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UK P&I CLUB

Tanker mattersA focus on some of the issues surroundingtanker fleets in the P&I world

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Bulk oil cargoes –shortage andcontamination claimsOver recent years there has been a marked increase inthe incidence of claims arising from the carriage of oilcargoes. The claims are often substantial and mayallege either shortage or contamination or both. In thepast it was believed that measurement inaccuracies andall the problems related to the carriage of oil in bulk wereunderstood. Recent research and advances intechnology and analytical techniques have uncoveredinformation which is of considerable significance. Thepurpose of this article is to provide guidance on howtanker operators can minimise the risk of cargo loss ordamage and defend themselves should claims arise.

Oil shortagesIn general, oil shortage claims are based upon adiscrepancy between the quantity of cargo as stated inthe bill of lading and the outturn quantity as calculated inthe discharge port. Both these figures are frequentlyderived from shore-tank calibration data. The mostcommon arguments are that:

● The ship is bound by the figure stated in the bill oflading

● The shore tank calibrations are more accurate thanthe ship’s tank calibrations

● The oil has become contaminated by water afterloading

● Some oil remains onboard the ship.

The carrier’s defence is commonly based upon theaccuracy of the ship’s cargo figures and seeks todemonstrate that they were comparable with the bill oflading figure, that there was no significant in transit loss,that any onboard quantity (OBQ) prior to loading hasbeen taken into consideration and that all the cargo hasbeen discharged with none remaining onboard (ROB).

In the following pages each phase of a typical tankervoyage is followed chronologically and likely causes ofdifficulty are considered.

Before arrival at the load portThe correct preparation of the cargo tanks in readinessfor the grade of cargo to be carried is covered in thesection dealing with contamination claims. Aside fromensuring the minimum safe quantity of clean ballast forarrival, the cargo officer should prepare a loading plan

taking into account stability, trim and stress. Wheredraft restrictions permit, it may be advisable to plan forleaving the loading port with a trim that avoids the needfor internal transfers of cargo during the loadedpassage. The inert gas system, if fitted, should befully operational in readiness for the forthcoming cargooperation. The oxygen content of the cargo tanksshould be as low as possible before arrival and a recordof all tank readings should be maintained.

On arrival at the berthOnce the ship is securely moored it is important toarrange liaison with representatives from the shoreloading facility and to ensure continued goodcommunications throughout the loading. All relevantinformation must be exchanged between ship and shoreincluding details of the ship’s loading plan, maximumloading rates, shutdown procedures,safety regulations and cargo data.

Before loadingAfter all ballast has been discharged other than anypermanent ballast which may be dischargedsimultaneously with the loading of the cargo, the ship’scargo valves and pipelines should be correctly set forthe reception of cargo and the relevant tank valvesopened. Any residual ballast water should be pumpedor drained from the pipeline system either overboard inthe case of clean ballast or into a suitable slop tank butalways in compliance with the local oil pollutionregulations. Before loading, it is customary for a jointinspection of the cargo tanks to be made by shorerepresentatives and ship’s officers to confirm that thetanks are properly drained of water and in a suitablecondition to load the designated cargo. In general, thecompletion of such an inspection does not relieve theowner of his responsibility to ensure the correctcondition of the cargo tanks. In large tankers and wheretanks are inerted, such inspections are difficult and itmay be necessary to rely on the ship’s gaugingequipment rather than any visual inspection.Preparations for the loading of multigrade cargoes aredealt with under the section covering cargocontamination claims. The measurement of any OBQshould be carefully undertaken preferably jointly withthe shore representatives. The depth of any residuesshould be measured at as many locations as possibleand at least at the forward and after ends of the tanks.Tank cleaning hatches should be utilized as appropriate.

During loadingThe loading sequence of tanks should be planned inadvance with the ship’s stability and stress conditions inmind. It is customary to begin loading at a slow rate but

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once it is established that cargo is entering the correcttanks and that there are no leaks from hose connectionsor any other difficulties, the rate is increased to themaximum. It is recommended that at an early stage thecargo officer should satisfy himself that the correctgrade of cargo is being loaded, either by checking thespecific gravity of a sample or at least by visual means.In modern tankers the ship’s instrumentation mayfacilitate remote monitoring of temperatures duringloading but in any event it is essential to measureaccurately and to record the temperature in each tankduring loading. It is wise not to use an average of thetank temperatures since this leads to inaccurate cargofigures.

The loading rate should be monitored and it isrecommended that ullages and the corresponding tankvolumes be recorded in the deck log at least at hourlyintervals. Any changes in the loading rate or anystoppages must also be recorded. During the finalstages of loading the rate should be reduced to aminimum in order to permit measurement of the quantityof cargo so far loaded and to calculate the correctfinishing ullage in the last cargo tank.

On completion of loadingBefore the cargo hoses are disconnected, the ship’sfigures must be calculated in order to check that thecorrect quantity of cargo has been loaded. Whilst it is inthe ship’s interests to measure the cargo onboard ship,it is customary for various witnesses to attend thisoperation and in some cases to make independentcalculations. These witnesses may includerepresentatives from the loading terminal, the shippersand the charterers. It is of prime importance that the

measurements of ullage, temperature and whereappropriate, water dips are agreed by all concerned,although it must be accepted that the methods ofcalculation employed thereafter may not always beconsistent. It is generally accepted that the latestedition of the API/IP Petroleum Measurement Tablesare more accurate than the old tables, but it should beborne in mind that all tables are based on the averagecharacteristics of a range of oils. Where a surveyor isattending on the ship’s behalf he should collaboratewith the ship’s officers in order to ensure that noinconsistencies arise in the calculations.

Ship’s tanks may be calibrated using imperial or metricunits of volume and the quantity of cargo may beexpressed in various units including long tons, tonnesor barrels. Whichever units are applied, it is essential tocompare like with like. The use of standard volume maybe considered preferable as it is less susceptible tomisinterpretation by observers or laboratories. Theappendix to this article shows the various terms used inthe measurement of liquid cargoes and theabbreviations in common use.

At this point it may be worth considering in some detailthe degree of accuracy which may be expected whenullaging tanks, measuring temperatures, takingsamples or quantifying free water.

Ullaging

This is the measurement of the distance from the datumpoint at the top of a tank to the surface of the liquidcargo. This is usually done by means of a steel tapefitted with a weighted brass bob. Many tankers havefixed gauging equipment in each tank and electronic

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measuring devices are also available. Ullaging is bestcarried out when the ship is on an even keel and with nolist: otherwise inaccuracies may creep in despite theapplication of trim corrections. A ship whether afloat,alongside a jetty, at anchor or at sea, is a movingplatform. Whilst it is not implied that ships necessarilyroll heavily when berthed, nonetheless slight movementwill affect the accuracy of measurement. In any singletank, a difference of one inch in the ullage may involve avolume of several hundred barrels.

Some factors may affect the calculation of onboardquantities particularly residues on tank floors andstructures, which will vary with the age of the vessel andprevious cargoes carried. It is not unusual for ullages tobe recorded for the purpose of determining ROB andOBQ when the trim of the vessel, at the time of survey,is such that the ullaging tape or sounding rod is notperpendicular to the ship’s tank bottom on contact. Insuch cases it follows that the depth of ullage obtainedmust also be inaccurate. Clingage is a further area forconsideration because whilst crude oil washing (COW)reduces clingage with most crude, there are a fewtypes of crude where the reverse is true.

Water dips

Free water beneath a crude oil cargo is normallymeasured with a sounding rod. Using water-sensitivepaste, the presence of water can be detected by achange in the colour of the paste. Interface tapes mayalso be used for the detection of free water.Unfortunately, neither of these can be used todistinguish accurately between an emulsion and freewater. Each method involves the risk of inaccuracieswhich can only be determined by proper sampling andanalysis techniques.

Temperature

The temperature of liquid in a vessel’s tank is generallyobtained by the use of a cup case thermometer,although some vessels are now equipped withelectronic temperature sensing devices. Cup casedthermometers are unreliable and errors of ±2 to 3°C arenot unknown. When taking temperatures, great careshould be exercised to ensure that the thermometer isnot affected by the environmental temperature after ithas been removed from the oil.

The vertical positioning of the thermometer in a vessel’stank particularly at the discharge port is critical becausesignificant temperature variations can develop withinthe cargo tanks during the voyage. Furthermore, astemperatures vary from tank to tank, calculations ofquantity must be calculated using individualtemperature corrections for each tank. The use of an

arithmetical average for the whole ship is, as previouslymentioned, inaccurate and contributes to ‘paperlosses’. An error of1°C in temperature produces aninaccuracy in the volume at standard temperature ofapproximately 0.1%.

Sampling

The ship when calculating cargo quantities, has to relyupon certain data supplied from the shore, in particularthe density of the cargo which is calculated after theanalysis of samples. Shoreline samples may howevercontain inaccuracies and cannot always be acceptedas being representative of the cargo loaded. It isrecommended that with crude oils, the standardsampling ‘thieves’ should not be used but that cleansample bottles be used for individual samples fromeach level, (i.e. top, middle and bottom of each of theship’s tanks) and clearly labeled. Regrettably, samplingis often undertaken using a one litre ‘thief’, each samplebeing decanted into a larger sample can.

During such an operation volatile fractions may be lostto the atmosphere and the density established from thefinal mix does not represent the true density of thecargo in each tank. This, in turn, may later have asignificant effect upon the calculation of weight andbottom sediment and water. The importance ofsampling as a measure to counter contamination claimsis dealt with later in the article.

Measurement errors

Studies by a major oil company revealed that ameasurement error of ±0.21% may occur whencalculating the measurement of volumes and an error of±0.25% when calculating weights. Thus, measurementerrors may easily account for what has previously beentermed a ‘measurement error loss’ or ‘measurementtolerance’.

Completion of documentation

Once the calculation of the ship’s figures has beencompleted, the shore installation will provide a shorefigure. It is generally this figure which is used on the billof lading. For the reasons given in the section dealingwith cargo measurement, it is most unlikely that the twofigures will precisely coincide. In practice, and in thevast majority of cases, the discrepancy is small and ofno great significance and the master of the ship willhave no difficulty in reconciling the figures nor in signingthe bills of lading. In each case, the gross figuresshould be compared and the ship’s experience factorshould also be taken into consideration.

On those occasions when there is an exceptionaldifference between the bill of lading figure and the

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ship’s figure, the master should decline to sign the billsof lading. He should insist on a thorough check of allmeasurements and calculations, including thoseashore, in order to ascertain the cause of thediscrepancy. When checking the shore figuresdifficulties may arise because the measurementstaken in the shore tanks before loading cannot beverified once the cargo has been transferred. Thechecking of the shore figures may, therefore, dependupon the accuracy of the records kept in the shoreterminal. In the majority of cases this investigation islikely to be successful and the figures will be correctedand easily reconciled. The reasons for grossinaccuracies may include:

● Ullages wrongly measured

● Tanks filled but not taken into account

● The contents of pipelines not allowed for

● Wrong temperatures or densities

● Cargo mistakenly loaded on top of ballast

● Cargo lost in the shore installation

● Incorrect meter proving.

On occasions, despite such exhaustive checks it maybe that the two calculations cannot be reconciled andthe master then finds himself in a dilemma. On the onehand, he will doubtless be mindful of the Hague Ruleswhich provide:

“No Carrier, Master or Agent of the Carrier shall bebound to state or show in the bill of lading any marks,number, quantity or weight which he has reasonableground for suspecting not accurately to represent thegoods actually received for which he has had noreasonable means of checking.”

On the other hand, he will be conscious of thecommercial pressures which dictate that the berth mustbe vacated and that the voyage must not be delayed.There is no inflexible rule to be followed which will applyin every case.

