Methods and Apparatus for Installation of a Device about a Marine Structure

Abstract

Methods and apparatus for the installation of VIV suppression during the S-Lay installation of a subsea pipeline. A locking member will be interposed between a pipe and a fairing rotatably mounted on the pipe, sufficient to bias the fairing against rotating. Upon marine application, the locking member will degrade, thereby releasing the fairing.

1 . A system for installing vortex induced vibration suppression or drag reduction devices about a marine structure, comprising: 
 a mechanism for holding the device relative to the structure in a preferred orientation while the structure is being installed; and    wherein the mechanism no longer holds the device relative to the structure in the preferred orientation after the marine structure has been installed.    
   
   
       2 . The system of  claim 1 , wherein the mechanism comprises material that will degrade in a marine environment.  
   
   
       3 . The system of  claim 1 , wherein the structure comprises a tubular, for example a riser.  
   
   
       4 . The system of  claim 1 , wherein the device comprises a fairing.  
   
   
       5 . The system of  claim 1 , wherein the mechanism comprises at least one strap that can be broken after the marine structure has been installed, and/or a pin that can be removed after the marine structure has been installed.  
   
   
       6 . The system of  claim 5 , further comprising a loop, wherein the at least one strap is connected to the loop, wherein the loop can be pulled to break the at least one strap.  
   
   
       7 . The system of  claim 6 , further comprising a plate, wherein the at least one strap and the loop are connected to the plate.  
   
   
       8 . The system of  claim 1 , further comprising a collar about the structure, wherein the mechanism connects the device and the collar, to hold the device relative to the structure in the preferred orientation.  
   
   
       9 . The system of  claim 8 , wherein the collar has a reduced radius portion, and an enlarged radius portion, further wherein the enlarged radius portion extends radially away from the structure.  
   
   
       10 . The system of  claim 1 , wherein the device comprises a fairing having a tail, wherein the preferred orientation relative to the structure during installation comprises turning the tail away from a stinger during a J-lay installation of the structure.  
   
   
       11 . The system of  claim 1 , wherein the mechanism is adapted to position a portion of the device radially away from the structure.  
   
   
       12 . A method comprising: 
 (A) positioning and locking the device in the preferred orientation, such that the device will not be damaged as it passes over a ramp or roller; and    (B) passing the structure and device over the ramp or roller.    
   
   
       13 . The method of  claim 12 , further comprising after passing the structure and device over the ramp or roller, disabling the locking such that the device can move relative to the structure.  
   
   
       14 . The method of  claim 12 , further comprising locking the device to a collar installed about the structure.  
   
   
       15 . The method of  claim 12 , wherein positioning and locking the device comprises securing at least one strap to the device and to the structure or to a second structure connected to the structure.  
   
   
       16 . The method of  claim 15 , further comprising after passing the structure and device over the ramp or roller, breaking the at least one strap to disable the locking such that the device can move relative to the structure.  
   
   
       17 . The method of  claim 12 , wherein positioning and locking the device comprises securing at least one pin to the device and to the structure or to a second structure connected to the structure.  
   
   
       18 . The method of  claim 16 , further comprising after passing the structure and device over the ramp or roller, removing the at least one pin to disable the locking such that the device can move relative to the structure.