Method of arranging a vessel assembly comprising first and second vessels interconnected via a flexible conduit

Abstract

There is provided a method of arranging a vessel assembly including first and second vessels interconnected via a flexible conduit for transferring matter between the first and second vessels, a first end of the conduit in fluid communication with a first manifold of the first vessel, and a second end of the conduit in fluid communication with a second manifold of the second vessel.

1 . A method of arranging a vessel assembly comprising first and second vessels interconnected via a flexible conduit for transferring matter between the first and second vessels, a first end of the conduit in fluid communication with a first manifold of the first vessel, a second end of the conduit in fluid communication with a second manifold of the second vessel, the method comprising the steps of:
 for each of a plurality of combinations of drafts of the vessels, determining a respective manifold height difference between the respective heights of the first and second manifolds above a waterline;   determining a respective maximum operating distance between the vessels at each manifold height difference, wherein each maximum operating distance between the vessels corresponds to the maximum distance to which the vessels can drift apart before the conduit becomes taut at the respective manifold height difference; and   arranging the vessels within a working envelope that corresponds to the plurality of maximum operating distances between the vessels.   
     
     
         2 . The method of  claim 1  wherein the working envelope corresponds to the lower or lowest of the maximum operating distances. 
     
     
         3 . The method of  claim 1  wherein the plurality of combinations of drafts of the vessels includes at least one of:
 a first combination of drafts consisting of a minimum draft of the first vessel and a maximum draft of the second vessel; 
 a second combination of drafts consisting of a maximum draft of the first vessel and a minimum draft of the second vessel; 
 a third combination of drafts consisting of a minimum draft of the first vessel and a minimum draft of the second vessel; or 
 a fourth combination of drafts consisting of a maximum draft of the first vessel and a maximum draft of the second vessel. 
 
     
     
         4 . The method of  claim 3  wherein the maximum draft of each vessel corresponds to the vessel being in a loaded state, and a minimum draft of each vessel corresponds to the vessel being in a ballast state. 
     
     
         5 . The method of  claim 1  wherein the plurality of combinations of drafts includes a fifth combination of drafts for which the manifold height difference is equal to zero. 
     
     
         6 . The method of  claim 1  wherein each maximum operating distance between the vessels is a function of one or more of:
 a length of the flexible conduit; 
 the respective manifold height difference; 
 a depth of the first manifold from the side of the first vessel; 
 a depth of the second manifold from the side of the second vessel; 
 a length of at least one component connected in fluid communication with the conduit and in fluid communication between the manifolds; 
 a list angle of the first vessel; or 
 a list angle of the second vessel. 
 
     
     
         7 . The method of  claim 1 , wherein the vessel assembly includes a safety system, the method including the step of selectively activating at least one safety function of the safety system to bring the vessel assembly to a safe state, wherein the selective activation of the or each safety function is carried out when the vessels are within the working envelope. 
     
     
         8 . The method of  claim 7  wherein the vessel assembly further includes: an emergency release coupling, the emergency release coupling including first and second coupling portions, the first and second coupling portions connected in fluid communication with the conduit and in fluid communication between the manifolds, the first and second coupling portions configured to be selectively connectable and separable to permit selective coupling and separation of the first and second manifolds, and
 wherein the at least one safety function includes at least one of: a first safety function including initiation of a first safe state to perform an emergency shut-down of an operation to transfer matter between the vessels via the flexible conduit; or a second safety function including initiation of a second safe state to cause separation of the first and second coupling portions. 
 
     
     
         9 . The method of  claim 8  wherein the selective activation of the first safety function is carried out at a first drift distance between the vessels, and the selective activation of the second safety function is carried out at a second drift distance between the vessels, the second drift distance being longer than the first drift distance. 
     
     
         10 . The method of  claim 8  wherein the first safe state includes one or more of:
 shut-down of at least one pump configured to pump matter through the flexible conduit; 
 closure of at least one valve configured to control the flow of matter through the flexible conduit, wherein the or each valve is located on either vessel; 
 de-energisation of the emergency release coupling and keep the first and second coupling portions connected to each other; 
 de-energisation of a power source configured to enable charging of a stored energy source for an actuator operable to initiate the separation of the first and second coupling portions; 
 de-energisation of a heating system arranged to control the temperature of the emergency release coupling; 
 de-energisation of one or more solenoid valves switchable to control the operation of the emergency release coupling; 
 maintaining a stored energy source in a fully charged state, wherein the stored energy source is for an actuator operable to initiate the separation of the first and second coupling portions; 
 maintaining closed an activation element, which is switchable to open to initiate the separation of the first and second coupling portions; 
 maintaining open a blocking element, which is switchable to close to configure the first and second coupling portions to block the flow of matter therethrough; or 
 initiation of a timer so as to automatically trigger the activation of the second safety function following expiry of the timer. 
 
