monopile gripper arms (mga) - houlder ltd · monopile gripper arms (mga) fixing the position of the...
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Application
+ Construction of Offshore Wind Farms (OWFs) – Monopile Foundations Installation
monopile gripper Arms (mgA) Fixing the position of the monopiles during lowering to the seabed for stability and safety
The Gripper Arms provide the horizontal restraint required to resist environmental forces acting on the large foundation piles during installation, providing a necessary support for efficient installation and to reduce safety hazards.
• Providethehorizontalrestraintrequiredtomaintainaccuracyandseepuppileinstallation
• Armsrequireminimaldeckspace.Theyaremechanicallystowed“latched”atmaindecklevel.
• Inherentlysafewithfailsafehydraulicsandredundancy
• Singleconsoleondecklocatedonthedeckforefficiency
benefits relevAnt codes, stAndArds & legislAtion
TheMonopileGripperArmsystemcomplieswiththerequirementsof:
• DNV-OS-C101-DesignofSteelStructures,General,LRFDMethod,April2011
Alloperationsshallbeengineeredinaccordancewiththemostrecentversionsof,orsimilarto:
• DesignaccordingtotheregulationsstatedintheEuropeanMachineryDirectiveRegulationsandderivedstandards(e.g.ENISO14122)
• NobleDentonGuidelines0030–GuidelinesfortheMarineTransportations
• DNVRulesforPlanningandExecutionofMarineOperations(DNV-OS-J101)
• DNV-GLGuidelines(DNVGL-ST-N001)
• ApplicableDanishLaw
• InternationalMaritimeOrganizationStandards&Guidelines
• SOLAS&MARPOL
Houlderhasoneunitavailableforhire.
hire options
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design pArAmeters
Themaindesignparametersarepresentedbelow:
MainDesignParameters
Monopilemaxdiameter 7.5m
operAting conditions
Themainoperatingconditionsarelistedbelow:
MainOperatingConditions
Significantwaveheight 2m
Maxcurrent 3knots
Conditionsvarywithpilediameter.Smallerpilesmay
havehigherlimits.
system specificAtion
Inrecognitionofthesystemrequirementsandinresponsetogeneralrequirements,themaindesignspecificationsarelistedbelow:
• Tobefittedonthedeckofanominatedconstructionvesselinalocationwithsufficientspacetomaximisethecapacityofthemaincrane
• Shallprovidelateralstabilityandrestraintomonopiles
• Maximumpermissibleloadduringtheinstallationofpilesisapproximately150tsideload
• ShallbedesignedtowithstandallforcesimposedduringthepositioningofmonopilestakingintoaccountallnecessaryDAFfactorsandthepotentialloadsimposedbypileoscillationsduringinstallation
• Thesystemshallprovideadequatelateraladjustabilitytoensurethepileisinstalledwithinaverticaltoleranceof+/-0.25º
• Toleranceforpositioningradiallyinplanfromconsentedlocationtobe+/-1.5m
• Tobedesignedsuchthatitissafeasisreasonablypracticableanddoesnotpresentasignificantrisktohealthorenvironment
• CanbeintegratedwithHoulderUpendingFrame
• GripperArmallowshammersleevetopassduringpilingbyopeningofjaws
• Equipmenttoincludesafeandeasyaccessstructuresparticularlyonthearms
• Maintenancefriendly
technicAl detAils
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system components
Thefollowinglistgivesanindicationofthemainitemsandcomponentsthatmakeupthegrippersystem.