The master should note protest. He should certainlynotify the ship’s agents and instruct them to urgentlyinform the owners of the problem as well as thecharterers, the shippers and any consignee, or notifyparty named on the bill of lading. The master shouldgive full details of the available figures and ask theparties notified to inform any potential purchaser of thebill of lading of the discrepancy. It may be difficult for themaster to contact all the parties named but the ownershould do this at the earliest possible opportunity.Ideally, the master should be able to clause the bills of

lading but in practice this creates many difficulties. Heshould, therefore decline to sign the bills of lading orwithhold authority for anyone else to sign until thedispute has been resolved. In any event the master orowner should immediately contact the Association orthe Association’s correspondents.

Early departure proceduresIn certain busy oil ports, it is the practice, in the interestsof expediting the turnaround of tankers, to offer themaster the opportunity to utilise the ‘early departureprocedure’. This system was devised in the light ofmany years experience of tanker operations and shorefigures after loading. On arrival at the loading berth themaster agrees that on completion of loading, theloading hoses will be immediately disconnected and theship will sail. As soon as the bill of lading figures areprepared, they are cabled to the master who then,provided he is satisfied, authorises the agent to sign thebills of lading and other related documents on hisbehalf. On no account should the master sign the billshimself before sailing without the correct figures beinginserted.

Shipboard recordsIt is essential for the defence of possible cargo claimsthat the ship maintains certain documentary records ofcargo operations. Time charterers, particularly the oilmajors, are likely to place onboard their owndocumentation which they will require to be returnedpromptly at the end of each voyage. Typical returnswould include:

● A voyage abstract (deck and engine)

● Notice of readiness

● A port log

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● Pumping/loading records

● Stowage plan

● Loading and discharge port calculations

● Details of any cargo transfers.

They may also include records of all oil transfer, whetherloading, discharging or internal and including bunkeringoperations. It should be noted that such records willassist not only with the defence of shortage andcontamination claims but with handling of otherpossible disputes including performance claims anddemurrage and dispatch disputes. The need to keep fullrecords of bunker quantities and to properly maintainthe oil record book cannot be over emphasised.

During the voyageProvided the ship’s fittings are properly maintained, thecargo will require little attention during the voyageunless heating is required. In such cases, it is importantto follow the charterer’s instructions particularly bearingin mind the specifications of the cargo carried. In somecases failure to heat the cargo properly may lead tosevere difficulties. When crudes requiring heating arecarried, particularly those with high wax content, it isimportant that the charterers provide clear instructionsfor heating both on the voyage and throughoutdischarge. Often, heating instructions are notsufficiently precise with the charterers relying on theexperience of the master. Usually, it is wise to heat early

in the voyage in order to maintain the temperature ratherthan to be obliged to raise the temperature of the cargosignificantly at the end of the voyage. If there is doubtabout the heating instructions, the master should checkwith the charterers. The tank temperatures should berecorded twice daily.

Attention should be paid to the condition and operationof the pressure-vacuum valves on the tank ventingsystem in order to ensure that they are functioningcorrectly. Failure to operate these valves properly maylead to a significant loss of product during the voyage.

Finally, as mentioned earlier, the loading has beencarefully planned, there should be no necessity totransfer cargo between cargo tanks during the voyage.Indeed this should be avoided unless absolutelynecessary as differences between ullages andsoundings taken before and after the voyage invariablylead to disputes when defending shortage claims.Ideally, the two sets of readings should not differ to anydegree. Owners should discourage the practice andinsist that any transfers which the master considersurgent and essential be reported and properly recordedin the oil record book. Many charter parties do in factrequire the master to notify the charterers of anycargo transfers.

Before arrival at the discharge portA proper discharging plan should be prepared, takinginto account any restrictions or requirements. It mustinclude a careful check on not only the trim conditionduring discharge but on the stress conditions. Careshould be taken to ensure that the parameters laiddown by the shipbuilders are adhered to. It is alsoimportant to take into account the required dischargingtemperature and the need to maintain this temperaturethroughout the discharge. When discharging in portswhere low sea temperatures prevail, this may requireconsiderable vigilance. In those tankers fitted with inertgas and COW it is wise to ensure in advance that thesystems are fully operational in readiness for theforthcoming discharge.

On arrival at the discharge portOn completion of the arrival formalities, the need tocommunicate with representatives of the dischargingfacility is no less important than at the loading port. Fullliaison should include the exchange of all relevantinformation about the cargo, including the maximumdischarge rates, the discharge plan, safety procedures,shutdown procedures scheduled shore stops and anylocal regulations. If the ship is fitted with COW it mustbe clear whether COW is to be carried out, particularlybearing in mind any Marpol requirements.

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Before dischargeAs in the loading port, the measurement of the cargo isundertaken in the presence of the cargo receivers andpossibly other interested parties or their surveyors andincluding customs authorities. The remarks in thesection on cargo measurement apply equally in thisinstance. The utmost care should be taken in checkingand doublechecking the measurements. Themeasurement of temperature merits particular careespecially where heated cargoes are concerned. Againit is stressed that apparently small discrepancies intemperature can lead to significant differences in thefinal calculations and the temptation to ‘round off’temperatures or to use convenient averages should bediscouraged. It is essential to note the ship’s trim andlist at the time of ullaging – the ideal trim is with the shipon an even keel and with no list. When samplingcargo before discharge and particularly in the case ofheated cargoes, samples should be taken from the top,middle and bottom of the cargo tank.

On completion of cargo measurement, a comparisonshould immediately be made with the loading ullagestank by tank, in order to see whether there have beenany appreciable changes since leaving the loading port.Should any differences be noted, then the reasonsshould be immediately investigated and fully recorded.The ship’s responsibility should begin and end at thefixed manifold and the owners have no liability formeasurements taken once the cargo has entered thecomplex of piping which forms the average receivingterminal. Claims are frequently presented on the basis

of shore figures which are inaccurate and the mosteffective and economical way of repudiating liability maybe to recalculate these figures correctly. Itwould be beneficial for a surveyor representing theshipowner to check the shore reception facility, wherehe may be able to witness the taking of shoremeasurements. He may also be able to check thepipeline system, to verify its size and length and themethod by which its contents are ascertained beforeand after discharge as well as noting any valves whichlead off those pipelines which are in use. Some shorefacilities are reluctant to allow ship’s representatives tomake full checks in their terminals. It should be recordedif an inspection of the terminal or its operations isrefused.

Where shortage claims arise, they are usually based onthe shore figures and the owner must defend himself notonly on the basis of the accuracy of the ship’s figures,but also by challenging the accuracy of those shorefigures. It will greatly assist if the owners’ surveyor hasmade a thorough inspection of the terminal at the time ofthe discharge.

During dischargeOnce the necessary preparations have been completedaboard the ship and the shore installation has confirmedthat the discharge can commence, the cargo pumps arestarted in sequence. Where one or more grades ofcargo are carried, it may be possible to discharge eachgrade simultaneously subject to stress and trimconsiderations and any other restricting factors

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including the design of the ship’s pipeline system. Onceit has been established that the cargo is flowingcorrectly, the discharge rate should be increased to theagreed maximum. The rate may berestricted either by back pressure or by the capacity ofthe ship’s pumps. The rate of discharge should becarefully monitored throughout and recorded atintervals of no more than one hour. These recordsshould show not only the amount of cargo dischargedby volume but also the shore back pressure, thepressure at the ship’s manifold, the speed of the cargopumps and steam pressure or, in the case of electricalpumps, the amperage. If COW is being carried out, thisoperation must be closely monitored. Careful recordingof the discharge in the ship’s logs is essential if claimsare to be successfully defended.

The effective stripping of the tanks is important sinceclaims will undoubtedly be made against the owner forquantities of cargo remaining onboard. Provided theship has a good stern trim, the tanks have been wellcleaned and prepared prior to loading and providedalso that the ship’s pumps and pipelines are in soundcondition, it should be possible to ensure that anegligible quantity is left onboard. In the case of light orclean products there should be no problem althoughwhere heavier or heated cargoes are concerned, therewill inevitably be some clingage and perhaps somesediment remaining. COW will help to reduce thesequantities and care should be exercised when strippingheated cargoes to ensure that the tanks are drainedquickly, since once the level of the cargo falls below theheating coils, heat will be lost quickly and difficultiesmay be encountered.

Whatever type of oil is carried, it will be necessary to beable to demonstrate that ship’s valves, lines and pumpswere in good condition at the time of discharge,because this has an impact on the question of‘pumpability’. It might be assumed that oil is pumpableor unpumpable in the sense that it is liquid or not liquid.From the point of view of cargo claims however, it mustalso be considered whether, even if the cargo wasliquid, it could be pumped by the vessel’s equipment. Itis possible that small quantities of oil, particularly wherehigh gas cargoes are concerned, cannot be picked upby the pumps without the pumps gassing up. It could bethat due to sediments from the cargo or shorerestrictions on trim, the oil is liquid but cannot run to thesuction. The master should call in a local UK Clubsurveyor if he experiences difficulty in obtaining asuitable dry tank certificate. If pressure is applied to theship to sail before the surveyor can attend, the mastershould protest to the receivers and to the receivers’surveyor. If the surveyors are not prepared to certifycargo remaining onboard as unpumpable, they should

be invited to inspect the ship’s pumps. The receiversshould be informed that if they consider the cargo to bepumpable, the ship is prepared to continue to attemptto pump it until the UK Club surveyor arrives. Ownersshould ensure that the maintenance records for thecargo pumps are carefully preserved and that they areavailable when such disputes arise. Surveyors whocertify cargo as pumpable should be required to provethat they have tested the nature of the cargo and haveascertained that it can and does reach the suction in thecargo tank.

ROB claims may therefore arise in three different ways:

● By loss of heating or inadequate heating onboardships, sometimes coupled with low ambienttemperatures at the time of discharge.

● The physical properties of the oil and the ability ofthe pumps to pump it. The possibility of pumpsgassing up and loss of suction must be taken intoconsideration.

● Cargo sediments or trim restrictions which preventthe free flow of oil to the tank suction.

In the case of crude which does not require heating orwhich has a high vapour pressure, good crude oilwashing and a good stern trim will overcome mostproblems.

Frequently the charterparty will call for COW ‘inaccordance with Marpol’ and will allow additional timefor discharge when COW is performed. Naturally, if thereceiving installation will not allow satisfactory sterntrim or if they refuse COW either in whole or in part thenthe master should protest to the terminal and to thecharterers, stating that the vessel cannot be heldresponsible for any resulting cargo losses.

On completion of dischargeWhen the cargo has been completely discharged withall tanks and pipelines well drained, the cargo systemshould be shut down and all tank valves closed. A finaltank inspection is then carried out and inevitablyparticular attention will be paid by the shorerepresentatives to any cargo remaining onboard. Allvoid spaces, including ballast tanks and cofferdamsshould be checked to ensure that no leakage of cargohas occurred. This is particularly relevant on OBOvessels.

Dry tank certificateAfter discharge, a dry tank certificate will ideally beissued, signed by an appropriate shore representativedescribing any remaining cargo as ‘unpumpable’ and

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carrying an endorsement that the ship’s equipment wasin good working condition. In many places, shore cargoinspectors are reluctant to describe oil as ‘unpumpable’and may prefer to use the terms ‘liquid/non-liquid’. Thisis not satisfactory and should be avoided if at all possiblebecause it leaves cargo owners in a position to claimpumpability and to attempt to activate a charterpartyretention clause, albeit unlawfully, if the clause requiresthe cargo to be pumpable.

It is strongly recommended that masters contact theirUK Club representative and the ship’s operators foradvice if a dry tank certificate showing oil remainingonboard as being unpumpable cannot be obtained.

