SHIP/SHORE LNG TRANSFER : HOW TO CUT COST ? SHIP/SHORE … Conferences/2000/Dat… · SHIP/SHORE LNG TRANSFER : HOW TO CUT COST ? PAGE 6 technical room. All ship/shore interface electronic

SHIP/SHORE LNG TRANSFER : HOW TO CUT COST ?

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SHIP/SHORE LNG TRANSFER˚: HOW TO CUT COST˚?

by

Bernard DUPONT EURODIM Sa,Michael OFFREDI ITP Interpipe,

Emmanuel FLESCH GAZ DE FRANCEChris THOMAS and Bertrand LANQUETIN TOTALFINAELF

Abstract :

THIS PAPER WILL FIRST REVIEW THE EXISTING LNG TRANSFER SHIP/SHORESYSTEMS AND THE TYPICAL COST OF THESE FACILITIES.

SIGNIFICANT NOVEL IDEAS TO REDUCE THE COST OF THE TRANSFER FACILITIESWILL BE REVIEWED.

A NEW DESIGN OF MARINE TERMINAL, CURRENTLY UNDERTAKEN BY A GROUP OFFRENCH COMPANIES SET UP BY GAZ DE FRANCE AND TOTALFINAELF, WILL BEUNVEILED :

- THE TRANSFER LINES ON A COSTLY TRESTLE ARE REPLACED BY NEWCRYOGENIC SUBSEA PIPES DEVELOPED BY ITP INTERPIPE APPLYING PATENTEDTECHNOLOGY FROM HP/HT SEA LINE

- A NEW CONCEPT OF LOADING PLATFORM AND TRANSFER SYSTEM, LINKINGSUBMERGED LINE TO LNG CARRIER IS DEVELOPED BY EURODIM, TAKINGADVANTAGE, INTER ALIA, OF THE EMERGENCE ON THE MARKET OF RELIABLECRYOGENIC FLEXIBLE LINES AS AN ALTERNATIVE TO CONVENTIONAL LOADINGARMS.

OPERATIONAL AND SAFETY ASPECTS OF THE NEW SYSTEMS WILL BE DEVELOPEDAND TYPICAL COST ELEMENTS ESTABLISHED.

FINALLY, THE PROPOSED PLANS FOR FULL VALIDATION OF THE NOVEL LNGTRANSFER FACILITIES WILL BE PRESENTED.


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TABLE OF CONTENTS

1 - SUMMARY

2 - EXISTING LNG TRANSFER FACILITIES

2-1 RECEIVING TERMINAL2-2 LOADING FACILITIES2-3 TYPICAL COST ELEMENTS

3 - REVIEW OF UNCONVENTIONAL SCHEMES

3-1 SUBSEA CRYOGENIC PIPE3-2 TRANSFER SYSTEMS

4- NEW LNG TRANSFER CONCEPTS

4-1 DOUBLE WALL PIPE

OBJECTIVES OF THE SUBSEA CRYOGENIC PIPELINECONCEPT DEFINITIONCOMPONENTS OF CRYOGENIC PIPEDESIGN PHILOSOPHYFABRICATION & INSTALLATIONPRECOMMISSIONINGSAFETYREPAIRCOST ELEMENTSON GOING QUALIFICATION PROGRAMME

4-2 TRANSFER SYSTEM ARCHITECTURE

CONCEPT DEFINITIONDESCRIPTION OF THE COMPONENTSDESIGN CRITERIA AND RESULTSCONNECTING MODULESAFETY AND OPERATIONCOST ELEMENTSFUTURE DEVELOPMENT


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5- CHALLENGES

5-1 CONSERVATISM OF LNG BUSINESS5-2 TARGET FOR COST REDUCTION5-3 REGULATORY ASPECT

6- WAY FORWARD

6-1 OVERALL SAFETY ASPECT6-2 PIPE IN PIPE SPOOL AND CRYOGENIC TEST6-3 CONNECTING MODULE


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1 -SUMMARY

The existing LNG transfer facilities are robust and safe; over the years the safety level of loadingarms have improved but the weight and the associated cost of the jetty head facilities have increasedas well.

New receiving terminals in emerging countries have to face challenging marine conditions withmonsoon season and no natural harbour. Revamping of existing facilities is often difficult becauseof poor access to new larger ships.

