THE HEAVYLIFT ENGINEER

THE HEAVY L I F T ENG INE ER

SPRING 2021

...managing & delivering heavy lift projects

ISSUE: 05

FEATURE ARTICLES- DESIGNING QUAYS FOR HEAVY LIFT

AND PROJECT CARGO USE- DESIGN AND BUILD OF LIFT BEAMS

- AN INSIGHT INTO ANCHORSELECTION

- FACTORY ACCEPTANCE TESTING(FAT)

A PUBLICATION

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THE HEAVYLIFT ENGINEER ISSUE 05

EDITORIAL page 5

AN INSIGHT INTO ANCHOR SELECTION page 19

DESIGNING QUAYS FOR HEAVY LIFT AND PROJECT CARGO USE page 7

FACTORY ACCEPTANCE TESTING (THE GOOD, THE BAD AND THE UGLY) page 15

CONTENTS

DESIGN AND FABRICATION OF LIFT BEAMS. page 25

Heavy Lift Tip - Open Circuits and Pivot Points 2 / page 13

Heavy Lift Tip - Choosing the Correct Anchor / page 23

Book Recommendations / page 18

Heavy Lift Tip - Configurations Tips in Solidworks / page 33

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EDITORIAL

Welcome to our spring edition of theHeavylift Engineer. This is our fifth edition,and you can find all previous issues todownload on our website as well as beingable to sign up to be notified as soon as neweditions become available for downloading.(www.heavyliftengineer.com/magazine).

It has been great to hear all of yourresponses and feedback to date and I lookforward to your views on our latest edition.

The past year has been a real struggle for usall, both professionally and personally.Across the country many have balancedhome and work responsibilities, whilstothers have had to keep themselves busywhilst on furlough - tough times for all. Witha vaccine now being rolled out, andpathways in place, we can all now moveforward together. Reflecting on my owntime in lockdown, whilst at times trying, ithas also highlighted new ways of working,and reminded me of my love of learningnew skills and sharing knowledge across theindustry and beyond.

This edition aims to share knowledge acrossa range of heavy lift areas, from an overviewof factory acceptance testing (FAT) and ofanchor selection, to an interesting piecepondering quayside design for heavy lift andproject cargo scopes. This is teamed with apiece outlining the considerations whendesigning lifting beams.

We have a selection of our helpful heavy lifttips, covering everything from Solidworks toopen circuits and pivot points – and of courseour book reviews, to offer some helpfulrecommendations for your next read.

Whether you are in shipbuilding, heavyfabrication, power generation or mining, theheavy lift engineer’s skill set is critical. Noother engineering discipline, if you decide todive deep enough, offers such a range oftechnical challenges. We hope that thisedition reflects that variety, offeringsomething of interest to you, regardless ofyour background.

Please do get in touch if you have a topic youwould like to see covered or would like toguest feature for a future release – and Ihope you enjoy this new edition!

We would love to hear from you! Pleasesend any questions to:[email protected]

Please also sign up for future editions at:www.heavyliftengineer.com

JOHN MACSWEEN, MANAGING DIRECTOR AT MALIN GROUP

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DESIGNING QUAYS FOR HEAVYLIFT AND PROJECT CARGO USE

A fundamental, yet often overlooked, aspectof heavy lift projects is the quaysideinfrastructure itself; it acts as an interfacebetween the land based operations andseagoing vessels for onward transport.

Quayside infrastructure comes in manyforms, whether aged, modern, purpose-builtor temporary and each have challenges inaccommodating specialised cargo transfersbetween land and vessel.

This article will focus on easily implementedfeatures for new quays, designed specificallywith heavy lift operations in mind and willprovide some high level considerations fordesigners of such facilities. It is worthstressing that this has not been written by acivil engineer, but rather by a regular user ofquay side facilities for, what is often, veryspecialist operations.

Therefore this article will not look at designmethods of such facilities but rather focus ondetails that, if incorporated, may makespecialist heavy lift operations much easier.They may also realise significant through lifeoperational cost savings which are far inexcess of the cost of incorporation at theoutset.

To understand quay requirements for heavylift projects, it is first important to consider thethree main methods of cargo transfer to andfrom a floating vessel. These are:

• by crane (Lift On/Lift Off – LoLo);• by trailer (Roll On/Roll Off – RoRo); or• by semi submerging alongside a quay to

float cargoes over the vessel (Float On/Float Off – FloFlo).

Each of these methods drives very specificdesign features that, if considered early, candramatically reduce operational costs ofcarrying out a heavy lift operation at a facility.

By crane – LOLO or cranes on quays

All mobile, and some fixed, cranes aregoverned by the fact that the heavier theload you want to lift and the further out youwant to lift it, the greater the reaction loadunder the outriggers and into the quay itself.

It is not unusual to find modern quaysides tohave designated “heavy lift pads” where thequay deck has been thickened, with largerpiles located in the area to allow for greaterconcentrated loads from a crane’s outriggers.

Comparing the outrigger spread from a rangeof modern large capacity cranes acrossmanufacturers we can see, as shown in figure1 (lifted from the relevant manufacturer’stechnical specifications) that, despite therange of manufacturers and lifting capacities,at this size of crane, the pad locations tend tobe very similar. This allows opportunities forthe design of the heavy lift pad on a quay tobe suitable for a wide range of cranes.