BallastingWhere permanent ballast tanks are fitted, it is normalpractice for these to be filled during the discharge inorder to expedite the ship’s departure. It is, however,recommended that other ballast tanks not be workedsimultaneously with cargo operations as this willcertainly entail the risk of contaminating the cargo.Should ballast, in addition to the permanentarrangements, be required then such ballasting is bestcompleted after the discharge and after the inspectionof the cargo tanks.

In-transit losses and their potentialcausesIn the past the standard defence put forward by ashipowner to a cargo shortage claim was that the losswas below or equal to 0.5% of the total cargo. Thisfigure, which originally stemmed from the cargoinsurance deductible, has been used by shipowners andcargo insurers as a yardstick for transit losses for manyyears. However, a number of courts, particularly in theUnited States, have rejected the concept of an automatic‘loss allowance’.

Nonetheless, there is every indication that the sameCourts would allow a ±0.5% ‘measurement tolerance’.In transit losses and their causes can be consideredunder four headings:

● The true in-transit losses during the voyage wherethe ship’s gross volume at standard temperature onloading is compared with the vessel’s gross volumeat standard temperature prior to discharge

● Theoretical in-transit losses when the comparison ofnet volume onboard at standard temperature oncompletion of loading is compared with the netvolume onboard prior to the commencement ofdischarge

● Emptying and filling losses. This is particularlypertinent where a part discharge may take place intoa lightering vessel or barge

● Additional losses which may occur as a result ofcrude oil washing.

The third and the fourth items become apparent whenaccounting for volumetric losses on outturn.

Various factors including permutations of tankerdesign, cargo density, Reid vapour pressure, cargotemperature, ambient temperature and general weatherconditions, may combine to cause a release of gassesand an increase in pressure within the cargo tankswhich, combined with the inert gas pressure, maycause venting through the pressure vent valves andconsequent loss of product.

Losses during dischargeThe largest volumetric losses are likely to occur whenthere is transfer from one container to another. Thismeans that quite large losses can occur when pumpingthe cargo from the ship to the shore. Where lightering is

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involved there will, inevitably, be a greater risk ofvolumetric losses between the ocean carrying ship andthe shore tanks. Where COW is performed, thepotential for volumetric losses is greater since thecargo is being formed into a high pressure spray andpartially atomised.

The shore installationWhen assessing a claim for short delivery of an oilcargo, the ship’s calculation and figures arescrutinised. It is equally important to examine the shorecalculations at both the loading and discharge ports. Asmentioned earlier, the carriers liability does not extendbeyond the ship’s manifold, and claims for apparent oillosses can sometimes be resolved by recalculation ofthe shore figures. The cargo interests should be askedto provide full details of the shore installation including aplan showing all the storage tanks and the interconnecting pipelines as well as the position of isolatingvalves. They should be able to verify the maintenance ofall their equipment and demonstrate that, for instance,all the isolating valves were tight and properly operatingat the time of discharge. They should also be asked todemonstrate that the storage tanks were properlycalibrated and show that the calibration was accurate.In some oil installations the accuracy of the tankcalibrations may be doubtful particularly if they are ofolder construction or built on unstable sites. A smallmeasurement inaccuracy may correspond to asubstantial change in volume. Temperaturemeasurements should also be closely considered:temperature gradients may exist when oil is stored in alarge tank and in certain climatic conditions there maybe significant variations in the temperature within thetank. In a cold wind, there may be a horizontaltemperature gradient as well as a vertical gradient. Inmany countries the measurements taken at the time ofcustody transfer are witnessed by customs officials andif appropriate, the official customs documents shouldbe produced.

Oil contamination claimsMany oil shortage claims arise from the presence ofexcessive quantities of water found in crude oil cargoesat the discharge port after settling out during thevoyage. Oil contamination may occur in petroleumproducts but a cross contamination between twogrades of crude oil would, in most cases, not lead to acargo claim. Crude oil cargoes are regularly blendedbefore refining and generally for a cargo contaminationto arise, a large cross contamination would need to takeplace. This is not true of all grades of crude as there area few which have particular properties and which mustnot be contaminated in any way.

Many modernrefineries, designed forthe reception ofcargoes carried by seahave desalinationfacilities in order toprotect the distillationcolumns and refineryequipment fromexcessive corrosion.Such facilities,however do not alwaysexist. The presence ofwater in certain crudeoil cargoes may also

cause emulsions to form with the hydrocarbons. This inturn may cause ROB volumes to be excessive andpossible sludging of land tanks if efficient waterdraining is not carried out.

It is quite possible that any alleged contamination couldhave taken place ashore before loading. A prudentowner is therefore recommended to protect his interestby ensuring that a ship’s staff take cargo samples fromeach tank after loading and at the ships manifold duringloading, as a matter of routine, so that hard evidence isat hand to refute claims of this kind. Contaminationclaims are more likely to occur in the white oil tradeswhere it is common for a number of grades to becarried simultaneously. As many as eight or ten gradesare commonly carried simultaneously and on a modernpurpose-built product carrier, fitted with deep wellpumps and dedicated loading line, it may be possible tocarry a different grade in each tank with completesegregation.

Aside from leakage which may occur between cargopipelines or cargo tanks and which may result incontamination, the most likely cause of a product beingoff specification is failure to properly prepare the tank orassociated pipelines after a previous incompatiblegrade.

Precautions before loadingEvery care should be exercised to ensure that propertank cleaning procedures are rigorously carried out andthat tank coatings are in a suitable condition for theintended cargo. Particular care should be taken toensure that all traces of the previous cargo are removedin the cleaning process.

When carrying multigrade cargoes, effectivesegregation is a prime importance. When preparing theloading plan, allowances must also be made for trimand draft restrictions, it is not uncommon for multigrade

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Appendix:definitions of terms used

API = API GRAVITYPetroleum industry expression for density ofpetroleum liquid expressed in API units. APIgravity is obtained by means of simultaneoushydrometer/temperature readings, equated to,and generally expressed at 60°F. The relativedensity to API gravity relation is:

141.5

Relative density 60°F– 131.5

AUTOMATIC SAMPLERA device installed for indicating the level ofproduct from a location remote to the manualgauge site.

BARRELPetroleum industry measurement unit equal to42 US gallons.

CLINGAGEThat oil remaining adhered to the inner surfaceand structure of a tank after having beenemptied.

CRUDE OIL WASHING (COW)The technique of washing cargo tanks of oiltankers during the discharge of crude oilcargoes.

DENSITYThe density is the mass per unit volume at aspecified temperature used to determineweight for a volume at a standard temperature.

DIPIs depth of liquid = to American expression:gauge.

FREE WATERThe quantity of water resulting frommeasurements with paste or interface detector,i.e. not entrained water present in oil.

GAUGE REFERENCE HEIGHTThe distance from the tank’s strike point to thebench mark or reference point.

GROSS OBSERVED VOLUME (GOV)The total volume of all petroleum liquids,excluding S&W, excluding free water, atobserved temperature and pressure.

cargoes to be loaded in more than one port and forseveral discharge ports to be involved. In some cases,additional cargo may be loaded during the voyage afterthe discharge of other products. Careful planning isadvisable taking into consideration the quantity of cargoto be loaded and discharged, draft, trim and stressconsiderations as well as the consumption of water andfuel.

Before loading, all those concerned should have a clearknowledge of the intended loading plan and thepipelines and valves must all be carefully set anddouble-checked. Because product cargoes generallyhave a low specific gravity, it is likely that the ship maynot be loaded down to her marks even with all cargotanks filled to the maximum permissible. When loadingfor a voyage which entails passing through areas wherehigher sea temperatures are expected to beencountered, it is advisable to take into account theexpansion of the cargo which will occur as a result ofthose higher temperatures.

During the loading of sensitive products it is commonfor ‘foot samples’ to be loaded and for samples to betaken and analysed before the rest of the product istaken onboard. When carrying multigrades it is anexcellent practice to have as many samples of the cargoas possible taken at various stages of the loading anddischarge, including samples taken from theshorelines. If claims for contamination arise, theanalysis of such samples will often identify the source ofthe problem and may assist the shipowner in rejectingliability.

A more detailed article on the sampling of liquidcargoes is included later in this section, and a carefulstudy of that article is recommended.

ConclusionIf the following points are borne in mind by owners andmasters there will be a much greater chance of successwhen defending oil cargo claims.

● Careful attention should be paid to all onboardsurveys when loading and discharging with a view toavoiding ‘paper losses’

● After discharge try to ensure that a dry tankcertificate is issued showing all cargo remainingonboard to be unpumpable and endorsed to confirmthat the ships equipment was working correctly

● Employ properly qualified surveyors and protest if itcan be demonstrated that a surveyor employed bycargo interest is not qualified or lacks experience.

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GROSS STANDARD VOLUME (GSV)The total volume of all petroleum liquids andS&W, corrected by the appropriatetemperature correction factor (Ct1) for theobserved temperature and API gravity, relativedensity, or density to a standard temperaturesuch as 60°F or 15°C also corrected by theapplicable pressure correction factor.

LOAD ON TOP (LOT)The concept of allowing hydrocarbon materialrecovered during tank washing to becommingled with the next cargo.

NET OBQOBQ less free water in cargo, slop tanks andlines, and water in suspension in slop tanks.

NET OBSERVED VOLUME (NOV)The total volume of all petroleum liquids,excluding S&W, and free water at observedtemperature and pressure.

ONBOARD QUANTITY (OBQ)Cargo tank quantities of any material onboard aship after de-ballasting immediately prior toloading. Can include oil, oil/water emulsions,water, non-liquid hydrocarbons and slops.

REMAINING ONBOARD (ROB)Cargo or residues remaining onboard ship afterdischarge.

SEDIMENT AND WATER (S&W)Non-hydrocarbon materials which are entrainedin oil. Material may include sand, clay, rust,unidentified particulates and immiscible water.

SHIP’S COMPOSITE SAMPLEA sample comprised of proportional portionsfrom running samples drawn from each tank onthe ship.

SHIP FIGURESStated volume extracted from ship’s calibrationtables based on measurements taken fromcargo tanks.

SLOP TANKA tank into which the tank washings (slops) arecollected for the separation of the hydrocarbonmaterial and water; the recovery most oftenbecoming LOT (load on top).

TOTAL CALCULATED VOLUME (TCV)The total volume of the petroleum liquids and

S&W, corrected by the appropriatetemperature correction factor (Ct1) for theobserved temperature and API gravity, relativedensity, or density to a standard temperaturesuch as 60°F or 15°C and also corrected by theapplicable pressure factor and all free watermeasured at observed temperature andpressure. (Gross Standard Volume plus freewater).

TOTAL DELIVERED VOLUME (SHIP)It is defined as the Total Calculated Volume lessROB.

TOTAL OBSERVED VOLUME (TOV)The total measured volume of all petroleumliquids, S&W, and free water at observedtemperature and pressure.

TOTAL RECEIVED VOLUME (SHIP)It is defined as the Total Calculated Volume lessOBQ.

ULLAGE (OUTAGE GAUGE)A measurement taken from the gauge referencepoint to the liquid level.

VOLUME CORRECTION FACTOR (VCF)The coefficient of expansion for petroleumliquids at a given temperature and density. Theproduct of the petroleum liquid volume and thevolume correction factor, equals the liquidvolume at a standard temperature of either 60oFor 15oC.

WATER (DIP) GAUGEa) The depth of water found above the strikepoint, orb) To gauge for water.

WATER FINDING PASTEA paste, which when applied to a bob or rule, iscapable of indicating the water productinterface by a change in colour at the cut.

WEDGE CORRECTIONAn adjustment made to the measurement of awedged shaped volume of oil, so as to allow forthe vessel’s trim.

