includes tensioning devices mounted on the TLP, usually one for each tendon. Each tensioning device is equipped with a pull-down line which is connected to the corresponding tendon. The TLP hull is submerged to lock-off draft by applying tensions to the pull-down lines connected to the top of the tensions, or by a combination of applying tensions to the pull-down lines and ballasting the hull. As the tensioners take in pull-down line, the hull submerges, i.e. the draft increases. After lock-off, high levels of tension in the pull-down lines can be rapidly transferred to the connection sleeves by slacking the pull-down lines, thus allowing the TLP to be made storm-safe much faster than by prior art methods which require de-ballasting to tension the tendons. In concert with TLP installation, the method may be used attach the mooring tendons to the seabed by suspending and lowering the tendons into their foundation receptacle in the seabed.

Method of installation of a tension leg platform and tendons therefor

An apparatus and method for ballasting and de-ballasting a vessel having a hull with several watertight ballast compartments. In a first embodiment, a pressure tank is isolatably and fluidly coupled to a common sea chest, to the atmosphere, to ballast compartments via a distribution manifold, and to a source of compressed gas. The pressure tank is first vented and filled with water from the sea chest, then isolated. The filled tank is then coupled to a ballast tank and the source of compressed gas, which displaces water from the tank to the ballast compartment. In other embodiments, ballasting is by venting and flooding compartments using individual sea chests located within the ballast compartments or a firewater system. For de-ballasting, compressed gas displaces ballast water through overboard discharges, through the common sea chest via the pressure tank, or through individual sea chests located within the ballast compartments.

Ballast system for tension leg platform

Method of installation of a tension leg platform

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Magnolia, TX, United States of America

David E Chaplin