Existing LNG transfer facilities were designed for a high gas commodity price; emerging marketwill offer lower price for gas hence the whole LNG chain cost must be reduced including thetransfer facilities.

The architecture developed by EURODIM offers a more compliant transfer system based oncryogenic flexible available today; present development focuses on the load filtering and theconnection of the flexible to the ship manifold. EURODIM is also working on an open sea transfersystem with significant wave height up to 3.5 m.

Replacing costly trestle system by sub-sea pipe will globally reduce the cost of the LNG transferfacilities. The cryogenic insulated Pipe developed by ITP Interpipe is based on proven weldabilityof Invar pipe, Izoflex unique heat insulating characteristics as well as the proven double wall pipetechnology developed for TOTAL by ITP Interpipe (Dunbar , 1992) and then extended to furtherprojects such as HP/HT SHELL ETAP or ELF TCHIBELI. Feasibility studies have confirmed thatthere are neither mechanical nor thermal limitations to the concept and a series of cryogenic tests ona representative spool of Double Wall Pipe will be launched shortly at Gaz de France testingfacilities.

Full validation of both concepts will require more development work to be carried out within aproject framework

Irrespective of the unmatched quality of these two novel technologies, the project team will have toconvince the LNG community that both concepts are safe and attractive. This may take longer thanexpected and this paper is the first step toward this goal.


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2 - EXISTING LNG TRANSFER FACILITIES

LNG transfer facilities are as old as the LNG business with currently some 15 LNG Plants and circa38 receiving terminals in operation; around 70 LNG transfer facilities are in service world-wide andthis number is expected to grow yearly by a couple of units.

Except for two receiving terminals (COVE POINT in the US and the new OGISHIMA terminal inJAPAN) the transfer arms are linked to the shore by a trestle or a causeway.The storage tanks and the transfer facilities for Cove Point and new OGISHIMA are connected viaan underground tunnel.

We will give a brief description of the conventional transfer systems, which comprises two distinctsub-systems:

- The transfer arms and ship berthing and mooring facilities- The connection between the tank farm and the jetty head

The following captures the main functionality of the two sub-systems.

2.1 RECEIVING TERMINAL

The transfer facilities usually feature :

- A jetty head with berthing and mooring dolphins associated to a platform equipped with gangwayand loading arms; several process items are also located on this platform (filters, manifolds, draindrum ). Fire protection equipment (foam, dry powder and firewater) provides adequate safetycoverage. A control booth overlooks the transfer platform. Additionally utilities can be provided tothe Ship.

- Dolphins : 4 berthing dolphins and 6 mooring dolphins are usually required; all the mooringarrangement is designed in accordance with the acceptable drift of the Loading Arms (usually 3.5 mfore/aft).

- Loading arms (2 to 4 liquids and 1 vapour) are required to unload the gas carrier at a rate between3000 to 12000 m3/h. The size of the loading arms are typically 12/16 inch. Most of the loadingarms are fitted with an Emergency Disconnection system.It should be noted that over time the sophistication of the transfer arms has increased and the safetylevel has steadily improved with only a few serious incidents to report.

- The unloading facilities are equipped with filters to avoid contamination of the storage tanks byundesirable material. All transfer equipment can be drained into a vessel where LNG is eithervented or pumped back to the unloading lines.

- Fire fighting systems include high expansion foam monitors over a spill basin which recoversLNG spillage; dry powder fire extinguishers and fire water monitors complement the fire protectionhardware.

- Monitoring of the ship berthing and operation of gangway and loading arms is done from a


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technical room. All ship/shore interface electronic equipment is located in this building.

- Nitrogen or inert gas is required for commissioning and decommissioning of the loading arms.Additional utilities can be provided by the shore to the ship such as bunker, diesel oil, fresh water,liquid nitrogen

- A connecting trestle (or causeway) supports all necessary pipes (process and utilities) along withelectric and instrument cables. The trestle supports also a maintenance road. The average lengthbetween the storage area and the transfer facilities for the receiving terminals is around 500 metersbut can be much longer when no natural harbour is available.