WEIGHT CONVERSION FACTOR (WCF)A variable factor related to density for use toconvert volume at standard temperature toweight.

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Samples and samplingin the carriage of liquidbulk cargoesThe period of the carriers’ responsibility for liquid bulkcargoes is essentially the same as that for bulk orgeneral cargo. Under the Hague and Hague VisbyRules, the period extends from the time when the goodsare loaded until the time they are discharged andincludes the loading and discharging operations. Underthe Hamburg Rules, which came into effect 1992, thecarrier, his servants and agents will be responsible fromthe time the goods are received by them at the port ofloading until the time the goods have been delivered atthe port of discharge.

Having received the goods, the carrier, the master oragent is required to issue to the shipper a bill of ladingshowing, among other things, the apparent order andcondition of the goods as received onboard. With theexception of cargoes carried in the deep tanks of linervessels, which may be loaded by the shipper anddischarged by the consignee, most loading anddischarging operations with bulk liquid cargoes areperformed by the actual carrier. There may be differentpractices in the loading and discharging ports andthese together with the nature of the cargo areimportant factors. Most bills of lading include the words“shipped in apparent good order and condition”. Canorder and condition be ascertained by ship’s officerswhen loading takes place via a closed pipeline system?

The answer lies in an effectivesampling system!By reason of the wide variety of liquid cargoes that arecarried and the vastly different types of ships involved, itwill be appreciated that the subject of sampling is a verywide one. This article is confined to the generalprinciples of how to ascertain the apparent order andcondition of goods when they are shipped and, just asimportantly, how to preserve the evidence.

Many parcel-tanker owners have issued instructions totheir masters to sample each type of cargo at the ship’smanifold on commencement of loading, after the firsttest-load (so called ‘first run’ sample) and from theship’s tank after completion of loading. Such samplesare numbered and entered in a special sample log bookAn additional advantage of this procedure is that theship’s officers who attended the sampling, or whoactually drew the samples, are available for questioningat the port of discharge. It is so often the case thatunilateral sampling by shippers at the loading port is not

witnessed by ship’s officers and samples allegedlydrawn from ship’s tanks are handed to the ship’s staffjust prior to departure. These problems confirmabsolutely the need for a joint sampling procedurebetween shippers and carriers and carriers andconsignees.

Owners are strongly recommended to instruct theirship’s officers that whenever they are in doubt as to theapparent good order and condition of a liquid bulkcargo, they should notify both the shipper and theClub’s correspondents so that expert advice may besought and samples analysed at the loading port. Incase of serious doubt as to the condition of the cargothe results of the analyses should be awaited beforeany bills of lading are signed.

It should be emphasised that as with bulk or generalcargo, the description on the bill of lading relates to theexternal and apparent condition of the goods. Claimson liquid bulk cargoes often involve the question ofquality, which is not usually apparent and these claimsmay be based on a detailed analysis which the carrierhas no means of checking. Furthermore, in the majorityof instances, the ship’s staff cannot question thecondition of a product upon loading, except perhapswhere the presence of free water, haziness or dullappearance, the presence of a strong foreign odour oran obvious deviation in the colour of the product isreadily apparent.

It is therefore important that samples carefully taken atthe time of loading and prior to discharge are trulyrepresentative of the condition of the cargo and areavailable in the event that any dispute arises. Whereloading port samples have been drawn and retainedonboard, any uncertainty about the quality of the cargoat the time of loading can be clarified at relatively lowexpense.

The shipper however, is in quite a different positionbecause apart from the sampling and analysis whichtakes place prior to loading he may consider itnecessary to take ‘first run’ samples from the ship’stanks at the commencement of loading operations andsuspend loading until analysis is attained. The ship’sstaff may not be involved or even informed about theresults of this analysis. Bona fide shippers will usuallyprovide this information, however, and will require theship to discharge the ‘first run’ of cargo if this analysisshows it to be ‘off specification’.

When loading operations are resumed it should not beassumed that the ‘first run’ of cargo will be in goodorder and condition. This may not necessarily be thecase as the shipper may have found the product to be

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only slightly off specification and have decided to‘blend’ the cargo during subsequent loadingoperations. Furthermore, water may be introduced intothe product via the installation’s pipeline system withoutthe ship’s staff being aware of it.

The importance of carefully cleaned tanks, compatibletank coatings, well maintained pipe lines, heating coils,valve systems, hoses and pumps cannot be too stronglystressed and some brief comments on the subject ofhoses and pumps may be helpful.

When cargo is loaded by shippers and discharged byconsignees, it is their responsibility to ensure that thehoses and pumps supplied are suitable for the productconcerned. The importance of sampling firstly, after the‘first run’ of cargo has been loaded, secondly, aftercompletion of loading and thirdly, prior to discharge, isparamount in order to establish by analysis whether ornot any alleged damage or contamination could havebeen caused as a result of the use of unsuitableequipment supplied by the shipper or consignee, or bydefects in the ship’s loading system.

It must also be emphasised that there is duty on theship’s crew to assist shippers and/or consignee withthe proper connection of hoses and to ensure that, inthe case of loading over the top, hoses are placed in theproper tanks. The crew should also ensure that wherethe ship’s integral piping system is involved, the cargois directed to the correct tank during loading, and thatthe lines used during loading and discharging areproperly isolated to avoid contamination with otherproducts onboard.

Sale contractsThe condition of liquid bulk cargoes when shippedshould be in accordance with either the specification inthe contract of sale, or the usual grade specificationsused in the trade. The carrier is not a party to thecontract of sale and cannot be expected to haveknowledge of the specification that in most cases relateonly to quality.

Certain limited quality descriptions such as ‘clear’,‘colourless’ etc. may be apparent upon visualinspection of samples and the presence of water canusually be detected by an experienced ship’s officer.However, the wide variety of products, frequentlyreferred to only by trade names or codes, makes itdifficult, if not impossible, for ship’s officers to detectother than the most obvious deviations in the conditionof the cargo.

Sale contracts, while regulating the relationshipbetween seller and buyer, also have some bearing on

the carrier’s position. They usually require certainsampling procedures to be carried out and theappointment of an independent surveyor to certify thefitness and cleanliness of the ship’s tank and pipelines.Many standard vegetable oil contracts requiredischarging samples to be drawn in the presence ofboth seller and buyer’s representatives and analysedby an independent chemist. Almost all oils and fats aresold subject to such sampling and analysis but thecontracts rarely provide for the carrier to be given suchsamples.

Evidence of the condition of a liquid bulk cargo onloading is therefore of paramount importance. Claimslodged at the port of discharge have frequently beendefeated as a result of analysis of loading samples.

Most sale contracts provide for the change of ownershipof the cargo to take effect at the time of loading onboardship and for a bill of lading to be obtained from thecarrier It is therefore important for both seller and carrierto have evidence of the condition of the cargo at thattime. The carrier’s responsibility may howevercommence at an earlier time depending on the momentof taking charge of the cargo.

The sampling activities of shipper and buyer often leadship’s officers to believe that nothing is required of them,as the carrier’s position has been sufficiently protected.This however is not always the case.

The carrier must take an active part in the samplingprocedures especially at the loading port and must seethat his interests are properly protected.

SamplingThere are several other important reasons why samplesshould be taken during loading of bulk liquid cargoes,i.e:

● To enable protest to be made to the shipper if theproduct loaded is not in apparent good order.

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● To enable the loading operation to be followed in allits stages.

● To provide evidence should the ship’s tank coatingsbe found damaged upon discharge.

● To enable the carrier to provide evidence shouldlocal authorities lodge pollution claims against theship.

● To enable the specific gravity and temperature of thecargo to be established.

● To investigate subsequent claims against the carrierfor admixture or contamination.

Sampling prior to loadingShippers of liquid bulk cargoes will not in most casesallow the carrier to take samples from shore tanks, roadtankers, barges or tank wagons, particularly when theshippers are responsible for the loading of the cargo.

It should also be particularly noted that there are manyareas of the world where large consignments ofvegetable oils are delivered alongside by a wide varietyof road tankers, barges or rail tank wagons. With roadtankers and rail tank wagons the product is usuallydrained into the shore containers before being pumpedonboard. Invariably these tankers are used for a varietyof commodities including both vegetable and mineraloils and their cleanliness should not always beassumed. Indeed, shippers do not always check thesuitability of such wagons until they arrive alongside inloaded condition where they are sampled by theshippers’ inspectors. It is also common practice in thistrade for shippers to ‘borrow’ from each other to makeup the total quantity loaded into a particular ship, so thecargo may consequently be of variable quality andcondition. In the case of loading from tank barges,sampling takes place prior to loading into the ship. Evenif the ship’s officers are provided with such samplesthey have no control over how they were drawn andthere is no certainty about when or from where theywere taken.

Sampling during loadingThe first requirement is that on commencement ofloading samples are taken from the ships manifold or‘first run’, samples from the ship’s tanks, even thoughthe loading operation may have to be suspended whilethis is done. It is essential that shipper’s inspectors takepart in this sampling procedure and that the samplesshould be split between the parties. Whenever loadingoperations are interrupted and hoses, pumps or linesystem are changed, sampling of the relevant ship’stanks before and after the changeover will be

necessary, unless it is certain that hoses, lines andpumps have been previously used for the same product.

On completion of loading, a representative sample fromeach tank should be taken. In the case of a parcel tanker,each consignment should be similarly treated. Shipper’sinspectors frequently take ‘first run’ samples on theirown initiative and will usually make up compositesamples of all tanks after completion of loading.

Loading port samples other thanthose taken by the carrierSamples are sometimes handed to the ship’s staff to bedelivered to the consignees in accordance with thesellers contractual obligations. In such cases ship’s staffare unaware how or where such samples were obtainedand it is rare for the ship to be provided with a duplicateset for its own use. The origin of such samples isuncertain and their labels often bear vague descriptionssuch as ‘average shore tanks’ ‘average tank trucks’‘average head line’ etc. These samples whether relatingto vegetable oils, mineral oils, or petrochemicals, maybe samples drawn before and/or during and/or afterloading, single or duplicate, sealed or unsealed andeither against a receipt or not. The carrier has no controlover the drawing of such samples and in many casesanalyses of them are in conformity with the requiredspecification whereas the cargo on arrival is not. At theport of discharge such shipper’s loading samples arecollected by inspectors appointed by the shipper orconsignees who may also measure and sample theships tanks. Samples drawn at the loading port jointly byship’s staff and shippers representatives may then serveto prove that the samples handed to the ship’s staff fordelivery to consignees may not represent the truecondition or quality of the cargo.

Sampling before dischargeOn arrival at the discharge port and immediately tankullages and temperatures have been carefully checked,samples should be taken of all cargo onboard. Thissampling is usually carried out by the consignee’ssurveyor and the procedure should be attended byship’s officers. It is usual to take top, middle, lower, andbottom samples, depending upon the product. In thecase of cargo that remains homogeneous during thevoyage, such samples may be mixed into a compositesample with the largest proportion coming from themiddle depth of the tank. It is also desirable to use awater finding instrument to establish if water is present.

In the case of edible oils and animal oils/fats, bottomsamples should always be drawn to check for sediment.These bottom samples must be kept in separate jars,sealed and properly labelled for identification. It must be

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emphasised that sediments, if any, should always beregarded as belonging to the particular consignmentinvolved.

With many products it is the practice to defercommencement of discharge until analysis of thesamples has been completed. If the receivers indicatethat the cargo does not conform to the requiredspecification, the master should immediately requestthe local UK Club correspondent to arrange for theattendance of an independent surveyor and for theanalysis of loading samples.

Sampling proceduresBecause of the wide variety of liquid cargoes carriedand the different methods of loading only general adviceon sampling can be given.

