Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B27/00—Arrangement of ship-based loading or unloading equipment for cargo or passengers
  • B63B27/24—Arrangement of ship-based loading or unloading equipment for cargo or passengers of pipe-lines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B27/00—Arrangement of ship-based loading or unloading equipment for cargo or passengers
  • B63B27/24—Arrangement of ship-based loading or unloading equipment for cargo or passengers of pipe-lines
  • B63B27/25—Arrangement of ship-based loading or unloading equipment for cargo or passengers of pipe-lines for fluidised bulk material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B27/00—Arrangement of ship-based loading or unloading equipment for cargo or passengers
  • B63B27/30—Arrangement of ship-based loading or unloading equipment for transfer at sea between ships or between ships and off-shore structures
  • B63B27/34—Arrangement of ship-based loading or unloading equipment for transfer at sea between ships or between ships and off-shore structures using pipe-lines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
  • B65H26/00—Warning or safety devices, e.g. automatic fault detectors, stop-motions, for web-advancing mechanisms
  • B65H26/02—Warning or safety devices, e.g. automatic fault detectors, stop-motions, for web-advancing mechanisms responsive to presence of irregularities in running webs
  • B65H26/04—Warning or safety devices, e.g. automatic fault detectors, stop-motions, for web-advancing mechanisms responsive to presence of irregularities in running webs for variation in tension

Definitions

• the present invention relates generally to the field of oil and gas production, and towards offloading and storage facilities.
• the present invention relates to an overload protection system for offloading facilities offshore and onshore.
• a floating production, storage and offloading (FPSO) unit is a floating vessel used by the offshore oil and gas industry for the processing of hydrocarbons and for storage of oil.
• An FPSO vessel is designed to receive hydrocarbons produced from nearby platforms or subsea template, process them, and store oil until it can be offloaded onto a tanker or, less frequently, transported through a pipeline.
• FPSOs are preferred in frontier offshore regions as they are easy to install, and do not require a local pipeline infrastructure to export oil.
• FPSOs can be a conversion of an oil tanker or can be a vessel built specially for the application.
• FIG. 1 A simplified FPSO 10 and offloading tanker 12 is shown in Figure 1, where the tanker 12 is moored to the FPSO 10 via a hawser 14, and the hose string 16 provides a fluid connection between the FPSO 10 and the tanker 12 allowing, for example, crude oil to be transferred from the FPSO to the tanker.
• the offloading system 18 may consist of a rotating hose reel 20 accommodating hose(s) that can be deployed overboard and connected to the tanker 12 to facilitate the offloading process.
• the hose string 16 is connected to the offloading reel 20 at a gooseneck connection 22 secured by a bolted flange (not shown).
• the offloading zones 24, 25 are defined from an analysis of the predominant environmental conditions for the specific proposed location in which the FPSO 10 is operational. In the event the conditions change during the offloading process to the point that the tanker position cannot be maintained, the tanker 12 will disconnect and can in many cases reconnect safely to the offloading system 18 on the opposite side of the FPSO 10.
• Recent FPSO developments lead to the consideration of an expanded offloading zone 25 providing an increase of the scope of operation and consequently an increase of the opportunity for the offloading to take place.
• An expanded offloading zone 25 also justifies a reduction from two separate offloading systems 18 at opposite sides of the FPSO 10 to a single offloading system 18.
• the extent 26 within which an emergency load condition can be seen in the hose string 16 for those systems currently in use are predominantly governed by the size and position of the offloading zone 24, 25. Consequently, the extent 26 to which an emergency load can be applied to the offloading system via the hose 16 is greatly increased by the extended offloading zone 25.
• the new conditions provided by the extended offloading zone 25 may impose loading regimes upon the hose 16, specifically the hose connection to the offloading system 18, that have not yet been considered or tested for the currently available equipment, and may go beyond the structural capabilities of the hose 16.
• the new loading regimes imposed by the extended offloading zone 25 are significantly more stringent than the loading regimes imposed by the offloading zone 24 generally applied to similar systems.
• currently available hoses 16 are structurally not capable of sustaining the anticipated new load conditions without the severe risk of rupture. A rupture of the hose string 16 during offloading would invariably result in a severe pollution incident through loss of the product (e.g. crude oil) directly into the sea.
• Figure 4(a) depicts the sectors (hatched) of the extended offloading zone 25 where new loading regimes may be imposed to the hose string 16 during offloading.