- Process pipes

The size of unloading pipes is around 24/30 inches to match the LNG carrier cargo pumphead ,the elevation of the Storage Tanks and the design flowrate set by the duration of theunloading operation.Usually two pipes of the same size are used in parallel during unloading operation and inseries to keep the pipe cold in holding mode.The Vapour displaced in the shore tanks can be returned to the ship by a dedicated line.

- Utilities Pipes

Firewater, nitrogen, compressed air complemented by bunker, diesel oil, and fresh water asrequired.

- Maintenance Road

This maintenance road is designed to carry fire truck and maintenance crane necessary toservice the loading arms and other equipment.


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2.2 LNG PLANT LOADING FACILITIES

The description of the LNG loading facilities is very much the same as the unloading facilitiesdescribed above.The platform accommodates larger drain drum designed for the surge protection of equipment at theJetty Head.

The longest connection between the tank farm and the jetty head is around 6 km for the LNG Plant.Because the relative cost of marine facilities is lower for the LNG Plant than for a LNG receivingterminal, the siteing of LNG plant doesn t always minimise the cost of the transfer facilities.Unlike the receiving terminals the vapour displaced during loading operation is often flared due tojetty length and poor economic incentive to recover marginal flared gas.Figure 2.2 pictures an artistic view of BONTANG 3rd dock.

Figure 2.2 BONTANG 3rd LNG/LPG DOCK


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2.3 TYPICAL COST ELEMENTS

Although there are differences from one project to another in terms of sizing and cost of LNGtransfer facilities, our project has retained the following estimation for reference:

ESTIMATE($/99)

Berthing andmooring

15 M$

Jetty head 20 M$Trestle 15 M$/1000

meterPipes/ cables 13 M$/1000

meter

The above in-house estimates for overall project are based on typical productivity and manpowerrates for emerging countries.

3 - REVIEW OF UNCONVENTIONAL SCHEMES

3.1 SUB SEA CRYOGENIC PIPE

Sub-sea cryogenic pipe is not in itself a novel idea; but the current project applies un-common newdesign features.Since the very early days of the LNG industry, cryogenic pipelines have been one of the subject ofchoice in world wide conference [1][2][3][4][5]. Subsea cryogenic pipelines have been alsodescribed in some details [6],[7],[10].

The main problems associated with submarine cryogenic pipes are :

- material of construction should be resistant to low temperature;- shrinkage of the pipe should be accommodated;- insulation system highly effective thermally, water tight and strong to permit handling;- fail-safe system i.e. the line should remain operational in case of local damage.

Several solutions have been proposed, out of which the most significant are:

- retrained / pre-strained double pipe system [6] recommending the fabrication of pre-strainedsection of pipe with the limit of non-uniform prestrain along the length of the pipe. SHELL tested atcryogenic temperature sections of pre-strained pipe.

- Modular sections [7] wherein multiple LNG pipe sections utilising expansion joints tocompensate for contraction are connected together by braces to form an integral frame, includingpressure vessels enclosing the expansion joints to permit access for inspection and maintenance .Patent drawing is shown below (figure 3.1) :

- Concentrical LNG pipe-in pipe with a main transfer conduit and a return conduit both positionedwithin an outer jacket [10].


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Figure 3.1 US PATENT 4,826,354 general principle

None of these systems have been applied in projects.

Among current development effort, a company proposing a Poly Urethane Light Foam Systemhave been working for some time on a cryogenic pipeline that could well be used offshore. Full-scale cycle test at cryogenic temperature have been successfully conducted by this company.

The patented novel cryogenic sub-marine pipe as developed by ITP InTerPipe differs from theabove systems by the following features:

- Double Wall Pipe technology currently used on sub-sea HP/HT projects.- Internal pipe in INVAR with no loops or expansion joints.- Best insulating material IZOFLEX thus reducing the size of the external pipe.- Continuous annular.- External pipe to handle massive external aggression.


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3.2 LNG TRANSFER SYSTEMS

A number of R&D programs have been launched to develop un-conventional LNG transfer system.In the past, TOTAL has been associated in the CHAGAL program [8]. This project was based onthe development of a cryogenic Single Point Mooring, which required sub-sea flow lines andPLEM, flexible hoses and a cryogenic swivel to be designed and tested.8 cryogenic flexible was designed and tested by COFLEXIP. Patents for the cryogenic 16-inchswivel initiated by EMH were taken over by SBM. As yet, no LNG transfer project has been basedon this concept.More recently however, COFLEXIP STENA OFFSHORE has promoted a JIP for the developmentof a 16 NPS cryogenic flexible to be used for offshore LNG transfer.