Designing a single, very specific, location forthe placement of a crane may restrict the useof that quay considerably. However, byrecognising these common centres andspacing them in accordance with a welldesigned and optimised pile arrangement,the best of both worlds may be achieved.

By trailer - RoRo or skidding overquays

For the load-out and load-in of heavycargoes, specialist trailers are employed,often in conjunction with temporary rampsanchored to the barge or floating vessel bymeans of an articulating hinge. This is shownin figure 2.

These ramps can apply some large edgeloadings to the quay surface and installationof embedded bearing strips can greatlyincrease the life of the quay surface. Anexample may be seen in figure 3.

With these temporary ramps installed to thebarge and bearing on the quay, the bargedeck must be above the quay level to allowa RoRo operation to proceed. This in turnreduces the cargo carrying capacity of thebarge and/or reduces the number ofuseable tides that any given operationrequires. An alternative to having the hingeplates mounted on the barge is to havethem mounted to a recess on the quayedge, as shown in figure 4, specially

designed for this purpose. This can reducerequired tide heights by between 300mmand 500mm, greatly increasing theuseability of a quay for high capacityloadouts.

fig. 1 / Comparison of outrigger sections of modern, large capacity mobile cranes

fig. 2 / Linkspan pieces being installed tobarge for loadout

fig. 3 / Embedded bearing bars on RoRoberth

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Quayside equipment and generalconsiderations

For typical heavylift operations, and specificallyRoRo or skidding operations, the arrangement ofquayside furniture and equipment is critical. Theplacement of bollards must consider the sweptpath of loadout operations so as to ensure thatthey do not clash with trailer or skidding lines.

Handrails should be removable and preferablyuse slotted posts flush with the quay deck ratherthan bolted ones. Services, service ducts andterminations as well as lighting should all bewell away from the quay edge anddemountable if they risk obstructing movementof an oversized load to and from the quay edge.

The quay deck should be flush to the quay edgewith no edging or kick plates/kerbs and shouldbe capable of taking high loadings right up to

the seaward edge. Loading out oversize cargoescan often require very long trains of heavytrailers or skidding tracks and gradients from thequay edge back into any hardstanding areabehind the quay should be minimised or,preferably, be negligible.

Mooring barges and dead vessels toquays

When mooring vessels alongside for heavyliftloadouts using floating or land based cranes,vessels will normally be moored in aconventional manner. In such circumstances,bollard positioning and capacities for anycommercial quay should be satisfactory.

When considering loadout situations, the loadson bollards and their positioning will be muchmore onerous and specialised. Figure 5 shows a

Written by John A. MacSween, Managing Director,Malin Group

deck cargo barge moored “stern to” a quay for theloading of a heavy cargo. As illustrated, these bargesare moored using winches with wire rope anchored tothe quayside. The means by which these arrangementscan be more easily implemented should beconsidered. This can involve:

• Bollard selection and design such that they permitapplication of force parallel to the quay edge.

• Bollards set off from quay edge to permit a winchto be adequately and safely sited.

• Bollards or anchor points located inland so thatredirecting sheaves are not required or theirrequirement is minimised.

• Panama fairleads or means of redirecting a wiremooring line to accommodate a range of bargetypes, capacities and positions relative to the quaydeck.

• Conduct a range of mooring analyses for typicalbarge sizes and windages to current heavyliftoperational guidelines to size the requiredcapacity of the bollards in question.

• Allow for the passage of wire ropes under tensionto an anchor point on the deck of thetransportation barge that may be under loadduring periods when the deck of the barge isbelow the quay level.

Rubbing strakes and fendering

When mooring barges to a quay for Ro Ro or skiddingoperations, the barge will usually be turned into aposition similar to that shown in Figure 5, at a pointwell before high water. During this period the mooringsystem will normally be pre-loaded and so the rubbingstrakes must be able to, as a minimum:

• Allow the barge transom to slide freely up anddown the rubbing strake.

• Be able to take high lateral loading into the quayface or seaward piles (see figure 6).

• Extend far enough down to ensure that at allstates of the tide, the barge cannot “slip” underthe fendering.

By semi-submersible - FloFlo or use of quay

We will close this article with a final note on keyconsiderations for operations that will require a bargeor vessel to submerge alongside a quay to float a cargoon or off. Many of the points above will still apply butspecial attention should be paid to the following:

• When submerging, many semi-submersiblevessels will touch the sea bed or come very closeto it, therefore the make-up of the bed around thequay should be well understood with no hardpoints which could impart high point loadings onthe submerging vessels hull.

• Rubbing fenders on the piles or quay face willneed to extend much deeper to account for thefact that the flat of vessel side will be considerablybelow the water line.

• Lead angles for mooring and/or winch lines willrun to the quay edge and then drop down to thetermination point on the semi-submersible deckand so the quay edge should have rubbing strakesor fairleads that permit this.

We hope that the article has provided a number ofpoints that may guide or inform your operations in thefuture. We would love to hear your feedback on theapplication of the points enumerated – or indeed anyadditional suggestions or notes of practice which wemay share in a subsequent article.

fig. 5 / Barge moored stern to quay for RoRo operation

fig. 4 / Linkspan hinge recess Vs linkspan hinge on the vessel itself

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fig. 6 / Barge loadings on fendering at low water

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Written by James Bowie, EngineeringDirector, Malin Abram

HEAVY LIFT TIPOPEN CIRCUITS AND PIVOT

POINTS 2

Previously we covered the topic of openHydraulic circuits. One of the basic issues/pitfalls involving self propelled modulartrailers (SPMTs) is unintended rotation aroundpivot points. We looked at the pivot pointcreated at the point of rotation of the axle.Now let us look at the other pivot points thatcan be created and the compounding effectthey could have on the system.