SystemComponents
Jawassembly(x2)
Innerarmassembly(x2)
Outerarmassembly(x2)
Hingeassembly(x2)
Outercylinder(x2)
Innercylinder(x2)
Liftingcylinder(x2)
Liftinglinkassembly(x2)
Liftingframeassembly(x2)
Deckframeassembly(x2)
Grillage
HydraulicPowerUnit(HPU)
hpU
Theequipmentispoweredbyatwin110kwHydraulicpowerthatiselectricallydriven,openframeanddeckmounted.TheHPUissuppliedwitha2000ltrstainlesssteeltank.TheoptimalpositionfortheHPUisbetweenthetwodeckframesasshowninFigure3howeveritwillrequirerepositioningforthisspecificprojectduetothelocationoftheUpendingHinge.Theequipmentrequiresthefollowingpowersupplywhichisexpectedtobederivedfromvesselpoweranddistributionsystem:
• 415/440v3ph
• 50/60HZ
• 200A
operAting procedUre & fUnction
Thefollowingoperationsaretypicallyundertakenduringmonopileinstallation:
• Thewindfarmconstructionvessel(loadedwithpiles)ispositionedoverreferencetargetatpre-definedorientation.(Orientationcandependoncableroutes,currentandweatherdataetc.)Vesselisjackedtoworkingheight
• Thegripperarmsareloweredtothehorizontalposition,onearmatatime.Botharmswillbeattheirmaximumopeningwithbothoutercylindersfullyretracted
• Thegripperarmsareextendedattheirmid-strokepositionandarekeptopened
• Thepileisupendedfromhorizontaltoverticalusinginstallationvesselcraneanddecktools
• Cranemovesthepiletothepre-calculatedcraneradius(actualcentreofgripperradius).Thisradiusvariesaccordingtopilediameter
• Craneslewsuntilcentreofpilemeetsthecentrelineofgripperarms
• Thepileisloweredthroughtheopenpilegripper.Pileiskeptoutofthewater
• Thepileorientationisverifiedandpilemayberotatedasrequired
• Thepilegripperarmsareclosedaroundthepiletorestrainandguideitlaterally.Asmallgapismaintainedbetweenthegripperjawsandthepile
• Thepileisloweredthroughtheopenpilegripperuntiltheself-weightpenetratestheseabed
• Pileinclinationisverified(byhumanintervention)andadjustedbythegripperarmsifnecessarytobringthepiletothe‘truevertical’position
• Themaincraneisunlatchedfromthepile(viapileupendingandliftingtool)
• Themaincraneinstallsthedrivinghammerontothepiletop
• Pileinclinationisfrequentlyverified(byhumanintervention)beforeandbetweenthehammeringoperations(hammerblows).Theinclinationofthepileisadjustedbythegripperarmsifnecessarytomaintainitsverticalposition
• Thepileisdriventothepredetermineddepthwherethepilecanholditselfverticallywithouttheassistanceofthegripper.Thegripperarmsarethenfullyopenedtoallowclearanceforthepilehammer
• Thepileisdriventothetargetdepth
• Thegripperisretractedandraisedpriortothe“TransitionPiece”installation
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trAining
Trainingcanbeprovidedtopersonnelnominatedbytheclient.Trainingshallcompriseofon-site,handsonsupervisoroperatorandmaintainertraining.Thiswillbespecifictotheequipmentsuppliedunderthisagreementandinstructionintheproceduresandroutinescontainedintheequipment’soperationsandmaintenancemanual.Theclientshallonlynominatepersonnelthatitconsiderstobecompetentandexperiencedgenerallywithintheirrespectiveroles,inoffshoreliftingandinstallationworks.
offshore sUpport
Houldercanmakeavailableoneoffshoretechnicianfamiliarwiththesystemoperationandtroubleshootingtosailwiththenominatedinstallationvesselonthefirstcycle.AlternativelyHouldercanprovideoffshoreoperationsforthefulloffshoreperiodtooperatethegripper.
mAintenAnce
HouldercancarryoutmaintenanceworkontheitemsofequipmentinaccordancetotheO&Mmanual.Clientmaycarryoutsuchworkusingpersonneltrainedtodoso.
vAriAtions
hoUlder mgA-01
HoulderprovidedthefirstMonopileGripperArmsystemtoMPIOffshorein2013whichisinstalledupontheirwindturbineinstallationvesseltheMPIDiscovery.TheequipmenthasaidedinstallationworksforvariouswindfarmprojectsincludingtheLondonArray,HumberGateway,AmrumbankWest&Rampionoffshorewindfarms.Thesystemiscurrentlyconfiguredtohandlepileswithamaximumdiameterof6.5m
hoUlder mgA-02
HoulderrecentlysuppliedasystemtoRampionOffshoreWindLtd(asubsidiarycompanyofE.ONClimate&Renewables)aspartofahireagreement.
ThesystemhasaidedthemonopileinstallationworksoftheRampionOffshoreWindfarmandwasdemobilisedfromSwireBlueOcean’sPacificOrcaduringNovember2016.
Theequipmentdiffersfromtheoriginaldesignduetotheincorporationofamodulargrillagewhichenablesthesystemtobeconnectedtothevesseldeckwithnoattachmenttothetransom.Thisallowstheequipmenttobemobilisedanddemobilisedfromvesseltovessel.
7.5m JAw
Theexistinggripper’sjawconfigurationcanbemodifiedtosuitamaximumpilediameterof7.5m.
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Houlder is an independent, innovative offshore engineering company. We build on 30 years’ offshore expertise and work closely with clients to design solutions for their technical challenges. We provide complete EPCI services with special equipment, consultancy, project management and engineering solutions for the offshore wind and wider energy sector.