Offshore LNG transfer has prompted also extensive R&D programs by FMC (Boom To Tanker),SBM (single offloading arm) and STATOIL(Offshore Cryogenic Loading System).

While offshore development of LNG Plant on barge or FPSO remains still prospective, severalLNG terminals in emerging countries are at various design stages and are expected to come tofruition in the near future, probably sooner than LNG offshore transfer from FPSO to LNG carrier.Hence the approach of our group to appraise if technology developed for the far future (in our caselarge cryogenic flexible) could be used to reduce the cost of our current projects.

The architecture as developed by EURODIM is based on existing cryogenic flexibles already testedor being tested by the industry.


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4- NEW LNG TRANSFER CONCEPTS

Although the novel systems presented in this paper could apply to both export terminals andreceiving terminals, our effort has focused more on receiving terminal because there are currentlymore receiving terminals at project phases within the portfolios of the sponsors of this researchprogram.Our work has been based on a receiving terminal without vapor return for sake of simplicity. Itshould be noted that a vapor return line could be added using the same concepts ;moreoverunloading an LNG carrier without vapor return has been safely achieved in the past and wouldrequire only minor modification to existing LNG carriers re-gasification facilities.

4.1 DOUBLE WALL PIPE

4.1.1 OBJECTIVES OF THE SUBSEA CRYOGENIC PIPELINE

The sub-sea cryogenic pipeline provides the LNG connection between the offloading platform andthe onshore storage facility.

The main criteria that led to the final design for this sub-sea system are the following :

- cost reduction. Operators shall consider the new architecture of interest only if significant costsavings are associated with it by comparison with the conventional scheme.

- Simple and robust design. With respect to operators requirements, the selected design mustavoid as much as possible complex devices or high technology components which increase theOPEX (maintenance costs) and the risk of failure of the system. Concepts such as underwatertunnels or sub-sea expansion loops/ expansion joints were not considered.

- High thermal performances. Due to the length of line targeted by the project (more than 1mile; typically 3 miles), the heat transfers between the transport pipe and sea environment have tobe reduced as much as possible. The thermal performances of ITP insulated systems with IZOFLEXmaterial were recently confirmed by full scale thermal tests carried out in Houston by a JIP led byTEXACO associated with BPAmoco, ExxonMobil and TotalFinaElf.

- Reliability and safety of the system, during installation and in operation.

4-1-2 CONCEPT DEFINITION

To meet the various requirements listed above, the project team selected a design based on theDouble Wall Pipe technology developed by ITP InTerPipe and already in operation for thetransportation of hot effluent.

ITP double wall pipeline technology consists of two coaxial pipes: an inner pipe is inserted withinan outer pipe and both pipes are linked at their ends. The sealed annular space between the pipesallows to implement high performance insulation material that reduce significantly the heat transferbetween inner pipe, containing LNG and outer pipe in contact with the seawater.


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The ITP system provides the following main benefits to the project:

- Capex and Opex reduction;- Safe and simple design for a reduced failure risk;- Environmental friendliness (sub-sea installation);- High insulation capacity to reduce heat ingress.

4-1-3 COMPONENTS OF CRYOGENIC PIPE

The double wall pipe developed by ITP includes:

- Inner pipe The inner pipe is made of a Nickel alloy with 36% of Ni, commercially named INVAR or Pernifer36. Because of its very low expansion coefficient, the thermal stresses and strains resulting from thetemperature difference are maintained low (approx. 10 times smaller than stainless steel material).Combined with its high mechanical strength, high tenacity and good welding properties, theINVAR material simplifies the design and fabrication of the system. Indeed, there is no need ofartificial expansion device due to the thermal or mechanical length variation. - Insulation material : IZOFLEX The selected insulation is the Izoflex, a material developed, patented by ITP and alreadyimplemented to insulate several hot effluent pipeline including pipe with significant temperaturedifference between transported multiphase product and outside environment.