Looking further up from the trailer, we havepacking and then the interface with thecargo. Most cargo designers will insist on asingle, discrete loading point into thestructure, this is for the obvious issues ofsimplifying the design and analysis of thestructure. Unfortunately, as can be seen infigure 7, the single point of contact hasinadvertently created a narrow point ofcontact, which acts as a pivot point.Multiplying this to other points, means thatthe potential exists to create, in essence, apin jointed portal frame.

This is the obvious example. It can also occur,when it would appear that good load-bearinghas been achieved.

• If all the load-spreading supports are tiedinto a single support on the cargounderside, this can create a pivot point.

• If the cargo is a tubular construction andthe support is a saddle, there is thepossibility that the saddle can rotatearound the tubular.

Solutions to both of these examples arestrong shear stops (tubular) and lashings orsupport props to a different part of the cargo.

OPEN CIRCUITS AND PIVOTPOINTS 2

fig. 7 / Single point of contact

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FACTORYACCEPTANCETESTING

(THE GOOD, THEBAD AND THE UGLY)

fig. 8 / Archimedes Waveswingpre black build

Factory acceptance testing (FAT) is a criticalpart of any physical product realisation. Itshould be the opportunity to prove productperformance to the end client, is often asignificant payment milestone in the contractand is the last opportunity to fine tune theproduct in a controlled environment.

The reality however is often very differentand the FAT becomes the start of thebreakdown of the relationship betweensupplier and client, opening the door todebate, disagreement, formal dispute andfinancial consequences – why?

The discussion below is not intended as achecklist for undertaking a successful FATalthough many versions of such checklistsexist; rather it is intended to be more of adistillation of the lessons learned, both goodand bad, during a variety of such events in arange of industrial and commercial settings.

The good (often discussed, lessfrequently incorporated)

Experience indicates that a successful FAT isthe culmination of a process which starts withthe tender submission, continues through thedevelopment and manufacturing cycle andends with the client acceptance of theequipment and the approval to ship it to thejob site.

Key to this is the ability to understand anddefine what a successful FAT is for theequipment in question. Basically:

• Can the FAT replicate the full range ofoperation of the equipment i.e. is theequipment a stand-alone item or part oflarger system (which may or may not beavailable for the FAT).

• If a full functional test is not possible howare the inferred performance criteriadefined and accepted/rejected.

• What are the defined and agreedperformance criteria which can beundertaken during the FAT.

• How will they be measured.• Who will carry out these measurements

to ensure the results are accepted by allparties.

And…

• Who carries the cost of the FAT includingthe mobilisation & demobilisation of thesupporting equipment? This should beclarified as part of the contractnegotiations.

• Who pays for the cost of overruns in theFAT programme and any re-tests ifrequired.

• Who is responsible for equipmentdamage as a result of the testing, shouldthis occur.

Failure to tackle these questions in advancewill result in the FAT being no more than atest or tests carried out under the auspices ofbest endeavours, often witnessed by theclient and other interested parties.

The bad (well understood but oftenignored)

• The acceptance criteria have not beendefined in sufficient detail and areambiguous.

• The recorded results are disputed.• The FAT requires to be re-run and the

delivery milestone and associatedpayment is missed.

The ugly (seldom considered apossibility, usually results incontractual re-negotiation)

• No performance and thus test criteriahave been defined and are generatedduring the FAT.

• The equipment does not achieve thesegenerated test criteria.

• The equipment fails under test.• The client has the option to reject the

equipment or invoke a delay / discount/ damages clause in the contract.

Getting out of jail (or moreaccurately, not going to jail)

• Understand and agree the performancecriteria as early as possible andincorporate these into the contract.These effectively form a substantialportion of the design specification.

• If this is not possible, define at whichpoint in the development programme /project plan it will be possible to defineand agree these criteria.

• Define a mechanism for discussion,negotiation and arbitration should it berequired.

• Agree the costing mechanism and theimpact on the project plan timeline.

• Make this a progress stage gate andpayment milestone to ensure it is notbypassed in the rush to develop theproduct.

• Define how these criteria will beassessed, measured and recorded.Include feasible tolerances for criteriawhich are not yes / no.

• Define who will carry out thesemeasurements to ensure the results areaccepted by all parties.

Where do you fit?

You need to understand where you fit in thesupply chain, for example, is it a primarysupplier i.e. your customer is the end client,or are you a subcontractor? This has asignificant bearing on the level ofresponsibility carried during the FAT andprovides clarity on the information flow andpre-FAT testing required by you or for you.It is critical to understand theresponsibilities associated with theincorporation of pre-tested systems andsub-systems to the overall FAT. Examples ofthis include pipework pressure testing,electrical continuity checks etc. Clarificationof these cascaded sub-system tests shouldensure, as far as possible, that no potentialfor damage to the equipment exists duringthe FAT. This is not always feasible andwhere this is the case it is critical to defineany residual risks in advance of the FATcommencing. Responsibility for subsequentdamage due to untested sub-systemsshould also be clarified at this stage. Thisshould cover replacement of components,time and cost associated with delays and ifapplicable, financial damages.