• Figure 4(b) shows an example of a hose string 16, typically consisting of many segments 16A that are joined by flange connections 28, each segment 16A comprising rigid steel end fittings (not shown) coupled to a flexible composite rubber tube.
• a hose string 16 typically consisting of many segments 16A that are joined by flange connections 28, each segment 16A comprising rigid steel end fittings (not shown) coupled to a flexible composite rubber tube.
• Such an arrangement is capable of withstanding considerable axial load and may also withstand bending of the rubber tube to a radius of around four times the diameter of the flexible tube.
• the hose 16 and its flange connection 28 are not capable of simultaneously sustaining large tensile loading and a signi ficant misalignment angle. Thus, its capacity for applied bending moments is severely limited.
• an extended offloading zone 25 significantly increases the area in which the emergency release coupling load could be imposed upon the offloading system 18 via the hose 16.
• the hose 16 does not have the structural capability of sustaining such potential loads throughout the entire scope of application during offloading. Accordingly, it is an object of the present invention to provide a system that is adapted to limit the potentially imposed bending moments within the hose string and segments to a predetermined maximum magnitude that is within the permissible range of the minimum bending radius (MBR) of the hose string 16.
• Preferred embodiment(s) of the invention seek to overcome one or more of the above disadvantages of the prior art.
• a tensile overload protection system for a loading hose comprising:
• At least one first tether having a first end and a second end, coupleable between a predetermined segment of a hose string and a hose string support structure, so as to transfer a tensile load above a predetermined threshold from the hose string to said at least one first tether;
• a first connection member connectable to the hose string and comprising at least one first anchor point adapted to receive and fix said first end of said at least one first tether
• a second connection member operatively coupleable to the hose string support structure and comprising at least one second anchor point adapted to receive and fix said second end of said at least one first tether.
• the overload protection system is functioning in synergy with the offloading system, so as to only deploy and engage the tether (s) when the hose string is stressed above a predetermined magnitude without interfering with the functionality of the offloading system.
• the system of the present invention can be permanently installed to the offloading system providing an additional and improved safety mechanism to the hose string.
• the first connection member may be adapted to be coupled to any one of the flange members connecting two successive segments of the hose string. This provides the advantage of improved adaptability and functionality due to integrated flange members suitable for connecting the tether(s).
• the tensile overload protection system may further comprise at least one first guide member connectable to the hose string and adapted to guidingly support said at least one first tether.
• the guide member may comprise at least one guide loop.
• the at least one first guide member may be adapted to be coupled to any one of the flange members connecting two successive segments of the hose string. This provides the advantage of functionally aligning the tether (s) with the longitudinal axis of the hose string ensuring that tensile loads applied to the hose string are transferred directly to the tether(s) and offloading reel, as well as, minimising the risk that any slack of the tether(s) may interfere with any movement of the hose string during offloading.
• the at least one second anchor point may be a pivot anchor.
• the at least one second anchor point may comprise at least one sheave adapted to operatively receive said at least one first tether.
• the second connection member may further comprise a tether stowage adapted to receive and stow any excess portion of said at least one first tether.
• the tether stowage may comprise a predetermined groove cut in the hose string support structure adapted to receive and retain any excess portion of said at least one first tether.
• the tether stowage may further comprise a retract mechanism adapted to retract any excess portion of said at least one first tether into said stowage at a predetermined tensile force. This provides the advantage of minimising any slack of the tether(s) when not engaged, i.e. the tensile load on the hose sting is below a predetermined threshold.
• the threshold is determined by the structural characteristics of the hose string when bent within the limits of the extended offloading zone and under a tensile load.
• An automatic retracting mechanism such as a spring loaded cable retractor, provides the advantage that the tether(s) is kept taut during operation with the tensile load below which the overload protection system is deployed.
• the tensile overload protection system may further comprise an overload detector adapted to indicate when the tensile load is above said predetermined threshold and transferred from the hose string to said at least one first tether.
• the overload detector may be adapted to provide any one of a visual and/or audible signal upon deployment of said at least one first tether.
• the visual signal may be a coloured marking on said excess portion of said at least one first tether.
• the audible signal may be actuated when the tensile load applied to the hose string exceeds said predetermined threshold.
• the tensile overload protection system may further comprise at least one second tether, having a first end and a second end.