Cargo sampling is a difficult process and one thatrequires most careful attention. It should be emphasisedthat each sample must be representative of the productconcerned. Continuous sampling at the ship’s manifoldin order to obtain a so-called ‘ship’s rail composite’sample, though a time consuming procedure, may be ofvalue in the case of homogeneous cargoes where tanksamples taken prior to commencement of dischargehave shown the product to be satisfactory at the time theship arrived. A sample of the first cargo arriving at theship’s manifold, a ‘first run’ sample from the ship’s tankand a sample or set of samples drawn from the tank oncompletion of loading are the most important. In thechemical (parcel) trade, running samples during the first

five minutes of loading are sometimes also drawn. Theobject of all these sampling operations is to obtain amanageable quantity of cargo, the condition andproperties of which correspond as closely as possibleto the average condition and properties of the parcelbeing sampled.

Most liquid samples can be stored in glass jars withscrew type caps or cork plugs. In most cases samplesdo not each have to be larger than half a litre (500cc).

The importance of cleanliness cannot be too stronglystressed. All sampling work should be done with cleanhands and where protective clothing is necessary, as inthe case of toxic products, clean gloves of a suitablematerial should be used. The apparatus used should beof a suitable material, e.g. stainless steel, which doesnot react chemically with the cargo being sampled.Various types of sampling bottle can be used,particularly in large tanks but should glass bottles beemployed, great care should be taken to avoidbreakage.

With edible oils, where smell and flavour is important inquality assessment, scrupulous cleanliness is essentialand the sampling devices should be thoroughly washedwith hot water and soap and rinsed with hot waterbefore use. All sampling equipment should beprotected from the weather, rain, dust, rust, grease,etc., and before the sample is divided into suitable glassjars, the outside of the sampling apparatus should bewiped clean.

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When sampling from the manifold or pipeline, greatcare should be taken to ensure that the sampling cockthrough which the product is drawn is absolutely clean.This method of sampling is most difficult and must becarefully supervised to ensure that both shipper andcarrier obtain a part of the same representative sample.It is important that when samples are being taken by thismethod, a constant rate of flow of the product isinvolved. If there is a variation in the flow rate, thesampling cock must be carefully regulated to ensurethat the full sample is taken at a constant rate.

Certain products, such as those reacting dangerouslywith water and/or air and corrosive liquids or liquefiedgases, cannot be sampled by normal means. It may alsobe dangerous to keep samples of some products fortoo long as they become unstable.

Labelling of samplesAll samples jointly taken should be properly labelledand sealed and identical sets should be kept by allparties. Should shippers refuse to seal the samplesjointly, then an appropriate entry should be made in thelog book. They should be unilaterally labelled andsealed by the ship’s staff and/or the independentsurveyor representing the carrier. The samplesthemselves must, of course, be identical to those takentogether with the shippers and the latter must benotified in writing immediately, to confirm the jointsampling and record their refusal to seal these identicalsamples jointly with the carrier.

The attention of owners is also drawn to the undesirablepractice in many ports of the chief officer being asked tosign paper labels which bear the names of the ship, theshippers, the product, the ship’s tank, the date andplace of sampling, a seal number (such as the one toappear later on the wax seal) and the signature ofshippers’ inspectors before the loading operationshave been completed or sometimes even before theyhave started. These labels are later attached to thesample containers after they have been filled andclosed.

It cannot be too strongly emphasised that the only wayto be certain that the proper label is put on the propersample container is for the ship’s staff to participate inthe whole procedure of sampling and sealing and toinsist that the sealing and the labelling should takeplace onboard the ship. All labels should be properlydated and should indicate the local time when theywere drawn, name of the product and its destination,the name of the shippers and whether the sample wasdrawn conjointly with them. The label should alsorecord the quantity, tank number, the tank ullage and

temperature, the bill of lading and voyage number andwhether it is a manifold, pipe line, ‘first run’ or ‘average’ship’s tank sample after completion of loading. Caremust be taken that all these necessary details willremain legible by the use of permanent washable ink.Having signed the labels, the ship is entitled to retain aset of the samples.

Storage of samplesSamples should be stored in a dark, well-ventilatedplace where daylight cannot enter and away fromsources of heat, from living quarters and foodstuffstorerooms. Edible oils and chemicals should be storedseparately. Samples should be contained in clean, dryand airtight containers, preferably of glass, tinned steelor a plastic material which will not become affected bythe contents. They should be closed with corks orsuitable plastic stoppers.

A sample log book should be maintained recording thesample number, the sampling date, place, ship’s tank,quantity and kind of product, name of shipper and placeof shipment, name of consignee and place ofdischarge, where stored onboard, and notes ondisposal. It is suggested that samples be retained for aperiod of three months after the ship has discharged.

The carriage of liquid bulk cargoes requires carefulsampling as an essential part of the operation. If this isperformed in accordance with the procedures set out inthis article it will be of considerable assistance inrepudiating unjustified claims brought against the ship.

Sampling instrumentsVarious types of instruments designed to facilitatesampling are obtainable in most major ports. They maybe made of glass, stainless steel, aluminium, etc., sothat a choice of material is available to ensure that theinstrument is compatible with the cargo carried. It isgenerally advisable to avoid instruments made ofcopper or copper based alloys.

Sampling instruments should be simple, robust andeasy to clean. On the following pages a number ofinstruments are shown in diagram form together withtheir descriptions. The Association is grateful to theBritish Standards Institution for allowing material fromB.S.627 to be reproduced.

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Fig 3. Go devil’ sampling bottleThe ‘Go devil’ sampling bottleconsists of a bottle, heavilyweighted at the bottom,approximately 12" (300 mm) long,3" (75 mm) body diameter andapproximately 1" (25 mm) bodydiameter and approximately 1" (25mm) neck diameter, with a chainattached. On being placed in oil in atank it drops so quickly that it doesnot begin to fill with oil until itreaches a fixed position

Fig 4. Bottom sampler or zonesamplerThe bottom sampler or zonesampler is suitable for withdrawingbottom samples or zone samples atany level from tanks of liquid oil. Towithdraw a bottom sample theapparatus is attached to a cord orchain and lowered empty to thebottom of the tank, when thecentral spindle valve automaticallyopens and the container fills fromthe bottom. On withdrawal of thesampler the valve automaticallycloses again To withdraw samplesat any level the apparatus islowered empty to the required leveland then, by means of an additionalcord attached to the top of thecentral valve spindle, the valve maybe opened and the container filled.When the sampler has filled, thevalve is allowed to close and thecontainer is withdrawn

Sampling instruments for bulk oil shipmentsand some other liquid bulk cargoes

Fig1. Sampling bottle or canThe sampling bottle is suitable forsampling large ships and tanks ofliquid oil. It consists of a bottle ormetal container, which maybeweighted, attached to a handlelong enough to reach to the lowestpart to be sampled. It has aremovable stopper or top to whichis attached a suitable chain, pole orcord. This device is lowered to thevarious desired depths, where thestopper or top is removed and thecontainer allowed to fill

Fig2. Sampling tipping dipperThe tipping dipper consists of acylinder approx. 6" (150 mm) longand 2" (50 mm) in diameter,carrying an extension with a hole atits closed end and a stout wirehandle at the open end; the handlecarries a small metal catch and arope. The cylinder is inverted in theposition shown on the left, andmaintained in that position by theinsertion of the catch into the hole,and then sunk into the oil in thetank; at the required depth the ropeis twitched to release the catch,where upon the cylinder rightsitself and becomes full of oil

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The production and use of biofuels as transport fuelshas increased dramatically in recent years. A number oflegislative reforms are mandating the integration offuels derived from renewable sources into the currentfuel infrastructure. However, the introduction of biofuelshas not been without problems and indeed there is alarge amount of research still ongoing into theproperties of biofuels and how they behave whenblended with conventional fossil fuels. This article willdiscuss some of the issues surrounding theintroduction of biofuels into the present fuel system withparticular focus upon the potential implications forthose involved in the transportation and storage ofthese products.

Legislative targetsBiofuels were originally seen by many as an answer tothe problems of increasing greenhouse gas emissionsand global warming. Unlike transport fuels derived fromcrude oil, such as diesel and gasoline, biofuels areproduced from renewable sources; that is, sources thatcan be replenished at a rate comparable to or fasterthan the rate at which they are consumed by humans.Fuels produced from agricultural crops such as corn,wheat, rapeseed and soybean, which could be quicklyand easily replenished and, in theory, should have anegative overall impact in terms of carbon dioxideemissions, seemed an ideal solution for governmentsfacing increasingly difficult decisions with regard to thelinks between pollution and climate change, andlegislative targets were quickly put in place mandatingthe integration of biofuels into the current transport fuelinfrastructure.

However, it was not long before serious questions wereraised with regard to the environmental credentials and

overall sustainability of the commercially availablebiofuels. Issues included the use of crops which wouldnormally be used for food being put into biofuelproduction, the questionable carbon dioxide emissionssavings when considering the overall productionprocess (‘wells to wheels’), deforestation to make wayfor biofuel crop plantations and the use ofenvironmentally harmful fertilisers and pesticidesemployed in growing the crop feedstock. Indeed it wassuggested by some parties that biofuels could in realitybe causing more harm than good to the environment.

Amid these growing concerns, the UK Government hasrecently decided to amend the targets set out in theRenewable Transport Fuel Obligation (RTFO), adirective aimed at reducing greenhouse gas emissionsfrom road transport. The RTFO requires that by2013/14, 5% by volume of all fuel sold in UK forecourtsis to come from renewable sources, with intermediatetargets of approximately 3.5%, 4% and 4.5% for theperiods 2010/11, 2011/12 and 2012/13 respectively.

These targets represent a slowdown in the requiredbiofuels targets, but they are likely to be reviewed in

Biofuels: Marine transport, handling andstorage issues

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2013/14 in order to assess the progress of the UKRTFO in complying with the wider EU initiative toreduce carbon emissions, the Renewable EnergyDirective. This directive was recently reviewed andagreed in December 2008, and mandates that by 2020,10 per cent of all automotive fuel consumption byenergy content should be sourced from renewableenergy sources.

Amid all the uncertainty, it appears likely that theworldwide push for increasing biofuel use as a meansof reducing overall carbon dioxide emissions willcontinue, and one can reasonably expect the biofuelsmarket to continue to grow. Much of the biofuel isshipped internationally by sea. For example, first halffigures for the 2008/2009 period indicate that 670million litres of biofuels were supplied to the UKtransport market. Only 8% of the biofuel supplied wasproduced from within the UK, such that 92%(approximately 616 million litres) of biofuel wasimported. A recent report by Pike Research estimatedthat the global biodiesel and ethanol markets are likelyto reach US$ 247 billion in sales by 2020, up fromUS$ 76 billion in sales predicted for 2010.

In order to meet the necessary targets, the quantity ofbiofuels shipped both into the UK and worldwide islikely to increase, and it is therefore important for thoseinvolved in the carriage of biofuels to understand theissues that need to be considered if these products areto be carried safely, without risking damage to either theship or the cargo.

Current biofuelsThere are presently two main classes of biofuels inwidespread use; biodiesel (or more correctly, FAME)and bioethanol. The two are very different in theirproperties and therefore have different issues toconsider if they are to be safely shipped, handled,stored and used. Each will be considered in turn.

FAME/BiodieselBiodiesel is a fuel derived from vegetable oils or animalfats, although the term ‘biodiesel’ is too vague adescription and we therefore use the more correctterminology, Fatty Acid Methyl Esters (FAME), whendiscussing these fuels. FAME is the product of reactinga vegetable oil or animal fat with an alcohol (methanol, apetrochemical which is generally derived from naturalgas or coal) in a process known as transesterification.When compared to conventional diesel derived fromcrude oil, vegetable oils and animal fats generally havehigher viscosities (which means they are more difficultto pump and store without heating) and are more

unstable (which means they are more likely to degradeduring storage, handling and end-use). Thetransesterification process brings the properties of theraw materials closer to those of a conventional diesel,making the product more suitable for use as a roadtransport fuel. However, whilst the FAME produced canbe used neat as a fuel, it is more commonly blendedwith conventional petroleum diesel for use in dieselengines.