     
     
         11 . A vessel assembly comprising first and second vessels interconnected via a flexible conduit for transferring matter between the first and second vessels, a first end of the conduit in fluid communication with a first manifold of the first vessel, a second end of the conduit in fluid communication with a second manifold of the second vessel, wherein the vessels are arranged within a working envelope that corresponds to a plurality of maximum operating distances between the vessels, each maximum operating distance between the vessels corresponds to the maximum distance to which the vessels can drift apart before the conduit becomes taut at a respective one of a plurality of manifold height differences, and each manifold height difference is determined by the difference between the respective heights of the first and second manifolds above a waterline for a respective one of a plurality of combination of drafts of the vessels. 
     
     
         12 . The vessel assembly of  claim 11  wherein the working envelope corresponds to the lower or lowest of the maximum operating distances. 
     
     
         13 . The vessel assembly of  claim 11  wherein the plurality of combinations of drafts of the vessels includes at least one of:
 a first combination of drafts consisting of a minimum draft of the first vessel and a maximum draft of the second vessel; 
 a second combination of drafts consisting of a maximum draft of the first vessel and a minimum draft of the second vessel; 
 a third combination of drafts consisting of a minimum draft of the first vessel and a minimum draft of the second vessel; Hand/nor 
 a fourth combination of drafts consisting of a maximum draft of the first vessel and a maximum draft of the second vessel. 
 
     
     
         14 . The vessel assembly of  claim 13  wherein the maximum draft of each vessel corresponds to the vessel being in a loaded state, and a minimum draft of each vessel corresponds to the vessel being in a ballast state. 
     
     
         15 . The vessel assembly of  claim 11  wherein the plurality of combinations of drafts includes a fifth combination of drafts for which the manifold height difference is equal to zero. 
     
     
         16 . The vessel assembly of  claim 11  wherein each maximum operating distance between the vessels is a function of one or more of:
 a length of the flexible conduit; 
 the respective manifold height difference; 
 a depth of the first manifold from the side of the first vessel; 
 a depth of the second manifold from the side of the second vessel; 
 a length of at least one component connected in fluid communication with the conduit and in fluid communication between the manifolds; 
 a list angle of the first vessel; or 
 a list angle of the second vessel. 
 
     
     
         17 . The vessel assembly of  claim 11  further including a safety system configured to selectively activate at least one safety function to bring the vessel assembly to a safe state, wherein the selective activation of the or each safety function is carried out when the vessels are within the working envelope. 
     
     
         18 . The vessel assembly of  claim 17  wherein the vessel assembly further includes: an emergency release coupling, the emergency release coupling including first and second coupling portions, the first and second coupling portions connected in fluid communication with the conduit and in fluid communication between the manifolds, the first and second coupling portions configured to be selectively connectable and separable to permit selective coupling and separation of the first and second manifolds, and 
       the at least one safety function includes at least one of: a first safety function including initiation of a first safe state to perform an emergency shut-down of an operation to transfer matter between the vessels via the flexible conduit; or a second safety function including initiation of a second safe state to cause separation of the first and second coupling portions. 
     
     
         19 . The vessel assembly of  claim 18  wherein the selective activation of the first safety function is carried out at a first drift distance between the vessels, and the selective activation of the second safety function is carried out at a second drift distance between the vessels, the second drift distance being longer than the first drift distance. 
     
     
         20 . The vessel assembly of  claim 18  or wherein the first safe state includes one or more of:
 shut-down of at least one pump configured to pump matter through the flexible conduit; 
 closure of at least one valve configured to control the flow of matter through the flexible conduit, wherein the or each valve is located on either vessel; 
 de-energisation of the emergency release coupling and keep the first and second coupling portions connected to each other; 
 de-energisation of a power source configured to enable charging of a stored energy source for an actuator operable to initiate the separation of the first and second coupling portions; 
 de-energisation of a heating system arranged to control the temperature of the emergency release coupling; 
 de-energisation of one or more solenoid valves switchable to control the operation of the emergency release coupling; 
 maintaining a stored energy source in a fully charged state, wherein the stored energy source is for an actuator operable to initiate the separation of the first and second coupling portions; 
 maintaining closed an activation element, which is switchable to open to initiate the separation of the first and second coupling portions; 
 maintaining open a blocking element, which is switchable to close to configure the first and second coupling portions to block the flow of matter therethrough; or 
 initiation of a timer so as to automatically trigger the activation of the second safety function following expiry of the timer.