• the first connection member may further comprise at least one third anchor point adapted to receive and fix said first end of said at least one second tether.
• the at least one second anchor point may be further adapted to receive and fix said second end of said at least one second tether.
• the at least one first and at least one second tether are aligned in parallel to the longitudinal axis of at least one hose string segment.
• the at least one first tether and/or said at least one second tether may be made of a flexible element having a tensile strength that is higher than the tensile strength of the hose string.
• the flexible element may be formed from any one of a metal, a synthetic rope or a composite material having a predetermined tensile strength that is higher that the tensile strength of the hose string.
• the length of said at least one first and/or second tether may be so as to allow a predetermined maximum tensile load and respective predetermined maximum stretch of the hose string before said tensile overload protection system is engaged.
• an offloading system comprising a rotatable hose reel configured to store a hose string, an offloading connection adapted to connect to the hose string, and a tensile overload protection system according to the first embodiment of the present invention.
• Figure 1 shows a simplified offshore setup for an offloading FPSO in engagement with a tanker
• Figure 2 shows a commonly used offloading system comprising an offloading reel, gooseneck connection and hose string;
• Figure 3 shows examples of (a) standard offloading zones (b) an extended offloading zone, and (c) & (d) the extent of the offloading zones in (a) and (b);
• Figure 4 shows an example of (a) an extended offloading zone and the regions for limited 'full-load-application', and (b) and bent section of a typical hose string comprising hose segments and flange connections ;
• Figure 5 illustrates a first embodiment of the overload protection system when operatively coupled to an offloading system
• Figure 6 shows a side view of (a) the engaged overload protection system and (b) a schematic diagram of the movement of the tether(s) during movement of the hose string demonstrating that the tether system will remain passive until such times as the hose string is forced out of position through the application of an accidental loading condition;
• Figure 7 shows (a) a perspective view and (b) a front view of the hose reel, goose neck, hose string and coupled overload protection system including guide members;
• Figure 8 shows (a) a perspective view and (b) a top view of the flange member coupled to the hose string with a single tether connected to each side of the hose string;
• Figure 9 shows a detailed (a) perspective view and (b) bottom view of the second connection member integrated in the offloading reel and two tethers anchored to the second connection member;
• Figure 10 shows (a) a perspective view and (b) side view of a first example of the second anchor point in form of a pivot anchor for two tethers;
• Figure 11 shows (a) a perspective view and (b) a sectional side view of a second example of the second anchor point in form of a sheave anchor for one tether;
• Figure 12 shows a schematic diagram of an extended offloading zone and its risk regions during offloading.
• a first embodiment of the overload protection system 100 includes two flexible tethers 102 and 104 that are coupled to the original flange connectors 28 via a flange adaptor 106.
• the tethers 102, 104 may be formed from metal wires, or steel ropes or synthetic ropes or any other suitable compound to form a flexible tether 102, 104.
• the flange adaptor 106 may be a flange member that is coupled between two existing flange connectors 28, but may also be a simple disc member (not shown) compatible with and connectable to the flange connectors 28 of the hose string.
• the flange adaptor 106 is a flange member 106 having an anchor point 108 for each tether 102 and 104 on either side of the hose string 16 (see Figure 8).
• the anchor points 108 may be pivot anchors allowing the tether 102, 104 to pivot about a pivot axis of the anchor point 108 and align the tether(s) 102, 104 and the hose string axis under tensile load.
• the pivot anchor may be formed by a simple pin which forms a pivot axis for a looped end of the tethers 102, 104, or, the anchor points 108 may include a hinge connectable to the ends of the tethers 102, 104 allowing the tethers 102, 104 to move freely about the pivot axis of the hinge. Any suitable hinge mechanism may be used for the anchor points 108.
• the flange adaptor 106 may be mountable to the outer surface of the existing flange connectors 28. It is understood by the person skilled in the art that any suitable mount that is adapted to provide at least one anchor point 108 for at least one tether 102, 104 may be used.
• a tether guide 110 may be provided at a more proximal flange connection allowing the tethers 102, 104 to be aligned with the longitudinal axis of the hose string 16.
• the tether guide 110 may simple be a guide loop (not shown) attached to a disc member that is operatively coupleable between two flange connectors 28.
• any other guide e.g. a sheath
• the tether guide 110 may be mounted to the outer surface of the hose string 16.
