Bubbles?20th January 2012 05:05 GMT

2011 saw a sharp rise in claims of entrained air in bunkers. Entrained air, or the 'cappuccino effect' as it is morecommonly known, is an increasingly cited phenomenon by fuel buyers that occurs during bunkering. However,there appears to be a lack of understanding regarding what constitutes entrained air in bunkers. The confusion inthe industry today seems to stem from whether the presence of air bubbles seen in fuel upon delivery is normalor excessive.

Entrained air may occur for example due to the practice of tank stripping, which is the process of pumping fromthe bottom of a bunker tank in order to empty it which can produce entrapped bubbles in fuel. Consequently iftank stripping is not controlled effectively this can make a fuel delivery appear to be of a larger volume (and thederived fuel mass) than it actually is.

Air-blowing (also known as purging) after bunkering is also a standard industry practice to aid in cleaning of thebunker delivery hose before being detached from the receiving ship to help avoid any oil spill. Although thispractice is common, there have been cases where this process has been abused. Therefore it is of utmostimportance to distinguish between genuine instances of aerated bunkers, and occurrences where there is intentto abuse existing standard industry bunkering procedures.

The potential economic losses when entrained air is deliberately introduced into fuel can be substantial and it isunderstandable that ship owners might be concerned about cappuccino bunkers especially in today's climate ofhigh fuel costs and depressed earnings capacity by ship operators. However, it is important for fuel buyers tounderstand that tank stripping and air blowing at the end of the bunker delivery are common industry practices,as far as they are effectively controlled and not done excessively.

Bunker surveyors will measure the quantity of fuel of the nominated bunker tanks of the barge prior to delivery atwhich point entrained air if encountered and observed would be reported. Together with the closing sounding ofthe bunker delivery barge an industry acceptable accurate quantity figure can be derived, which would constitutethe delivered bunker quantity. Fuel surface air bubbles may be observed by the receiving ship after bunkerdelivery, however, these should be considered superficial in nature after taking into account tank stripping andhose clearing. Frequent gauging of the receiving tanks during bunkering is one of the methods that can give aclear sign of any air being introduced as accumulated air bubbles can be seen on the gauging tape.

Notwithstanding the presence of an independent surveyor during bunkering the following warning signs wouldindicate something is amiss with a bunker delivery to the crew onboard the receiving ship. - Bunker delivery hose jerking.- Gurgling sound when standing in vicinity of bunker manifold.- Fluctuation of pressure indication on the manifold pressure gauge.- Fluctuations of level indication gauge of bunker tanks.- Excessive bubbles observed on the sounding tape prior and after delivery.- Slow delivery rates, when air is being introduced during pumping.

If several of the above warning signs are observed, the ship's crew should, preferably with the help of anindependent surveyor, launch a thorough investigation to get to the root cause of any potential malpractice ofentrained air during bunkering operations.

It is worth reiterating that it is fairly common for the bunker delivery hose to jerk and for superficial air bubbles tobe observed following hose clearing and these should not be deemed automatic indicators of foul play. If theopening gauge is performed correctly, the quantity would have been measured prior to the hose clearing and/ortank stripping. Hence, any froth observed after would not have any bearing on the quantity delivered as such.

Working with surveyors to measure bunker quantity is one of the key measures of preventing misunderstanding.It is also important that any concerns are flagged as soon as they are noticed and shortly after delivery. It goeswithout saying that surveyors are independent parties whose first priority is to ensure the accuratemeasurement of fuel quantity.

Douglas Raitt, 20th January 2012 05:05 GMT

Comments on this Article

Steve Findlay25th January 2012Interesting article and particularly given that I am involved in the investigation of a number of "cappuccino effect"issues at the moment. Most of the bunker delivery shortfalls tend to be around 20mt to 50mt but I have oneparticular case that involves a shortage of 250mt and this represents around 30% of the total product alleged tohave been supplied. There are rumours that Nitrogen is somehow introduced into the fuel at or prior to deliveryand I would be interested to know if there have been any similar reports.Douglas Raitt

Bunkerworld Forums - BunkerBlogs - Bubbles? http://www.bunkerworld.com/forum/blogs/24/109980/Douglas-Raitt/B...

1 of 2 6/16/2012 8:48 AM

Lloyd's Register FOBAS31st January 2012Hi Steve, to our knowledge there have not been similar reports. It is hard to see why anyone would resort tosuch a tactic as Nitrogen is a high premium product and there would appear to be little benefit in using nitrogenas opposed to (free) air in such situations. Air, in any case, consists of 79% nitrogen after all. If this in an actualscam it would have to be quite sophisticated in order to have the required nitrogen on hand. However, it'sdifficult to fathom a good reason why anyone would go through all that trouble. It may be the case if the nitrogentakes much longer to migrate out of the oil (till the receiver is well over the horizon), but even so, any sampledrawn out of the bunkers would still have the appearance of an aero chocolate bar.