TYPICAL CRYOGENIC DOUBLE WALL PIPELINE

CONCRETELAYER

OUTER PIPE :CARBON STEEL

48 /20.6 mm

IZOFLEXTM

INSULATION 100 MM

INNER PIPE :INVAR

36 / 6 MM


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The high thermal insulation properties of the IZOFLEX enables to design a high thermalperformance double wall pipeline within a reduced annular. The thickness of IZOFLEX to be usedis four times smaller than the one that would have been necessary with Poly Isocyanate Resin (PIR)insulation for equivalent thermal performances. The resulting compact system contributes to costssavings. Mechanical testing in cryogenic environment carried out during the design phase of the projectconfirmed the suitability of the material for LNG transport application. The good mechanical behaviour at any temperature combined with a limited shrinkage effect at lowtemperatures and a good annular filling ensures the concentricity of the inner and outer pipes. Noannular spacers are required. Due to the fabrication procedure and insulation material installationprocess, thermal-bridging effect along the overall pipeline is reduced to a minimum and overallthermal performance is optimised. - Outer pipeThe outer pipe is made of regular carbon steel. This material is designed to protect the internal pipe& the insulation system. The high weight increases the sub-sea stability of the line. The low cost ofthe material contributes to the Capex reduction.

- ConcreteA concrete layer is added for additional protection and pipe stability.


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4-1-4 DESIGN PHILOSOPHY

The pipe system has been designed to withstand:

- the loads induced by the installation process (string weight and associated tension, hydrostaticpressure, temperature variations );

- the loads in operation (thermal loads, internal and external pressures and differential pressures,seabed stability, fatigue ) during the life of the pipe.

These various criteria have been reviewed in accordance with the main codes and standards forrefrigeration and sub-sea pipelines. Basically, the inner pipe and the insulation material reduce theimpact of the temperature variations and the outer pipe ensures the integrity of the system. Thecontinuous annulus all the way through the line allows the placement of additional control devices.Pressure and temperature control gauges and secondary annular protection increase the safety of thesystem and allow the operator to control the system at any time.

4-1-5 FABRICATION & INSTALLATION A specific fabrication process has been developed for the cryogenic double wall pipeline. Thissequence is driven by the installation procedure based on the towing method. The fabrication sequence is divided into several fabrication steps. A first step is the pre-assembly ofinsulated units (6 or 12 meters long). These pieces are welded together to produce 250 m longstrings or longer. Once the strings are ready, they are welded onshore before being pulled by suitably adapted meansup to the appropriate location. A double wall insulated riser provides the connection between thesub-sea pipe and the offloading platform at one end. At the other end, an onshore connecting pipewill be tied up to the manifold of the storage tanks. Up to 5000-m long double wall pipeline lay boats or heavy lift crane barge (bottom towing method)might pull system from the shore to its final position on the seabed. 4-1-6 PRECOMMISSIONING In order to control the mechanical integrity of the Double Wall Pipe strings, pneumatic testing iscarried out on welded strings before starting the installation.


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4-1-7 SAFETY Safety issues, as for every new LNG technology, have been particularly addressed. The majorsafety issues for the sub-sea cryogenic double wall pipeline are related to a failure of thecontainment systems. - Water ingress (failure of external pipe): The risk of occurrence of such an event is reduced to an acceptable level, thanks to proper design ofthe pipe external protection (trenching, concrete protection). Water ingress is monitored by continuous analysis of the annular space normally operating underreduced pressure; in case of external pipe failure, a large water ingress can be prevented bypressurisation of the annular space with air. - LNG egress (failure of the internal pipe): Similarly LNG leaks will be detectable by continuous monitoring of the temperature in the annularspace and minor leaks can be reduced by back pressurisation of the annular space by fuel gas whilethe system is safely decommissioned for repair. 4-1-8 REPAIR

Various scenarii are considered for repair in case of accidental pipe failure:- Sub-sea repair, in dry atmosphere in shallow water depth- Surface repair after pipe recovery by a lifting barge when a section of the pipe needs replacement.Repair procedure takes into account the corrosive behaviour of sea water on Invar piping.

4-1-9 COST ELEMENTS For a 2 x 36 inch, our internal evaluation is around 13 000 $/m as direct cost and around 8500 $/mfor a 2 x 30 inch configuration. 4-1-10 ON GOING QUALIFICATION PROGRAMME

The next step of our development program is the fabrication and testing of a full-scale double wallpipeline sample. The scope of work includes notably the review of the fabrication process, analysisof component behaviour during LNG circulation, confirmation of the thermal performances of thesystem.Testing will be done at Gaz de France cryogenic premises at NANTES.