Third party approvals

Although often not recognised as FAT’s, it isessential to understand the requirement forthird party testing and approval as these arein effect third party FAT’s which can havemuch more severe consequencesassociated with failure or sub optimalperformance. These often include CEMarking (if not conducted in-house andself-certified), EMC testing, testing andapproval under the pressure systemsregulations etc.

You need to be clear on the differentrequirements for stand-alone systems andthose incorporated into larger systems e.g.a stand-alone machining centre and apackaging machine, which is part of a high-speed production line.

These must be incorporated into the design,build and test schedules at the appropriatetimes to ensure that the completedequipment is fit for purpose, can be insuredand sold. These are often in addition to anythird-party approvals requested by theclient.

The Sequel - Site AcceptanceTesting (SAT)

So we have successfully completed the FATand the product has shipped to the client.Time to relax? No, it’s time to prepare for abigger challenge and one with many morevariables and significantly less control.

What’s different? Using a football analogy…

• If the equipment is stand-alone then itis a replay of the FAT at a differentground. If it is part of a larger systemthen it’s an away match so no hometeam advantage this time.

• Different crowd, bigger and possibly alittle more hostile.

• Know where the edges of the pitch arei.e. the boundary conditions.

• You are in the premier league now; therewards are bigger, the final milestonepayment.

• Failure to qualify at this stage isfinancially very painful indeed, andrelegation is a very real possibility.

• Hope for the best, plan for the worst.

A successful FAT is the best possiblepreparation for a successful SAT but not aguarantee of a repeat result. If theequipment is stand-alone then the SAT willoften be a repeat of the FAT in the finallocation with a few differences e.g. mainspower in place of generators, differentambient temperature etc. If the equipmentis to be incorporated into a larger systemand this normally means interfacing withother equipment then the SAT is a muchmore complex undertaking.

Interested? Then look out for The Sequel –SAT where we examine the fine detail,potential pitfalls and rewards of SiteAcceptance Testing.

Written by Jim Casey, Chief Technical Officerand Lead of Malin Skunks, Malin Group

BOOK RECOMMENDATIONS...

WINNERS: AND HOW THEY SUCCEED BY ALASTAIR CAMPBELL

THE INFINITE GAME BY SIMON SINEK

A motivational piece, by the well-knowncommunications guru, Winners: And HowThey Succeed is an illuminating and insightfulinvestigation into the traits and qualitiesshared by winners across various spheres:politics, sport, entertainment. As you wouldexpect from Campbell and hiscommunications background, the book isclearly constructed with simple yet effectivemessaging, with the main posited pointbeing the importance of objectives, strategyand tactics. Some of his examples are a littleforced, some lack critical reflection, yetothers are illustrative, enlightening andenjoyable.

He clearly demonstrates that hard work,practice, making mistakes, owning thosemistakes and learning from them andultimately never giving up, all are commontraits found in winners. Definitely one togently inspire!

This book looks at two fundamentallydifferent approaches to work and life bycomparing and contrasting a closed, finiteview on goals and purpose versus an open,infinite one. Now while this sounds very highbrow, it can be boiled down to the simpleethos of deciding to play to simply win orplay for the love of playing itself and definingcommercial success as enough to allow youto continue playing. The former may driveshort term successes, or even some longterm ones, but the latter is much more likelyto create an enterprise that will survive themost trying of times.

There is a particularly interesting section inthe book that looks at the responsibility ofbusinesses and argues very strongly against

the notion of Friedman that the purpose ofbusinesses is to serve its shareholders bydelivering profits back to them. He contraststhis with the view of Adam Smith whoargued that businesses are there to serveconsumption and the consumer while beingaware of the desire of self interest for this tobe defined in terms of production rather thanthe end goal of serving a need.

The book also has lots of advice oneverything from your mission (defined asyour Just Cause), to leadership styles andteam work.

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AN INSIGHT INTO ANCHORSELECTION

Anchors have a long history, dating back asfar as the existence of vessels themselves.Despite this, the subject of anchor selectionis often overlooked. This article will explorethis topic in more detail, investigating thediffering anchor types, their benefits,disadvantages, and common types ofusage.

Anchors ensure that a vessel remainssteadfast when tethered, whether this is tothe seafloor or to a permanent fixture suchas a quayside. Although early anchors wereoften primitive and simple, anchor designhas evolved to provide various novel and afull range of innovative, versatile solutions.As engineering advances, so too mustanchor design and development – whetherit be to anchor a 400m long cargo vessel, asemi-submersible drill rig or a series ofoffshore wind turbines. Each of theseapplications require a specific anchor,however, not all anchors can be used for allapplications.

There are various considerations whenselecting an anchor, however the primarydriving factors are:

• Inshore or offshore mooring• Water depth• Size and mass of moored vessel

Inshore Mooring

Inshore moorings require the least complexanchors and usually quayside bollards areused. These bollards allow a vessel to moor“alongside” a quay or berth, by connectingthe vessel’s own mooring wires/ropes tothe bollards and then tensioning the lines toprovide holding capacity. In most cases, asthe weather exposure tends to be less asquaysides are designed to providesheltered mooring, bollards prove suitableto hold a vessel in place. However, in the

case that the mooring bollards do notprovide enough capacity, mobile mooringwinches can be installed along the quaysideand are used in the same manner. This isillustrated in figure 9.

