Inspection and/or maintenance method and associated apparatus

Abstract

An isolation method, and apparatus, for isolating and temporarily sealing closed an opening of a marine vessel to prevent ingress of fluid into or through the opening, sealing an internal side of the opening from an external side of the opening. A positioning line is provided between a connection point and the sealing apparatus, with the positioning line being tensioned to pull the sealing apparatus towards the opening. The method is performed entirely diverlessly, with no personnel required in or under the water at any stage of the method, including during connecting the positioning line to the connection point and pulling the sealing apparatus onto and/or into the opening.

1 . An isolation method for isolating and temporarily sealing closed an opening of a marine vessel to prevent ingress of fluid into or through the opening, sealing an internal side of the opening from an external side of the opening, the isolation method comprising sealing the opening with a sealing apparatus, wherein the method comprises:
 connecting the sealing apparatus to at least one connection point associated with the opening of the marine vessel, the connection point being used to connect a positioning line relative to the opening;   providing the positioning line between the connection point and the sealing apparatus;   tensioning the positioning line such that the sealing apparatus is pulled towards the connection point to maneuver the sealing apparatus into a desired position relative to the opening; and   sealing closed the opening with the sealing apparatus;   wherein the method is performed entirely diverlessly, with no personnel required in or under the water at any stage of the method, including connecting the positioning line relative to the connection point and pulling the sealing apparatus onto and/or into the opening.   
     
     
         2 . The method of  claim 1 , wherein the opening is an aperture in or through the hull of the marine vessel; and the marine vessel comprises at least one of: a ship; a Floating Offshore Installation (FOI); a wholly or partially submersible structure; a Floating Production, Storage and Offloading unit (FPSO); a Mobile Offshore Drilling Unit; or an Accommodation Vessel. 
     
     
         3 . The method of  claim 1 , wherein the method comprises further tensioning the positioning line so as to pull the sealing apparatus onto or into the opening to provide the closed seal. 
     
     
         4 . The method of  claim 1 , wherein the method comprises tensioning the positioning line using a line tensioner located at or on the sealing apparatus, the line tensioner comprising one or more of: a winch, a powered pulley, a reel, and a motor; and the method comprises controlling the positioning of the sealing apparatus remotely, from surface. 
     
     
         5 . The method of  claim 1 , wherein the method comprises releasably mechanically attaching the positioning line to the connection point, the connection point being at or proximal to the opening and effectively defining an anchor point for the positioning line, once attached; and
 cleaning the opening with a diverless operation before the positioning line is attached.   
     
     
         6 . The method of  claim 1 , wherein the method comprises providing a plurality of positioning lines between a plurality of connection points associated with a single opening; and the sealing apparatus comprises a plurality of line tensioners in the form of a plurality of winches; and the method comprises tensioning each positioning line with a respective winch associated with each positioning line; and tensioning each of the plurality of positioning lines to a similar tension. 
     
     
         7 . The method of  claim 1 , wherein the method comprises providing an interim attachment of the sealing apparatus mechanically with the tensioning of a line tensioner; and providing a final attachment of the sealing apparatus by creation of a hydrostatic pressure differential by draining fluid from one side of the sealing apparatus. 
     
     
         8 . The method of  claim 1 , wherein the sealing apparatus comprises one or more sensors; and the method comprises tensioning the positioning line to a tension of at least 100 kg. 
     
     
         9 . (canceled) 
     
     
         10 . The method of  claim 1 , wherein the method comprises maintaining tension in the positioning line so as to maintain the seal closed; and
 locking the positioning line to mitigate against a power failure or interruption; the method comprising activating a lock in advance of and/or in response to a power failure or interruption.   
     
     
         11 . (canceled) 
     
     
         12 . The method of  claim 1 , wherein the method comprises releasing the sealing apparatus and removing the sealing apparatus from the opening after completion of an operation/inspection; the method comprising releasing the positioning line by releasing a connection associated with an end of the positioning line at the connection point; and loosening the positioning line; wherein the releasing is performed before or after the loosening. 
     
     
         13 . The method of  claim 1 , wherein the method comprises transporting the sealing apparatus through a body of water by lowering the sealing apparatus from at or near surface, at least partially under gravity with a sufficiently negatively buoyant sealing apparatus suspended from a support line so as to maintain a tension in the support line; and the method comprises controlling the position of the sealing apparatus by monitoring and controlling a payout length of the support line, progressively paying out a sufficient length of the support line so as to allow the sealing apparatus to descend to a depth corresponding approximately to a depth of the opening. 
     
     
         14 . The method of  claim 1 , wherein the method comprises attaching the positioning line to the connection point using a Remotely Operated Vehicle (ROV);
 attaching the ROV to the sealing apparatus; and   the method further comprises using the ROV to position the sealing apparatus at a correct depth corresponding to that of the opening.   
     
     
         15 . (canceled) 
     
     
         16 . The method of  claim 14 , wherein the method comprises transporting and positioning the sealing apparatus using a combination of general lowering under suspension without a ROV and then fine positioning with the ROV connected to the sealing apparatus; and
 only mechanically connecting the ROV to the sealing apparatus, without electrical or optical connections.   
     
     
         17 . (canceled) 
     
     
         18 . The method of  claim 14 , wherein the method comprises remotely controlling a line tensioner and/or the ROV to remotely control the sealing apparatus and/or attachment of connector/s of the positioning line and/or a release mechanism. 
     
     
         19 . The method of  claim 14 , wherein the method comprises sequentially:
 positioning the sealing apparatus with the ROV;   attaching the sealing apparatus to the opening;   disconnecting the ROV from the sealing apparatus;   performing operations with the sealing apparatus attached to the opening;   opening the opening with the ROV; and   reconnecting the ROV to the sealing apparatus.   
     
     
         20 . The method of  claim 14 , wherein the method comprises isolating a plurality of sea chests sequentially with a single ROV. 
     
     
         21 . The method of  claim 1 , wherein the method comprises sealing over the opening by sealing against one or more surface/s around the opening, forming a seal around the opening; and/or the method comprises sealing in or within the opening by inserting at least a portion of the sealing apparatus into the opening. 
     
     
         22 . (canceled) 
     
     
         23 . A sealing apparatus for performing the method of  claim 1 , the sealing apparatus comprising:
 a sealing portion for sealingly engaging the opening, with the sealing apparatus being configured to attach to a hull, at or near the opening in the hull; and   a plurality of line tensioners, the line tensioners being configured to tension a plurality of positioning lines to pull the sealing apparatus onto and/or into the opening.   
     
     
         24 . The sealing apparatus of  claim 23 , wherein the sealing apparatus comprises a blanking plate with a plurality of winches mounted thereto, the winches each comprising a respective positioning line for attaching the blanking plate to and/or in the opening;
 and the apparatus comprises a quick release connector at the opposite end of each positioning line from the respective winch.   
     
     
         25 . The sealing apparatus of  claim 23 , wherein the sealing apparatus comprises:
 an engagement member for engagement with or by a ROV engagement member, the sealing apparatus engagement member being configured to allow gripping and/or manipulation of the sealing apparatus by the ROV; and   a valve;   wherein the sealing apparatus is powered and controlled with power and control lines running via an umbilical/s to surface.   
     
     
         26 . (canceled)