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4-2 TRANSFER SYSTEM ARCHITECTURE

4-2-1 CONCEPT DEFINITION

The architecture and system proposed by EURODIM is based on an equipment that has beensuccessfully tested or are currently being tested such as cryogenic flexibles lines from M/SCOFLEXIP or M/S COMPOFLEX.The flexibles lines with their supporting infrastructure are significantly lighter as compared totraditional articulated arms.Additionally maintenance of the flexibles and other process items doesn t require a large crane.Both aspects reduce the overall dimensions and the cost of the transfer facilities.

4-2-2 DESCRIPTION OF THE COMPONENTS

The transfer facilities main components are:

- A two level platform with a technical room, a drain drum, compressed air and nitrogen reserves anda boat landing with utilities connections at the cellar deck; On the main deck, manifolds, filters andpipes connecting the cryogenic sealines to the flexibles.

- A structure supporting in stand-by mode all the flexibles lines and the associated connectingmodules stored separately; a light lifting crane is designed to handle efficiently all connectors andflexible lines.

- Gangway and fire water monitors are located on the same structures- Typical berthing and mooring dolphins as required for the traditional transfer facilities- Firewater connections are located on the closest mooring dolphins.

Figure 4.2.1 pictures a simplified view of the new transfer system for a Receiving Terminal.


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FIG. 4.2.1 NOVEL TRANSFER SYSTEM ARTISTIC VIEW

4-2-3 DESIGN CRITERIA AND RESULTS

For the LNG transfer system and architecture, our group has focused on a Receiving Terminal forstandard LNG carriers ranging from 70 000 m3 to 135 000 m3.

The LNG unloading rate considered is 10 000 m3/hour.

As for the present terminals, the berthing site is considered as relatively sheltered (in the first phaseof development) and loading/mooring environment corresponds to significant wave heights of 1.5to 2 meters. In these conditions, the safe operating envelope of movements of the ship manifold axisduring loading is typically 11 meters fore/aft, 6 meters transversally and 8 meters vertically.

In order to achieve our objective to reduce cost while maintaining or even improving the safetylevel of the new transfer system, we have taken a very conservative stand for the workingconditions of the flexible lines.

The newly developed large size cryogenic flexible hoses coming to the market are somewhat’overdone’ for the present application — since they are designed and built to permit offshore LNGtransfer (from FPSO to LNG carrier) in sea states of some 5 meters significant wave.

Notably we have based the conceptual design and architecture on a minimal bending radius of 10


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meters for the catenary suspended cryogenic lines. The catenary suspension of the cryogenic hosehas been chosen because it is ideal in order to keep excellent internal working conditions in theflexible even in the case of large 3-D motions of the offshore transfer.

The flow rate of 10 000 m3/hour requires 3 x 16" diameter lines for a length of 45 meters each. Wehave developed a system able to cope with 3 to 4 x 16" diameter lines (possibility to include onespare flexible) or even with 20" diameter flexible lines, should it be interesting economically.

With regards to safety, the transfer system design also integrates the mandatory requirement of asafe and reliable emergency disconnection system for the LNG lines.

The reliability and simplicity of the system for normal operations such as connection/disconnectionand storage are also participating to the safety of the concept, for which user friendliness has been agoverning design factor.

This, combined with the very limited acceptable load on the flanges of the ship manifold, has led toa design based on a flexible line attached at one end to the fixed platform and on the other end on aMulti-function Cryogenic Connection Module (MCCM) , interfacing the ship manifold flange andflexible line mobile extremity, which serves all the complex functions of the transfer system.

4-2-4 CONNECTING MODULE

Thus, for each flexible, the Multi-function Cryogenic Connection Module (patent pending) has thefollowing functions:

- Normal connection (flexible hot);- Filtering of the stresses induced by the physical motions and the loads induced by the flexible

line at cryogenic temperature in order to cope with the limited stress permissible at the shipmanifold flanges;

- Normal disconnection (flexible cold);- Emergency closure of the valves;- Emergency disconnection of the flexible assembly from the ship manifold.