Mooring winches are offered in varioussizes, with a range of holding capacities andbrake loads - a very widely used solutionwhen mooring large vessels alongside aquay or berth.

Offshore Mooring

Unlike inshore moorings, offshore applicationshave more anchoring methods, as shown infigure 10, where the anchor selected is basedon the water depth:.

Deadweight Anchors

Of the above, deadweight anchors are thesimplest solution, and are still regularly andwidely used. The working principle of adeadweight anchor is in the name; they rely onsheer weight to provide anchoring capacity,usually being a concrete or metal block, whichis dropped to the seafloor, enabling vessels tothen hook up. An example is provided in figure11.

The main benefits of this anchor are twofold:versatility and cost effectiveness. As the massof the anchor provides the holding capacity,they may be deployed on any seafloorcondition, where other anchor types require acertain seabed profile or seabed material.Secondly, the cost of such an anchor may be farless than other alternatives, as they require nocomplex engineering, manufacture, or testing.In short, they are easy to design and fabricate.

However, deadweight anchors do have somelimitations, particularly their holding capacityefficiency. Some modern-day anchors mayprovide holding capacity nearing 50 times thatof the actual anchored mass, whereas a deadweight anchor’s capacity is relatively close tothe mass of the anchor itself (in direct tensionand negating buoyancy). As such, theseanchors tend to be reserved for lightapplications, in relatively calm conditions, for

example, near shore mooring of small crafts orvessels.

Drag Embedment Anchors

Drag embedment anchors are some of themost versatile and best performing anchorsavailable today. They rely on being “dragged”along the seabed by an anchor handling vessel,which coupled with their design, forces theanchor to submerge itself in the seabed. Thedeeper the anchor is laid; the more holdingcapacity is provided.

There are various shapes and designs availablefor a drag embedment anchor, however recentdevelopments have resulted in a two-piecesystem, comprising of a “fluke” and a “shank”where the fluke can be set to different anglesto suit different seabed characteristics. Thesehigh holding capacity anchors can provide up to~50 times their own weight in holding capacity(in the right conditions) and are consideredvery easy to handle and install.

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fig. 10 / Various offshore anchoring methods

fig. 11 / Deadweight anchor just before it isdropped to the seafloor

fig. 9 / Quayside bollard and mobilemooring winch

An example is shown in figure 12.

Drag embedment anchors are widely used inthe offshore industry, primarily for drill rigs,production platforms and FPSO’s due to theirhigh holding capacity. They are limited todeployable water depth however, as thedeeper the water becomes, the longer thecatenary is, and as such the weight of theanchor line itself increases. They require arelatively shallow catenary to ensure little to nouplift is subject on the anchor, as this can resultin dislodging. As well as a shallow catenary,engineers will routinely design a dragembedment mooring line to allow for a lengthof grounded line in front of the anchor, to assistin reducing uplift. This adds to the line lengthand as the line length increases so too does thefootprint of the anchor spread and the weightof the mooring line, which must be taken up bythe vessel fairleads which may become overutilised.

Pile Anchors

As illustrated in figure 10, there are varioustypes of pile anchor, namely: driven pile,gravity pile and suction pile. All these types usethe same working principle and share commoncharacteristics; they are all also capable ofwithstanding horizontal and vertical loads andare designed to resist vertical loading primarily.The benefits of pile anchors are that themooring spread footprint may be reduced insize, in comparison to a drag embedmentspread, as the normal angle between theseabed and the mooring line can be increased.

In some spreads, such as those which utilisetaut leg mooring, 90-degree mooring lines canbe laid - it is these characteristics which makepile anchors popular in ultra-deep-waterapplications.

The theory behind pile anchors is that the massis submerged into the seabed and the depth ofsubmersion provides the holding capacity,coupled with some clever engineering in thecase of the suction pile. The installation ofgravity piles relies on the mass of the anchorbeing dropped from the back of a vessel andthe kinetic energy gained as the anchor fallsthrough the water column will provide enoughimpact force to drive the anchor into theseabed.

In comparison, driven pile anchors are loweredto the seafloor via a crane, as illustrated infigure 13, and the initial impact will result insome embedment of the anchor. However, theinstallation workpiece includes a large“hammer” which will then drive the pile furtherinto the seabed until the desired embedmentdepth is achieved.

Finally, suction piles are the most complex ofthe available pile anchors and have aninteresting working principle which relies oncreating a vacuum within the anchor to providethe holding power. The suction pile anchorrelies on its hollow shape to ensure holdingcapacity – the pile can be described as ahollow, capped cylinder where the undersideremains open. The restraint is provided bydropping the large “can,” as shown in figure 14,to the seafloor where >~60% of the mass willsubmerge under its own weight (in optimalcases). A remote operated vehicle (ROV) isthen used to activate a valve on the topside ofthe can to discharge the trapped waterbetween the seabed and the capped end of thecan, which creates a vacuum.

As this brief insight into anchoring illustrates,modern engineering has made it possible tomoor in ever increasingly difficult locations,water depths and environments with a solutionfor any application.

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fig. 13 / Drive pile anchor lifted by crane

fig. 14 / Suction pile anchor

Written by Calum Reid, Graduate NavalArchitect, Malin Abram

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fig. 12 / Two piece drag embedment anchor

HEAVY LIFT TIPCHOOSING THE CORRECT

ANCHORSo you have been tasked with designing amooring system for an offshore installation? Doyou know which anchor is going to be bestsuited for the job? And what about anyconsiderations you must take into account toreach the right decision?