• the reel anchor 112 includes a reinforced segment 114 mounted to the reel drum 20, wherein a pivot anchor is operatively mounted to the inside of the reel drum.
• a groove 116 in the reinforced segment 114 allows the tethers 102, 104 to pass through the reel drum wall in order to attach to the pivot anchor 118.
• tethers 102 and 104 share the same pivot anchor 118.
• the groove 116 may be formed so as to allow any slack tether 102, 104 to be stowed away inside the reel drum 20.
• the groove may be 'S'-shaped so that the slack tethers 102, 104 can be placed inside the reel drum 20.
• the reel anchor 112 may include a spring biased retractor (not shown) that is adapted to automatically retract any slack of the tethers 102, 104 keeping the tethers 102, 104 taut even when the overload protection system 100 is not deployed / engaged due to an excessive tensile load.
• the spring biased retractor (not shown) may be mounted to the tethers 102, 104 between the pivot anchor 118 and the reinforced segment 114 so as to only retract the slack portion of the tethers 102, 104, and to disengage when the overload protection system 100 is deployed. It is understood by the person skilled in the art, that any suitable retractor mechanism may be used to pull in any slack of the tethers 102, 104. It is understood that the retracting force applied to the tether (s) 102, 104 is less than a predetermined threshold of the tensile load applied to the hose string 16.
• the reel anchor 112 may include a sheave 120 mounted inside the reel drum 20 to the reinforced segment 114.
• a sheave 120 When using the sheave 120, only a single tether 102 is required to provide a dual guided tether arrangement running the tether 102 through the sheave 120 and connecting both ends to the anchor points 108 at the flange adaptor 106.
• a retractor mechanism may be operatively coupled to the sheave 120 so as to retract any slack of the tether 102 when the overload protection system 100 is not deployed.
• the overload protection system 100 may include an audible and/or visual indicator adapted to provide a visual and/or audible alarm when the tensile load exceeds a predetermined magnitude and the overload protection system 100 is deployed by tautening the tether (s) 102, 104 between the anchor points 108 and 112.
• a visual marker may be a coloured section of the tether(s) 102, 104 that only becomes visible when the slack of the tether is pulled out of the stowage inside the reel drum 20 at a predetermined tensile load.
• an audible signal may be provided when the tensile load applied to the tether (s) 102, 104 exceeds a predetermined magnitude.
• the audible signal generator may be actuated via a tensile tester operatively coupled to the tether(s) 102, 104.
• a tensile tester operatively coupled to the tether(s) 102, 104.
• the hose catenary will be forced into alignment with the direction of the applied load 200 (see Figure 6, hose orientation (i) ⁇ .
• the direction of this load can be from a large area about the front and sides of the offloading system 18.
• the tether (s) 102, 104 When the hose string is pulled into alignment with the tensile load path the tether (s) 102, 104 are deployed and tautened against the anchor points 108 and 112 transferring the potentially damaging tensile load from the hose string 16 and goose neck 22 to the hose reel structure 20 of the offloading system 18.
• a coloured section of the tether(s) becomes visible indication the deployment of the overload protection system 100, Consequently, and since the tensile stress within the hose string 16 is limited to a predetermined maximum, the maximum bending moment that may be generated is also limited to not exceed a predetermined magnitude.
• the predetermined magnitude of the tensile load allowed within the hose string is defined to be well below the structural limitations of the hose string under tensile load and when bent to the MBR.
• the tether system will go slack and become passive again (see Figure 6, hose orientation (ifj).
• Figure 12 shows an example of offloading load cases within the extended offloading zone 25, where the emergency load case applied as ULS in a first zone 302 immediately behind the central portion of the offloading zone 25 provides perceived risks of drift-off and reverse drift-off.
• Emergency load cases applied as ALS in a second zone 304 provides the perceived risks of drift-off with reduced probability of disconnection failure.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Rigid Pipes And Flexible Pipes (AREA)
• Earth Drilling (AREA)

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Citations (6)

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• 2014
  • 2014-06-10 GB GB1410310.5A patent/GB2527071A/en not_active Withdrawn
• 2015
  • 2015-06-08 EP EP15728125.4A patent/EP3154852B1/de active Active
  • 2015-06-08 WO PCT/GB2015/051663 patent/WO2015189580A1/en active Application Filing

Patent Citations (6)

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