The ASTM has described a system of nomenclature fornaming FAME/diesel blends (see ASTM D6751). PureFAME is denoted B100, standing for 100% ‘biodiesel’.Other common blends include B5 (5% ‘biodiesel’ and95% conventional diesel), B7 (the EN590 Europeandiesel standard allows up to 7% by volume FAME indiesel) and B20 (20% ‘biodiesel’ and 80%conventional diesel). In the UK, a major supermarketchain has introduced B30 (30% ‘biodiesel’ and 70%conventional diesel) pumps onto a number of theirforecourts (Motor Consult Update November 2008).However, this fuel is not currently governed by anystandards and is not approved for use by many of themajor automobile manufacturers.

Raw materials for FAME production

A wide number of raw materials can be used for theproduction of FAME, including palm oil, coconut oil,rapeseed oil, soybean oil, tallow and used cooking oils.A general FAME cargo might be the product ofprocessing any one of these raw materials, or mayindeed be a mixture of FAMEs produced from differentraw materials. Each raw material would give FAME of adifferent chemical composition, with correspondinglydifferent characteristics. For example, if we compare aFAME derived from palm oil (PME) with a FAMEderived from rapeseed oil (RME), it is possible to noticean immediate visible difference between the two –namely that at normal UK winter temperatures the PMEis likely to be solidified whereas the RME will be a liquid.It is the chemical composition of the raw materials andthe FAMEs produced from them that explains many ofthe different characteristics displayed.

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One of the most important chemical characteristics ofFAME is the structure and composition of the fatty acidmethyl ester groups, which will be determined by thefatty acid components of the raw material used in theproduction process. Pictorially, we can see a differenceif we look at the structures of two different fatty acidsbelow – one a saturated fatty acid and one anunsaturated fatty acid – the saturated fatty acid has a‘straight chain’ of carbon atoms (circled in red)whereas the unsaturated fatty acid has, in this case,two ‘double bonds’ present in the hydrocarbon chain.These are circled in green and result in ‘kinks’ in thehydrocarbon chain:

Myristic Acid – A saturated fatty acid

Linoleic Acid – An unsaturated fatty acid

FAME species which are composed of a relatively highproportion of saturated fatty acid methyl esters, forexample, palm oil derived FAME (denoted PME) will ingeneral be relatively stable to unwanted degradationreactions, but will have poorer cold temperatureperformance. FAME species which are composed of arelatively high proportion of unsaturated fatty acidmethyl esters, for example, soybean oil derived FAME(denoted SME), will display markedly differentbehaviour, typically having improved cold temperatureproperties in comparison to PME, but being less stableto degradation reactions. The reason for the improvedcold-temperature behaviour displayed by the FAMEspecies high in unsaturated fatty acid methyl esters isthat for every double bond in the hydrocarbon chain andassociated kink in the molecule, the individualmolecules cannot pack as closely together therebyreducing intermolecular forces and correspondinglydecreasing the melting point. However, it is thepresence of the double bonds in the unsaturated FAMEspecies that infers the greater degree of instability uponthe molecules – the double bond sites render themolecule prone to oxidative degradation.

The presence and composition of other chemicalconstituents are also important. For example, FAMEswith high levels of vitamin E are thought to be morestable to unwanted oxidative degradation reactions.Recent research reported in Biodiesel magazine hasidentified the formation of sediments in stored B5 andB20 blends. Analysis of the sediment componentssuggests that they originate from the oxidation of

unsaturated fatty acid methyl ester components ofFAME. However, the addition of antioxidants to the neatFAME prior to blending was found to prevent sedimentformation. Vitamin E is a natural antioxidant whichwould appear to prevent the occurrence of suchunwanted oxidation reactions.

FAME problems

Water contamination: A major problem with regardto the carriage of FAME by sea is the issue of watercontamination. FAME is a hygroscopic material, whichmeans that is will absorb water from its surroundingenvironment, including the atmosphere. This rendersFAME very sensitive to water contamination. The currentmaximum allowable water content in the European EN14214 and American ASTM D6751 FAME standards is500 mg/kg, although often selling specifications arelower (300 mg/kg being a typical maximum watercontent on a sales specification), reflecting the highpotential for water pick-up in this material.

Unlike most conventional diesels, in which any un-dissolved water present will generally settle out over aperiod of time, FAME can hold water in suspension up torelatively high levels (above 1000 mg/kg). Apart fromthe fact this will render the cargo off-specification forwater content, the presence of water can promoteunwanted hydrolytic reactions, breaking down theFAME to form free fatty acids, which can again affectcertain specification parameters for the material – suchspecies are corrosive and may attack exposed metalsurfaces. Additionally, once a certain threshold level ofwater content is reached, water can separate out fromthe FAME, forming a separate (and potentially corrosive)free water phase. The possibility of phase separationoccurring is greater for blends of FAME andconventional diesel.

The presence of a FAME/water interface provides idealconditions for the promotion of unwantedmicrobiological growth, which may in turn lead to filterblocking and corrosion problems. Certain publicationshave referenced the greater degree of biodegradabilityof FAME as a positive factor when dealing withenvironmental spillages. This is indeed correct, but bythe same token this factor means that FAME is

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considerably more prone to microbiological attack thana conventional fossil fuel, with the associated problemsmentioned above. A number of studies have beenperformed in this area which highlight the need forfurther detailed analysis and research into the potentialfor serious microbiological contamination occurring atvarious stages in the biofuel supply chain.

Possible sources of water contamination aboard avessel range from the obvious – sea water ingress orresidues of tank washing operations – to the lessobvious – moisture in an inert gas blanket producedfrom a faulty flue gas generating system, oratmospheric humidity in tanks’ ullage spaces that arenot under a positive pressure of dry inert gas. Despitehaving relatively high flash points, FAME cargos aregenerally carried under a (dry) nitrogen blanket in orderto avoid the potential increase in water due toabsorption of moisture from tank ullage spaces.

Stability problems: FAMEs aregenerally more prone to issueswith regard to their stability thanconventional petroleum diesel.We have mentioned previouslythat certain FAME/diesel blendscan be oxidised to form unwanteddegradation products and that theaddition of antioxidants mayprevent the formation of thesesediments. FAME can degradeunder the influence of air, heat, light and water, anddegradation may occur during transport, storage oreven during end-use. FAME cargoes may displaydifferent levels of stability dependent upon theircomposition and the feedstock(s) used in theirproduction. In general FAME with higher levels ofunsaturated fatty acids, such as soybean and sunfloweroil derived FAME, will be less stable than thosecomposed of higher levels of saturated fatty acids, forexample, palm oil or coconut oil derived FAMEs.

Potential shipping problems include the promotion ofdegradation reactions by trace metals (copper heatingcoils or zinc-containing tank coatings have the potential

to cause deterioration in quality) and thermal stabilityissues if the FAME cargoes are stored next to heatedtanks, for example, bunker settling tanks. Issues with thepromotion of instability by the presence of trace metalsare worse for B100 than for lower biodiesel blends (e.g.B5, B20). Degradation reactions can form insolublesediments and gums, which may increase the viscosityof the FAME, lead to filter blocking or potentially furtherdecompose to other more corrosive species. Thecarriage of FAME under dry nitrogen blankets can alsohelp to prevent unwanted degradation reactions causedby the material coming into contact with air.

Low temperature behaviour: The poor lowtemperature properties of FAME when compared toconventional diesel may give rise to issues where FAMEcargoes are shipped through extremes of coldtemperature. It is possible for certain FAMEs to formwaxy precipitates at low temperatures which will thennot re-dissolve when the product is reheated, althoughthis would not appear to be a common problem.However, there is the potential for FAME cargoesshipped from a warm, humid climate to extremely coldconditions, if the correct measures for heating the cargoare not applied, to form unwanted waxy precipitateswhich may lead to specification failure or pumpingproblems.

As has been mentioned previously, it is generallyrecognised that FAMEs produced from vegetable oilswith relatively high proportions of unsaturated fattyacids, for example, soybean oil, will have better cold-temperature properties than FAMEs produced fromvegetable oils with high proportions of saturated fattyacids, such as palm oil. It is therefore vital that thecorrect heating instructions are issued and followed – anunderstanding of the nature of the FAME will impactupon the necessary heating instructions – this should beborne out by the appropriate research into the origin ofthe FAME and indicated by the results of any pre-shipment testing.

FOSFA International (The Federation of Oils, Seeds andFats Associations Ltd) has now included FAMEproducts in its published heating recommendations:

Oil Type Temperature during voyage Temperature at discharge

Min (oC) Max (oC) Min (oC) Max (oC)

FAME from

Maize/Rapeseed/Soya/Sunflower Ambient Ambient

FAME from

Coconut/Palm/Palm Kernel/Tallow 25 30 30 40

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FAME contamination of jet fuel: FAME is a surfaceactive material and can adsorb onto the walls of tanksor pipelines and de-adsorb into subsequently carriedproducts. This can be an issue where multi-productpipelines or storage tanks are utilised, or where shipscarry jet fuel cargoes after carrying FAME/dieselblends.

The latest DEFSTAN 91-91 jet fuel specification statesthat jet fuel containing less than 5 parts per million(ppm) FAME can be considered acceptable for use,that is, can be considered as being free from anyFAME. Full inclusion of this specification limit into theDEFSTAN 91-91 standard is pending on thedevelopment of a suitable test method to accuratelyidentify FAME in jet fuel at this level. A test programconducted by the Joint Inspection Group (JIG) testedjet fuel dosed with various FAMEs up to 400 ppm andfound no significant affect on specification test results,and the inclusion of the 5 ppm maximum limit into theDEFSTAN 91-91 standard has been granted on thebasis that the aviation industry is working towards a100 ppm maximum FAME content (DEFSTAN 91-91Issue 6).

In May 2008 a number of jet fuel storage tanks atKingsbury supply terminal and Birmingham Airportwere quarantined after it was discovered that samplesof the jet fuel in question contained up to 20 ppm ofFAME. The cause of the contamination is thought tohave been as a result of mixing of jet fuel with B5 dieselin the distillate manifold at Kingsbury terminal. As anindication of the very small quantities needed to causesuch a contamination, the 5 ppm specification limitwould be equivalent to just 1 litre of B5 diesel in 10,000litres of jet fuel.

When vessels may potentially carry jet fuel cargoesfollowing on from FAME or FAME/diesel blends, theJIG recommends that care must be taken with tankcleaning and flushing and draining common linesincluding sea or jetty loading lines. From experience,they suggest that switching from a B5 to jet fuelrequires at least a hot water tank wash (but preferablyalso an intermediate FAME-free cargo) to removeFAME residue. Switching from neat FAME to jet fuelrequires particular care and some advocate at leastthree intermediate (FAME free) cargoes plus the hotwater wash before loading jet fuel (source: JIG BulletinNo. 21).

As 5 ppm is such a low level of contamination, there isthe potential for erroneous results to be produced frominaccuracies in the test methods or incorrect samplehandling. The DEFSTAN 91-91 standard suggests thatthe currently specified method of flushing sample

containers three times for jet fuel samples may not besufficient to remove traces of FAME, which may evenbe transferred from contaminated gloves. This couldpotentially lead to false positive detection of FAME inactually on-specification material, resulting in erroneousclaims being made. It is therefore recommended thatnew sample containers and new gloves are used whensampling jet fuel cargos.