Not all anchors are suited to all applications:although some are more versatile than others,there are some which simply will not work incertain environments. To help ensure that youmake the best selection, there are some keyfactors you must consider when selecting ananchor:

� What is your mooring depth?� Do you know your seabed condition?� How large is the moored vessel?� Is this an offshore or inshore

mooring?� Are you mooring alongside a quay?

These are all very important questions to posewhen selecting the correct anchor. Only whenyou know all this information as a base point,can you then make an educated decision onwhat mooring system is to be used.

Assuming that you are not mooring alongside,in which case your options become lessened,

probably the most versatile and widely usedanchors is the “Drag Embedment Anchor”.

These anchors come in a range of sizes, fromsmall 1 tonne units, to bespoke 50+ tonneanchors which can also be ballasted withconcrete to provide additional holding power.Drag anchors can also be optimised bychanging the angle of the “fluke”, where thefluke is the bit that does the digging, like ashovel. This ensures that the anchor embedsitself correctly in the seabed and reaches thedesired depth – which is paramount in ensuringthe anchor does not slip during operations.Alternatively, if the fluke is not set to thecorrect angle, you risk the anchor notembedding at all and simply skidding acrossthe seabed – incurring cost and time delays inresetting.

There are a lot of anchoring options availableon the market, however, following a structuredlist of considerations such as this will ensurethat you make the right choice.

Written by Calum Reid, Graduate NavalArchitect, Malin Abram

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CHOOSING THE CORRECTANCHOR

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DESIGN AND FABRICATIONOF LIFT BEAMS

THE HEAVYLIFT ENGINEER

The design and fabrication of lift beams is aninvolved process requiring both practicalknowledge of their function and use as well astechnical understanding involved in thestructural/mechanical design. Within the body ofregulations Lifting Beams are defined as ‘liftingaccessories’ such that they are not attached tolifting machinery, allow a load to be held, areplaced between the machinery and load and areindependently placed on the market. The keypieces of legislation relating to lifting beam are asfollows:

Design

• Supply of Machinery (Safety) Regulations2008

Operation

• Lifting Operations and Lifting EquipmentRegulations 1998 (LOLER)

• Provision of Use of Work EquipmentRegulations (PUWER)

It should be noted that Supply of Machinery(Safety) Regulations do not apply to seagoingvessels, mobile offshore units and machineryinstalled on such vessels. In this case a suitablecertification authority is required such as LloydsRegister, DNV, ABS, BV, etc.

This article will discuss the design process for liftbeams which is broadly similar for lift beams usedin onshore and offshore applications. Note thatwhere the term ‘lift beam’ is used, it can also beextended to include spreader beams and othertypes of similar lifting accessories. It is alsoassumed that these take a similar form consistingof lift point(s) and structural members.

Design

When an object is lifted there is a change insupport conditions and as such a change to theload path from the object to the ground now vialifting equipment, accessories and rigging. Liftingand spreaders beams are used as a means ofcontrolling and directing the load path and as suchallow objects to be lifted in a safe and controlledmanner.

It is suggested that lifting requirements should beconsidered throughout the design of any heavy,

large, or otherwise cumbersome object orstructure.

There are several key considerations required forthe design of a lift beam.

• Weight of item to be lifted• Centre of Gravity (CoG) of item to be

lifted• Practicalities

• Space envelopes• Hook height available or required• Fabrication

Weight

The overall mass of the object can be determinedin a range of ways, varying in accuracy, such asmaterial take-offs, 3d model or physicallyweighing the structure – it may also be providedby a client. Note: Weight control informationshould stem from a well-defined anddocumented system. Depending on the reportingof the weight and maturity of the design it is goodpractice to include a weight contingency factors.Guideline figures for increasing the weight areprovided in the table below.

Once the weight is known, the lift beam can bedesignated a Safe Working Load (SWL) or WorkingLoad Limit (WLL). The SWL/WLL should alsoaccount for rigging required. The SWL/WLL is avalue, or set of values, based on the operationalrequirements of the lifting beam and is themaximum load that the lifting beam can safelylift, provided it is rigged in the correct manner. Itis possible for a lifting beam to be certified to arange of SWLs and corresponding geometriclimits. In any case, the SWL/WLL is to be clearlymarked on the lift beam.

Centre of Gravity (CoG)

The second key consideration is the Centre ofGravity (CoG) of the item to be lifted. The CoG canalso be determined in a number of ways frommanual calculations to output from a 3d model –or again it may be provided by a client. Similar tothe weight accuracy factor it is also prudent toaccount for centre of gravity accuracy. There aretwo primary methods for accounting for CoGinaccuracy

Table 1 Guideline weight contingencies

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There are two primary methods for accounting forCoG inaccuracy in the design with the chosenimplementation depending on the type of lift andsensitivity of shifting the CoG:

• Considering a CoG envelope – used foroperation where resulting load effects, oroperations, are more sensitive to change ofCoG position. This is depicted in the followingimages, or;

• Applying CoG contingency loads factors – usedwhere there is a more linear relationshipbetween CoG shift and resulting load effects.

The first of these considers CoG in extremepositions of a defined envelope and the secondincreases the entire weight and as such increasesthe full load but does not change basic loaddistribution. The size of a lift envelop will bedetermined by the appropriate design standard –typically these could bed in the region of 0.05L x0.05B x 0.05H for an early stage design. In thedesign the most onerous CoG position should beadopted.