This conceptual approach concentrating all the complex mechanical functionalities of the transfersystem in a modular unit which can be loaded, with the system integrated crane, onto a supplyvessel for possible inspection/maintenance, is an additional attractive point serving reliability andconsequently system availability and safety. The flexible line, is nicely suspended in catenaryconfiguration out of reach of any ’aggression’ in all conditions, i.e. storage or fluid transfer and isnot very sensitive to wind loads.

Our analyses confirm that the new transfer system developed is technically feasible and economical.Notably loads and cyclic movements imposed to the flexible lines are acceptable for the variousexisting technologies of cryogenic flexible hoses (one manufacturer has confirmed in depth ouranalyses) and the loads induced by the flexible lines movements and loads are acceptable forstandard Emergency Release Couplers and/or Quick Connect Disconnect Couplers. Further, itshould be noted that thanks to the flexible lines configuration, sophisticated and costly LNG swiveljoints can be saved and the system is ideally pure and simple.


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4-2-5 SAFETY AND OPERATION

The main safety requirements of the new system are comparable to the safety requirement of thetraditional articulated arm as in fact in both cases the major risk occurrence is located in the area ofship manifold at the level of the connectors.

In addition, one should note the extreme ’comfort’ in which the flexible hoses are working thanks to:

a) Benign environment.

b) There is a great margin in the utilization ratio of the flexible lines as the maximum movementenvelope considered is based on acceptable cyclic loading criteria.

An accidental excursion out of the working envelope will not lead to an alteration of the flexiblehose (such as for instance the yield stress of the stainless steel liner). Only minor leakage can beexpected in case of major incident. Naturally available cascade margins of multiple layers flexiblepipe with regard to acceptable ship movement are an interesting feature of the solution.Further, all transfer flexible lines can be disconnected at once in case of emergency (in case of shipmovements risking to overstretch flexible lines).Commissioning and decommissioning of the flexibles will follow the standard practices outlined bythe SIGTTO for the articulated arm; in particular, the flexibles shall be self-drainable and shall beinerted. Cool-down procedures relevant for cryogenic flexible lines shall be developed.

Between two consecutive cargo transfer, all operations to achieve the optimum readiness for thenext loading (basic maintenance and supply of utilities) will be done with a support vessel berthedat the main transfer platform.During LNG transfer operation, the supply vessel will be moored at a mooring dolphin for firewater supply and readiness to evacuate personnel in case of emergency.

Major maintenance activities such as replacement of flexible will be done by simple winching andonly a basic working barge or supply vessel is required for these operations.

In terms of operation, the proposed facilities have the same functionality that the base case; in ourestimation of the OPEX, we have included an additional supply boat, a contract for diving serviceson subsea lines and regular replacement for re-certification of the transfer flexibles.

As for the Safety aspect, all the criteria of traditional transfer facilities are met or exceeded.

4-2-6 COST ELEMENTS

Cost reduction for the transfer facilities have been estimated at some 5 M$ in terms of direct cost.The lower cost of the flexibles versus articulated arms and the simpler transfer platform bothparticipate equally to this cost reduction.Further studies on the simplification of the berthing and mooring pattern to fully use all thepotential of the flexibles in terms of drifting should further reduce the cost of the transfer facility.


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4-2-7 FUTURE DEVELOPMENT

The current efforts to develop this novel transfer system focus on:

- finalisation of the MCCM and industrialisation with manufacturers of cryogenic equipment;- modification of the berthing pattern in order to fully utilise the potential of the flexibles with a

direct objective to reduce the cost associated with the dolphin arrangement in a traditionalterminal;

- research and screening of more compliant transfer systems to match near shore open seaconditions up to Hs = 3,5 m (see fig 4.2.7).

Fig 4.2.7 COMPLIANT LNG LOADING SYSTEM


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5- CHALLENGES

5.1 CONSERVATISM OF LNG BUSINESS

Traditionally, the LNG business has been very conservative but, by the end of the last decade, noveldesigns have been applied to cope with the necessary cost reduction to increase LNG market share.Introduction of large single shaft gas turbine driving refrigeration compressor can be regarded inmany respects as more challenging than a sub-marine cryogenic pipe and/or a transfer system basedon cryogenic flexibles.Constant pressure for cost reduction pushes all operators to select innovative design.