For products tankers carrying multiple products, thedanger of inadvertently contaminating a cargo of jet fuelwith traces of FAME is a very real risk, even if it does notinitially appear that there is any potential for crosscontamination to occur. For example, ultra-low sulphurdiesel meeting the EN590 specification may appear inthe shipping documents as ULSD, which would notimmediately indicate that the product contained anyFAME. However, the EN590 diesel specification allowsup to 7% by volume FAME content. If the ship’s tanksand lines are not completely stripped of all the ULSDprior to loading a cargo of jet fuel, the quantity of ULSDcontaining 7% FAME needed to render the jet fuelcargo off-specification would be very small.

Solvent behaviour: An interesting property of FAMEis its ability to act as a solvent, taking up any organicresidue, dirt or scale that may have accumulated onsurfaces of tanks or pipelines. This can have the effectof cleaning out the dirty storage or pumping systemsbut contaminating the FAME itself, and may lead tosubsequent fouling of filters or pump blockages.

As an indication of its solvent strength, researchersfrom Iowa State University are investigating how thesolvent properties of FAME can benefit militaryapplications, by looking into whether or not certainvarieties of waste generated in-situ in battlefield

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locations will dissolve into biodiesel, and also ifstationary engines can be run on the biodieselcontaining certain levels of dissolved plastics. FAME isknown to attack and quicken the ageing process ofcertain materials, including elastomers (which may beused as seals, valves, gaskets etc.) – materials shouldbe checked for compatibility with FAME and FAME/diesel blends by consultation with the equipmentmanufacturer.

Biodiesel in bunkers: On 15 June 2010 the fourthedition of the marine fuels standard, ISO 8217:2010,was issued. The previous edition of the marine fuelsstandard, ISO 8217:2005, required under point 5.1 ofSection 5 – General Requirements that the fuels to beclassified in accordance with the standard should be“homogeneous blends of hydrocarbons derived frompetroleum refining.” This was interpreted as precludingthe fuel from containing any bio-derived components.During the preparation of the fourth edition of thestandard, the working group committee responsible forthe production of the standard considered the topic ofbiodiesel and the potential for the material to find its wayinto the marine fuel supply chain. It concluded that itwas almost inevitable that as a result of blending FAMEinto automotive diesel that some marine distillates andpossibly even marine residual fuels may contain aproportion of FAME as a result of cross contaminationwithin the distribution system (Source: BunkerworldForum 03/09/2009).

As such, the ISO8217:2010 InternationalStandard nowadditionally requiresunder point 5.4 ofSection 5 – GeneralRequirements that “Thefuel shall be free frombio-derived materialsother than ‘de minimis’levels of FAME (FAMEshall be in accordancewith the requirements ofEN 14214 or ASTMD6751). In the context of this International Standard,‘de minimis’ means an amount that does not render thefuel unacceptable for use in marine applications. Theblending of FAME shall not be allowed.”

Annex A of the ISO 8217:2010 International Standardconsiders the issue of bio-derived products and FAMEsfinding their way into marine fuels in more detail. AnnexA states that notwithstanding the fact that FAME has“good ignition, lubricity properties and perceivedenvironmental benefits”, there are “potentially specific

complications with respect to storage and handling in amarine environment”, including:

● A tendency to oxidation and long term storageissues

● Affinity to water and risk of microbial growth

● Degraded low-temperature flow properties

● FAME material deposition on exposed surfaces,including filter elements.

It is recognised that there are a number of differentsourced FAME products each with their own particularcharacteristics which may impact upon storage,handling, treatment, engine operations and emissions.The standard states that in “...those instances wherethe use of fuels containing FAME is beingcontemplated, it should be ensured that the ship’sstorage, handling, treatment, service and machinerysystems, together with any other machinerycomponents (such as oily-water separator systems) arecompatible with such a product.”

The meaning of a ‘de minimis’ level is expanded upon inAnnex A of the ISO 8217:2010 international standard.It is noted that determining a ‘de minimis’ level is notstraightforward for a number of reasons, including thefact that there is no standardised analytical techniquefor detecting FAME materials in fuel oils and that, inmost cases, sufficient data is not yet available withrespect to the effects of FAME products on marine fuelsystems. For the purposes of the InternationalStandard, for the four grades of distillate fuel (DMX,DMA, DMZ & DMB when clear and bright) it isrecommended that ‘de minimis’ be taken as “notexceeding approximately 0.1 volume %” whendetermined in accordance with test method EN 14078.For DMB when not clear and bright and for allcategories of residual fuels, the standard notes that “...‘de minimis’ cannot be expressed in numerical termssince no test method with formal precision statement iscurrently available. Thus, it should be treated ascontamination from the supply chain system.”

BioethanolBioethanol refers to ethanol produced by thefermentation of renewable sources of sugar or starchcrops. Unlike FAME, bioethanol is a single chemicalcompound, the properties of which are welldocumented and understood. It is a volatile, colourlessliquid which is miscible with water and alsohygroscopic. Ethanol is the alcohol found in alcoholicbeverages and is also commonly used as a solvent inperfumes, medicines and paints. However, the most

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common use for ethanol is as a fuel or fuel-additive.Ethanol for use as a fuel is generally dosed with a‘denaturant’ to render it unsuitable for humanconsumption.

As we have mentioned previously, there has beensignificant experience worldwide in the use of ethanolas a fuel or fuel-additive. In the USA there has beenover ten years successful use of gasoline containing upto 10% ethanol (E10), and in Brazil blends containingup to 85% to 100% ethanol (E85 and E100) arecommonly used in flexible-fuel vehicles. The currentEuropean gasoline specification, EN228, allows up to5% ethanol by volume (E5).

Whilst bioethanol can be produced from a number ofraw materials, including sugar cane, corn and wheat,the raw materials do not impart the same variation inproperties of the end product fuel as is the case withFAME. However, there are still a number of potentialhazards for consideration.

Bioethanol problems

Water contamination: Issues with regard to thecarriage of bioethanol and bioethanol-gasoline blendsinclude the potential for damaging water contamination.We mentioned previously that ethanol is hygroscopic

and highly soluble in water. Small quantities of watercan be dissolved in gasoline/bioethanol blends, but,dependent upon temperature and the gasoline/bioethanol blend ratio, there is a critical threshold levelof water that can be dissolved. Once this thresholdlevel has been exceeded, irreversible phase separationwill occur whereby the water causes the ethanol toseparate from the gasoline, forming an alcohol richwater/ethanol aqueous phase and an alcohol poorgasoline phase. The alcohol rich aqueous phase willcollect at the bottom of the ship’s tank or storage tank.This phase is likely to be highly corrosive and will not beable to be used as fuel. In addition, if such phaseseparation does occur it is possible that the gasolinephase will be classed as Pollution Category Z, whichmeans that it is considered to present a “minor hazardto either marine resources or human health” ifdischarged into the sea from tank cleaning ordeballasting operations and therefore “justifies lessstringent restrictions on the quality and quantity of thedischarge into the marine environment”. Whilst theregulations do not require ethanol to be carried on achemical tanker, ethanol is generally shipped onchemical tankers to maintain the integrity of theproduct.

It should be noted at this juncture that the termsbiodiesel and bioethanol do not appear in the IBCCode. As it is a requirement that the proper shippingname be used in the shipping document for describingany product to be carried which appears in the IBCCode, these terms cannot be used to describe theproducts being carried.

The situation becomes somewhat more confusingwhen we consider how blends of conventional fossilfuels and biofuels are shipped, and which Annex ofMARPOL they fall under. MARPOL Annex I covers theprevention of pollution by oil and MARPOL Annex IIcovers the control of pollution by noxious liquidsubstances carried in bulk. Blends of biofuels and

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conventional fuels are essentially mixtures of mineral oilbased hydrocarbons and noxious liquid substances. Atpresent, the International Maritime Organization (IMO)Bulk Liquids and Gases sub-committee are addressingthe issue of how to classify the blends. In the interim,provisional measures are in place which state thatblends of conventional fossil fuels and biofuels in whichthe proportion of biofuel component is less than 15%should be carried under the provisions of MARPOLAnnex I. Blends with a proportion of biofuel componentgreater than 15% would have required the shipper inquestion to contact an administrator for a decision onhow the product should be carried. These measureswere to remain in place until July 2009 but have recentlybeen extended until July 2011 and have beendeveloped to take the form of a 3-band system asfollows:

Band 1: 85% or more petroleum oil (15% or lessFAME) – Product is carried as an Annex I cargo. Oildischarge monitoring equipment (ODME) should beapproved/certified for the mixture carried or tankresidues and all tank washings should be pumpedashore.

Band 2: More than 1% but less than 85% petroleumoil (15% to 99% FAME) – Product carried as an AnnexII cargo. Blend is treated as tripartite mixture in line withMEPC.1/Circ.512 but ship type cannot be lowerspecification than any component in the blend;orCargo treated as pollution category X, ship type 2 withworst case minimum carriage requirements assigned(based on analogous products in the IBC Code such aspyrolysis gasoline, butyl benzene or the generic entryfor n.o.s. (4) products)

Band 3: 1% or less petroleum oil (Greater than 99%FAME) – Product carried as Annex II cargo and cargotreated as the Annex II product contained in the blend.Issues of concern include the potential effect thatFAME and ethanol cargoes might have on ODMEequipment – it is understood that further testing isneeded to clarify this issue. The varying blend levelsalso impact upon how the cargo is measured – work iscurrently being undertaken on samples of FAME fromvarious origins and at different blend levels to establishsuitable volume correction factors (VCFs) to be used incargo measurement.

Future developmentsUp to this point, discussion has been limited to FAMEand bioethanol, the so called ‘first-generation’ biofuels.The Renewable Energy Directive was updated inDecember 2008 to include sustainability criteria for

biofuels, amid worries that the biofuels currently inproduction were not being produced in a sustainablemanner. In order to meet the various legislative targets,not only will the volumes of biofuels used need toincrease, but technology will need to be developed andmade commercially viable to bring new, sustainablebiofuels onto the market. Examples of such biofuelsinclude; biodiesel produced from algal oil, biodieselproduced from the crop jatropha (which does notcompete with food crops for land), bio-butanol (which isa slightly longer chain alcohol than ethanol) producedfrom renewable sources of biomass, and ‘renewablediesel’, a synthetic diesel which would meet the EN590diesel standard, produced by the catalytic hydrogenationof vegetable oils.

ConclusionsIt is clear that the integration of biofuels and blends ofbiofuels with conventional fuels into our current fuelinfrastructure has raised a number of issues, many ofwhich were unforeseen and have only come to light afterthe introduction of the fuels. The majority of the problemsconcern FAME, both as a neat product and as a blendwith petroleum diesel. The variety in the feedstock whichcan be used to produce FAME can impart very differentproperties on the FAME produced. In Europe there iscurrently only a single FAME standard, and the particulartype of FAME, and therefore the properties the materialmay be expected to display, may not always be clear fromthe shipping documents.

The major issues for consideration for those involved inshipping FAME are the high potential for watercontamination and associated problems withmicrobiological spoilage, and, whilst a 5 ppm limitremains in the DEFSTAN 91-91 jet fuel specification, thepotential for contamination of jet fuel cargos by traces ofFAME. Additionally, the relative instability and sensitivityof the material to low temperatures and trace metalsrequire extra care in terms of how the product is handled.Bioethanol and gasoline blends are also sensitive towater contamination with the potential for irreversiblephase separation to occur if the level of water passes acertain threshold level.

Of course, it is possible that as blend levels increase,new and unforeseen problems will arise that will requirefurther research and new approaches to our way ofdealing with these materials. It is likely that biofuels willcontinue to provide a very real challenge to all thoseinvolved in their production and distribution over thecoming years, and a knowledge of the often quite uniqueproperties that these products display will be verybeneficial for those wanting to minimise the risk of facingunwanted claims.