The location of the CoG will determine the positionof the lift hook point, and from this, the riggingarrangement, and overall lengths. The lift point is tobe located in-line with the centre of gravity.Rigging lines typically have a minimum angle of45° with a preference for 60° (to the horizontal).

Practicalities

Alongside the weight and CoG consideration of thepractical elements such as, but not limited to,space/geometry envelopes, crane hook height,fabrication limitations and operational conditions.These factors will influence the type of lifting beamthat is designed. To fully understand the practicalconsiderations desktop and/or site survey will berequired, in order to fully understand such things as

the limits of the lifted item, site, fabrication facilityand craneage available.

Lift beam design

Once the above information has been obtained theinitial arrangement and sizing can be determined –oftentimes from simplistic, manual calculations.The SWL/WLL is determined from the Static HookLoad (SHL) which consists of gross weightcombined with rigging weight. A conservativeestimate is often required for the rigging weightwhich is then revised once the rigging is finalised.It should be noted that it is generally good practiceto round up with static hook load to provide a roundSWL/WLL number.

The dynamics of the lift are accounted for byapplying a Dynamic Amplification Factor (DAF). TheDAF is determined through consideration of aspectsof the lift beam use such as the location (offshore/inshore/onshore), the gross weight and liftingspeed.

From this a basic dynamic load is determined.Further to this a proof load is to be determinedbased on the safe working load of the system. TheProof Load Factor (PLF) is determined from asuitable lifting code such as Lloyds Register ofShipping Lift Appliances in the Marine Environment(LAME).

Gross weight = calculated/measure weight xweight contingency factor (x CoG accuracy)

Duty Factor = A factor depending on the frequencyand severity of the load lifted

Static Hook Load (SHL) = Gross weight + Riggingweight (x Duty factor)

Dynamic Hook Load (DHL) = SHL x DAF

Proof Load Factor (PLF) = Additional load factorused for testing the lift beam - typical values aregiven below taken from the International LabourOrganisation Register of Lifting Appliances andItems of Loose Gear [1]

Proof load = SWL x PLF

Proof load factors

These are applicable to lifting beams, spreaders,lifting frames and similar devices as provided by ILO[1]

Additional load factors (not all are alwaysapplicable) are applied to determine final dynamicload which are dependent on the use of the liftbeam. Factors include:

• Skew Load Factor (SKL)• 2-hook Lift Factor• 2-Part Sling Factor• CoG Shift Factor• Tilt Angle

With the loads calculated calculations can beundertaken to determine the loads in the riggingand lift points. Rigging items are rated items and assuch can be specified based on the SWL. It shouldbe noted that where rigging is used in a marineenvironment (dynamic) consideration should begiven to ensure the SWL of the item has sufficientcapacity for application.

fig. 15 / Plan of lift object with CoG in centre ofenvelope

fig. 17 / Spreader beams as used in a complexrigging arrangement

fig. 16 / Plan of lift object with CoG at extremeposition centre of envelope

Table 2 Proof load factors from ILO [1]

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Lift points

The geometry of lift point (also referred to as padeyes) is initially dictated by the size of shackle, andassociated pin, required. The width of the pad eyeis typically required to be at least 75% the widthof the shackle jaw and similarly the hole istypically sized such the pin is 94% the size of thehole.

The pad eyes are to be assessed individuallyconsidering the resultant sling force – accountingfor in and out of plane actions. The pad eyes are,normally, aligned with the rigging such as tominimise any out of plane loading. It is howeverboth good practice, and a requirement of somecodes, to include a nominal out of plane loading,typically 3-5%. The assessment can either be doneby manual calculations or finite element analysis.Manual calculations are the preferred methodgiven that pad eyes are, normally, simplestructures. The following critical checks arerequired in order to fully verify the pad eyestructure to a relevant national or internationaldesign standard.

The following should be assessed as a minimum:

Considering the Resultant Sling Force (RSF) thefollowing should be considered:

• Bearing stress• Tear out stress• Check plate welds

The tensile and shear components of the RSFchecking at both the hole, base and any othercritical locations:

• Direct tension• Direct in-plane shear• Direct out of plane shear• In-plane bending• Out of plane bending• Combined stress

Padeye connection to beam

The connection of the pad eye to the lift beam isto be assessed as well as the structure local to thepadeye. The preference for welding is fullpenetration welds over fillet welds however it isnot always possibly to achieve this. Commonweld arrangements for penetration welds includedirect butt and slotted arrangements. Slotteddetails are often preferred from a structural pointof view as they can eliminate issues such aslaminar failings or local stress concentrations – thismay not be the case for fabrication. However, themain pad eye plate is often required to be taperedto match the mating structure. Alternativearrangements could include lap welded details,using fillet welds, this may result in additionaleccentricities to consider.

fig. 18 / Force acting on a lift point

The engineer should strive to avoid local stressconcentrations through good detailing practices. Ifthese are unavoidable for practical reasons, theengineer should ensure they fully understand theload path and verify all aspects.

Lift beam design

The lift point and rigging arrangement willdetermine the how the forces are transferredthrough the structure. For example, a lift beam witha single hook point in the centre will be in bendingwhereas a spreader beam will largely be incompression. This can influence the type of sectionwith spreader beams often fabricated from CircularHollow Sections (CHS) or other closed sections.