5.2 TARGET FOR COST REDUCTION and IMPACT ON THE LNG PRICE

Clearly for a grass roots LNG Plant, the target of cost reduction when applying both concepts wouldbe at best a couple of percent of the overall project cost. Cryogenic sub sea pipe offers a largechoice for the location of additional LNG berths in the case of expansion projects.For a receiving facility, the cost reduction can be in the range 10-15% of the project cost when abreakwater and/or major dredging is mandatory.Altogether, the cost reduction in terms of saleable LNG in the range of 3/5 cents/Mmbtu is modestbut more cost reduction can be expected if the siteing of the LNG receiving facilities is optimisedwith regards to the location of large existing consumers (reduced interconnecting cost to bring thegas to the market).

5.3 REGULATORY ASPECT

For the Double Wall Pipe, governmental agencies will challenge the safety aspect of the sub-seaLNG pipe and the effect of a plausible loss of containment. Specific programs to address this issueare currently under development.

For the transfer facilities, the use of flexible is not forbidden but their use is currently limited tovery specific applications such as emergency transfer of cryogenic cargo. Hoses have beentraditionally compared to articulated arms and papers presented at SIGTTO panel [9] haveadvocated that hose operations are less risky than hard-arms or at least not more risky.Indeed, the use of large bore hoses is limited because of the uneasy operation of the flexiblecompared to balanced hard arms. In our project, a specific architecture with manipulating crane willbe used for all the operation related to connection / disconnection.

Thus, the issues raised in the codes and procedures can be successfully addressed by our proposedsystem but full recognition of both novel concepts by regulatory/government agencies is expectedto require some time.

6- WAY FORWARD

In order to get wider acceptance, additional work is required.

6-1 OVERALL SAFETY ASPECT

Both concepts must be carefully designed and detailed Quantitative Risk Assessment study is pre-requisite prior to the full endorsement of the concepts by operators.


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6-2 DOUBLE WALL PIPE SPOOL AND CRYOGENIC TEST

A spool of Double Wall Pipe will be fabricated by ITP Interpipe and tested at GAZ de FRANCEcryogenic test premises; detailed procedures for fabrication and installation will also be developedto better assess the cost of installed pipe.

6-3 CONNECTING MODULE

A detailed design of the connecting module based on full scale simulation and typical lay-out ofLNG carriers manifolds will be carried out shortly. This will confirm the feasibility of theconnecting module for all operating scenarios.The partners with a specialised manufacturer will develop a detailed mechanical design for themodule and confirm cost estimation.

ACKNOWLEDGMENT : this project is partly funded by the French Ministry of Industry.

REFERENCES:

[1] LNG PIPELINES by P Herv Air Liquide LNG 1 1968 Paper 29b[2] LIQUEFIED NATURAL GAS MAINS by O Ivan TZOV LN2 1970 Paper 3.7[3] TECHNICAL FEASIBILITY AND COST OF LNG PIPES by TE Hoover LNG 2 1970 Paper 3.8[4] PIPELINE AND GAS JOURNAL , June 1975[5] LES PIPELINES CRYOGENIQUES by Mr Mialon PETROLE & TECHNIQUES May 1984[6] A SUBMARINE OFFSHORE LOADING LINE FOR LNG by CWN Veeling (SHELL) LNG 3

paper II-8 1972[7] US PATENT 4,826,354 dated May 2sd 1989 UNDERWATER CRYOGENIC PIPELINE SYSTEM

Inventor A Adorjan EXXON.[8] OFFSHORE LOADING SYSTEMS FOR LIQUEFIED GAS by P Branchereau EMH LNG 8 Paper

IV-7 1986.[9] HARD ARMS versus HOSES SIGTTO PANEL 29/07/93;[10] US PATENT 6,012,292 dated Jan,11,2000 by Alan SILVERMAN (MOBIL).

CONTACTS

For more details on the project, please contact :- double pipe wall for [email protected] transfer system : [email protected]

Documents

SHIP/SHORE LNG TRANSFER : HOW TO CUT COST ? SHIP/SHORE … Conferences/2000/Dat… · SHIP/SHORE LNG TRANSFER : HOW TO CUT COST ? PAGE 6 technical room. All ship/shore interface electronic