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Liquid natural oils, fatsand fatty productsThe products dealt with below include crude vegetable,animal and marine oils as well as fats. Some of the oilsare edible and others are used in the production ofsoap, paint, lacquer, cosmetics and medicines.Occasionally, refined vegetable oils are shipped. Whenthese products are transported by sea, a variety ofdifficulties may be encountered, the cause of whichgenerally fall into two categories.

● Handling (basically temperature control)

● Contamination.

HandlingClaims still frequently arise which involve allegations ofunsatisfactory handling by ships. It is sometimesnecessary to apply heat to these cargoes, since duringa sea passage, the temperatures encountered are likelyto be lower than those recommended by the shippers.Many products of this type are adversely affected byheating so that some deterioration is inevitable, with theextent of the damage depending on the nature of theproduct and length of the voyage. Unsatisfactorytemperature control can cause additional deterioration,usually because the carrying temperature has been toohigh for all, or part of the voyage. It is possible forexperts to estimate the level of unavoidable damageand hence the extent of any further damage caused bypoor temperature control.

Damage may also result if the carrying temperature isallowed to fall below that recommended by theshippers. The normal procedure for heating this type ofproduct is by heating coils at the tank bottoms andlower sides, with heat being transferred throughout theoil, mainly by convection current. The heat transferbecomes progressively less efficient as viscosityincreases. The viscosity of liquid natural fatty productsis greatly affected by temperature and a reduction intemperature of only a few degrees can have a seriouseffect. If the heating process is inadequate to themaintenance of sufficient fluidity within the bulk ofcargo, then the liquid in the vicinity of the heating coilscan become overheated.

During the discharge of cargo, if the environmentaltemperatures are very low, further problems may ariseas a result of solidification, which most commonlyoccurs when a tank is almost empty and the liquid levelhas fallen below the level of the heating coils. Undersuch circumstances, the final residues may be removedby sweeping or by steam stripping, provided the

receivers are able to accept the fat and water mixturewhich is produced. Ship’s officers responsible fordischarging heated products in cold climates shouldensure that the maximum pumping rate is maintainedand that there are no interruptions during discharge,shore operations permitting.

ContaminationIn the past, the most common contaminant, resulting inclaims, was water, originating from shore or ship tanks,pumps or lines at the time of loading, or introduced bymistake, or due to leakage. Some products contain asignificant quantity of water when shipped, but thepresence of excess water in others may acceleratedeterioration. Experts can frequently estimate thedamage due to contamination with excess water.

More recently, traders and governmental authoritieshave taken a serious view of the contamination of edibleproducts by traces of chemical substances. Often, butnot invariably, these contaminants have come fromresidues of previous cargoes.

It is normal practice for samples to be drawn byindependent surveyors during loading, or immediatelyafter loading, and for at least one set of these samplesto be given to the ship. It is important that the ship has aset of loading samples, since most claims are basedupon differences in analytical parameters in samplesdrawn at loading and discharge. If the master isinstructed to deliver a set of samples to the receivers onarrival at the discharge port, it is recommended that herequests that the shippers provide a second set ofsamples for the use of the shipowners. Any suchsamples handed to the ship should be properly storedduring the voyage, preferably in a refrigerated store.

At the time of discharge, samples are always drawn bythe receivers or their surveyors. Normal analysesconducted at both load ports and discharge ports arequite straightforward and the typical parametersdetermined are water, free fatty acid, unsaponifiablematter and odour. If there is evidence or suspicion thaton delivery the cargo does not conform to either aspecification or to the loading samples, more detailedchemical analysis may be performed. There are nowreliable and effective procedures available fordetermining traces of chemical contaminants. Certaincontaminants can be identified and determined atlevels as low as 10 parts per billion (ppb).Contamination at this level will result from admixture of10 grams of contaminant, with 1000 tonnes of cargo.Most chemical contaminant can be identified anddetermined at levels of 100 ppb or 100 grams per 1000tonnes of cargo.

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When cargo is loaded or trans-shipped, it is essential toconsider the nature of previous cargoes. In somecases, it is virtually impossible during tank cleaning toremove all traces of previous cargo to a level which isnot detectable by modern laboratory equipment. Forthis reason, restrictions are laid down in the contractsof sale, regarding the immediate previous cargo carriedin each of the ship’s tanks. These restrictions areimposed within the industry by such bodies as FOSFAand NIOP. Their rules should always be consulted.They are constantly under review and may change inthe future. Similar restrictions were imposed in the pastconcerning leaded petroleum or other leaded products.Shippers and charterers should be notified in good timeof the nature of the three previous cargoes carried ineach individual tank.

It is important that, before loading, every care andattention should be paid to the proper preparation oftanks, pumps and pipelines. It is very important that thetank coating is maintained to a high standard. Thecoating covering all sections of the tank must be sound.Where any breakdown of the coating takes place,particularly where epoxy and polyurethane coatings areconcerned, there is a risk that the remains of previouscargoes may accumulate, creating a potential source ofcontamination. The breakdown of epoxy coating usuallymanifests itself in the form of blisters, open or closed, orin areas where the coating is detached, formingpockets which cannot be reached by cleaning water. Inthese areas, there is also a risk that rust may form,which is again likely to trap cargo residues and lead tocontamination. It is not possible to properly clean tankswith damaged coatings. Cases have been recordedwhere traces of the third previous cargo have beenfound when samples of damaged coatings were tested.

Another possible source of contamination is thepenetration and softening of epoxy and polyurethanecoating by a previous cargo. This may find its way laterinto newly loaded products. Masters should always

consult the ‘cargo resistance’ list provided by themanufacturers of the tank coating. This will list thosecargoes to which the tank coating is resistant. Forcargoes not included in the list, or cargoes withoutresistance indicators, or when deviating from themaximum temperatures indicated on the list, themanufacturers should always be consulted.

Bearing in mind that even the most minute traces ofprevious cargoes may be discovered, (although thismay not always lead to significant damage), it is evidentthat the washing of cargo tanks must be performed withthe utmost care. The precise method of cleaning willdepend on the previous cargo carried and the state ofcleanliness required for the products to be loaded. Therelevant tank cleaning guides should always beconsulted. Generally, the most important part of thetank cleaning process is butterworthing with hot or coldsea water at sufficient pressure and at the appropriatetank levels. This should be followed by fresh waterwashing in order to remove sea water residues. Tankswhich may have contained monomer or drying oilsshould first be washed with sufficient quantities of coldwater to avoid polymerisation of cargo residues. Insome cases it is necessary to employ tank cleaningchemicals but their use is generally limited as it may bedifficult to dispose of slops.

On completion, the tanks should be clean, dry and freefrom residual odours. It may also be desirable to takewallwash samples and have them analysed for traces ofprevious cargoes, but this requires skilled inspectors.The presence of an odour in a tank, which has beencleaned, indicates the presence of cargo residues andalso indicates the need for further cleaning. It isadvisable, when checking for residual odours, to makethe test after the tank has been closed for a period.

Interior of tanksBelow left: A newly coated tank.Below right: Coating starting to break down but clean.

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Testing should, in any case, be carried out by personnelwho have not been working in or near the tanks for atleast one hour.

When cargo with a high melting point has been carried,tanks should be washed with hot water. If possible,steam should be used to ensure the residues areeffectively melted and cleared, and the cleaningprocess must also include the tank lines, tank lids andvent lines, including pressure vacuum valves and risers.Examples of cargoes with high melting points includephenol and waxes.

Cargo pumps, usually of the hydraulic deep well type,should be dismantled and inspected, as recommendedby the manufacturer. The pumps should be purged inorder to test the seals which separate the cargo and thehydraulic oil from the void space in the pump. Thisprocedure should always be followed after tankcleaning, before loading and discharging and afterrepairs. The results should always be properlyrecorded in the ship’s log book or other formal records.Where defects to the seals are suspected, cargoshould not be handled until corrective measures havebeen taken. Due consideration must be paid to the trimof the ship when cleaning pumps, in order to ensurethat any contamination product is properly drainedaway. Portable pumps should be tested before beinglowered into the cargo tank.

Before loading, if heating coils are not to be used, theyshould be thoroughly purged and blanked both at thesupply and the return ends. Even though coils may havebeen in use for some time, they should be pressuretested before loading, in order to avoid the possibility ofcontamination through leaks which might havedeveloped. Pumps not required for cargo handlingshould always be isolated.

Special attention should be paid to the cleanliness ofvent lines, as they may contain residues of previouscargoes, both in a liquid and a solidified state. Ventlines, when not cleaned after discharge, may drain intoa newly loaded tank when the vessel changes trim orwhen encountering heavy weather. Solidified cargoresidues in a vent line may melt, due to the heat emittedfrom a heated cargo and the melted product may drainback into the tank, causing contamination. The practiceof steaming ventlines after the carriage of heatedcargoes is to be recommended as blocked lines mayresult in over-pressuring of cargo tanks.

Drain cocks which are fitted at the lowest parts of deckand manifold lines, as well as plugs at the bottom ofcargo valves, should be opened and rinsed in order toremove any trapped cargo residues. These drain cocks

may contain sufficient liquid to result in seriouscontamination. When clearing deck and drop lines it isimportant to ensure that the dead ends of these linesand drop lines are not overlooked. They should beopened and thoroughly cleaned.

Mild steel tanks are still sometimes used for thecarriage of natural oils and fats but their use is in declineas cargo charterers more frequently stipulate the use ofstainless steel or coated tanks. When used, mild steeltanks should be free from rust and scale, sinceremnants of previous cargoes are likely to be trappedand transferred into subsequently loaded cargoes.Where sensitive cargoes have been carried in mildsteel tanks, contamination has been known to occurfrom the residues of hydrocarbon (petroleum products)cargoes.

The importance of proper tank cleaning proceduresand the correct preparation of tanks and all relatedequipment prior to loading cannot be over-emphasized.Masters may wish to consider appointing anindependent surveyor to verify the condition of the tankcoating, heating coils and hatch openings after the tankpreparations are completed.

On completion of loading, an ullage survey by anindependent surveyor may be appropriate, whereaftervalves and hatches should be sealed. This process canbe repeated at the discharge port. The practice oftaking onboard samples at all stages of the loading anddischarging operation which is referred to earlier, isalso to be highly recommended.

Should contamination occur at some stage in thecourse of transit, it may be possible, by analysis of suchsamples, to identify the source of contamination. Byensuring that the cargo is carried to the higheststandards, the product should be well protected.

Tanker Matters is a compilation of Carefully to Carry articles.Bulk oil cargoes, Samples and sampling and Liquid natural oils werefirst produced for the Carefully to Carry manual and were revised inSeptember 2006. Biofuels was produced in July 2010 and written byRichard Minton of Minton Treharne & Davies. All articles are availableon the UK Club website ukpandi.com

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Tanker Matters videoTanker cargo claims - how they are caused, andhow to avoid them

The UK Club’s Cargo Matters series of videos aims toincrease awareness of the causes of P&I claims forcargo damage and loss. Tanker Matters focuses onsome of the most frequent causes of tanker cargoclaims and how to avoid them.

The DVD can be viewed continuously, or scene byscene:

● Introduction

● Ensuring the ship is suitable for the cargo

● The cargo plan

● Preparing cargo systems

● Before loading - the key meeting and lining up

● Loading

● The loaded voyage

● Discharging

● Summary

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UK P&I CLUBIS MANAGEDBY THOMASMILLER

For further information please contact:Loss Prevention Department, Thomas Miller P&I LtdTel: +44 20 7204 2307. Fax +44 20 7283 6517Email: lossprevention.ukclub@thomasmiller.com