The lift beam itself is to be designed in accordancewith a suitable national or international designstandard considering the most onerouscombination of loading acting on the beam. Typicaldesign codes for this would include Eurocode 3,AISC or Lloyds Register Code for Lifting Appliancesin the Marine Environment – with the engineertaking note of the design philosophy (ASD or LRFD).As for the pad eye it is often sufficient to verify thebeam by manual calculations, however frameworkor finite element analysis tools may be required ifthe beam is sufficiently complex. When using suchtools, it is imperative that the engineer has a goodunderstanding of the tool and its limitations,particularly understanding where additional localcalculations may be required to fully verify thestructure.

Fabrication, marking and testing

The fabrication of a lift beam should be undertakenin accordance to an agreed fabrication standard.Once a fabrication standard has been determinedagreement is required on such items as weldprocedures, qualifications of welders, non-destructive testing (NDT) procedures, NDTpersonnel qualifications and NDT acceptancecriteria. These items should all in line with therelevant standards.

Proof Load Testing

There are two main means of "justification” for alift beam – firstly by calculation and secondly byproof load testing.

Lifting points, lifting frames and spreader barsintended for non-routine operations do not requireto be proof loaded tested, provided full designcalculations are provided and verified bycompetent person(s) alongside a full programme ofinspection. However, where practical proof loadtests should be undertaken. The proof loadrequirements are determined dependent on theSWL and its application, as discussed in the sectionabove.

Where a load test is to be undertaken the test mustbe representative of the actual design loadingconditions with measures taken to ensure theaccuracy of the testing equipment. Applied loadsshould be within +/- 2% - of the proof loadrequirement and verified by use of calibrated loadcells or pre-weighing test weights. Acceptancecriteria should be agreed prior to the test andverified after the test.

fig. 19 / Slotted connection fig. 20 / Butt welded connection

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Inspection

Fabrication materials shall comply with therelevant standards ensuring full traceability.

The lift beam will typically be inspected byassessment of the primary structural arrangementand workmanship, ensuring they are as detailed inthe approved plans. Where work is not as detailedin the plans it shall be rectified.

Non-Destructive Examination is to be carried outby sufficiently qualified personnel. Note that thisshould be undertaken prior to painting. Typicalrequirements for welded construction are given asfollows, where a critical weld is one where failurewill result in loss of the load, primary welds arethose in the main load path and secondary weldsdo not form part of the main load path (platforms,service fittings, etc).

Butt welds

• Critical welds - 100% Visual, 100% MagneticParticle Insepction (MPI) & 100% UltrasonicInspection

• Primary welds- 100% Visual, 100% MagneticParticle Inspection (MPI) & 20% UltrasonicInspection

• Secondary welds - 100% Visual

Fillet welds

• Critical welds - 100% Visual, 100% MagneticParticle Insepction (MPI)

• Primary welds - 100% Visual, 100% MagneticParticle Inspection (MPI)

• Secondary welds - 100% Visual

In addition to welds, it is also often required toinspect the material local to the lift point forlaminar discontinuities.

Painting and Marking

Once the testing and inspection has beencompleted the lift beam can be painted andmarked up with required information – specificallythe SWL/WLL. For lift beams subject to the Supplyof Machinery (Safety) Regulations the followingmarkings are required:

• Marked for UKCA (or EC, if applicable)• Name and address of the manufacturer• Serial number• Year of construction• Total mass of assembly• SWL/WLL – including all configurations

(where appropriate)

Markings should confirm with published standardssuch as BS EN ISO 7010 or other appropriatelegislation.

References

1. International Labour Organisation, Register ofLifting Appliances, and Items of Loose Gear, 1985

fig. 22 / Lift being under test load

Written by Alasdair MacDonald, Team Leader &Senior Structural Engineer, Malin Abramfig. 21 / Lift beam and spread beams in used

fig. 23 / Forces acting on a spreader beam (L)and lift beam (R)

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CONFIGURATIONS TIPS INSOLIDWORKS

SOLIDWORKS configurations are used tocreate multiple versions of a part orassembly within a single file number. Thedifferences between the configurations canconsist of changes in dimensions, thesuppression of different features or themodification of parameters.

Configurations are mostly used to createsimplified versions of a single part, for usein assemblies. An example of this could bea hex head screw.

When creating your initial screw size,M30x100mm long, you would create a partnumber and add your description within thise.g., M412-DRG-001 M30 Hex Head Screw.Notice you would not state a particularlength within the description as the mainpurpose of this is to build up configurationsof different lengths for the same diameterscrew within this single part number.

Once your component is created and yourthreaded dimension length is at 100mmlong, you then go into the configurationmanager tab, and name your firstconfiguration, M30 x 100mm long.

After this, you right click the top item andadd configuration, naming this with yournew length, M30 x 150mm long:.

Within your new configuration, you thensuppress the original 100mm long featurecreated in your initial configuration andcreate a new threaded dimension length at150mm long.

You will now have two different lengths ofscrew within your single component; thismeans that you can easily select either onewithin your assembly. This process may berepeated with as many different lengths ofM30 screw as required.

Written by Barry Leitch, Draughtsman, MalinAbram

Named configuration

HEAVY LIFT TIPCONFIGURATIONS TIPS

IN SOLIDWORKS

New feature within configuration

Suppressed feature

New configuration

Configuration manager tab

33

fig. 24 / Solidworks configurations

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