Of course, since any Residual Fuel Oil can be 0.2% - 0.8% (even over 1%) elemental nitrogen, anything up tothose limits should not be taken as a sign that nitrogen has been deliberately introduced into the fuel.Steve Findlay18th March 2012Many thanks for your reply/comments Douglas and yes, I would agree that using Nitrogen seems to be a ratherpointless and indeed difficult means of inflating the product. We are presently carrying out tests using variousgases and chemicals as we now have a very similar case involving a shortage of 330mt on a delivery of1750mt. This is clearly becoming a somewhat serious issue that may well lead to significant consequencesinvolving bunkering operations at Singapore.Jerry WangEmerson Process Management Asia-Pacific Pte Ltd30th March 2012Emerson mass bunker flow meter can take care of aeration issue in bunkering.Oleg MicevicCross Keys Maritime Solutions Pte Ltd11th April 2012Dear Steve and Jerry,

I dont think it is necessary to have a mass flow meter to detect a loss of 20% of delivered bunker fuel.Also, with losses on that scale it would be probably wiser to investigate the individuals involved in thistransaction on all sides and report it to the relevant authorities.Robert MarkojaCiDRA Power Generation12th April 2012This is a very interesting blod. I have had 2 inquiries within 3 days regarding air entrainment in bunker fuels.Both inquiries were from companies interested in determining the amount of air in the bunker fuel that becameapparent to them after a couple of days following natural de-aeration or settling of the oil. The CiDRASONARtrac GVF-100 Gas Volume Fraction meter can be used to assess the amount of entrained air in bunkeroil during transfer to ship. The GVF-100 clamps on the outside of a pipe and is able to provide real timeentrained air measurements in the range of 0-20% air / gas by volume. This equipment has been used to correctpositive displacement flow meters used for crude custody transfer and with coriolis meters used on 2-phaseseparators for oil field applications.Shishir DuttTolani Maritime Institute14th April 2012Dear Robert ,Can you please comment on the initial cost , working principle , size and operation of this GVF-100 gas volumefraction meter . Which company has designed the same and it will be great if you can cite some examples whereit has actually been on continuous use during each bunkering operationSteve Findlay17th April 2012Hi Robert and Jerry. Whilst I am sure the equipment may help in reducing losses due to air or gas inflation of fueldelivered to a vessel, the crux of the issue is that it is something which is clearly happening, mainly at SingaporeI believe, and absolutely nothing is being done about it. I have six shortage cases on my desk at the momentand doubtless there are many more out there. What is needed is a forum whereby shipowners andshipcharterers who purchase fuel and then encounter such shortfalls, can identify the suppliers, supplyingbarges and surveyors involved. Of the six cases on my desk, two involve the same bunker barge and it may bethat there are many other similar cases out there with that particular barge.

If anyone has any similar cases or experiences please email me at steve@findlaymarine.com

2012 Petromedia Ltd Terms of Use Contact Us

Bunkerworld Forums - BunkerBlogs - Bubbles? http://www.bunkerworld.com/forum/blogs/24/109980/Douglas-Raitt/B...

2 of 2 6/16/2012 8:48 AM

Do not be caught off guard by introduction of new sulphur limit2nd November 2011 06:32 GMT

By now it is common knowledge that in less than two months, on the 1st of January 2012, the global sulphur capwill fall from 4.50% to 3.50% in accordance with MARPOL Annex VI regulations. It is important for ship operatorsto note that in order to comply with the new regulations, action needs to be taken now.

In order to prevent being caught off guard, it would be wise for shipowners and operators to begin the transitionas soon as possible. As this limit applies to the fuel oil as it is actually used, it will be necessary to ensure thatany fuel oil on board with sulphur content that exceeds 3.50% m/m has been fully consumed.

Most importantly, the maximum sulphur limit given in charter party bunker clauses or bunker nominations willneed to be duly amended sufficiently in advance of the deadline in order to avoid ships being supplied withquantities of fuel oil about the 3.50% m/m limit which they will not be able to consume fully before theimplementation date.

Since the 3.50% limit is not restricted to those delivering sulphur controlled fuel oil to be used in EmissionControl Areas, all suppliers need to be mindful that they are prepared to supply fuel that is compliant with the newlimits.

Even as suppliers work to ensure adequate supply of fuel that meets requirements, according to FOBAS data,10-15% of bunkerings worldwide will be affected by this change. Due to the international nature of the petroleumindustry, affected fuel will not be isolated to oil producing areas that are known for their high sulphur fuels.

It is worth noting that in accordance with MARPOL Annex VI requirements, it is the responsibility of receivers offuel oils to ensure that all bunker delivery notes provided by suppliers correctly document the actual sulphurcontent and that the value does not exceed the maximum specified.

Leaving these necessary steps to the last minute could have costly consequences for ship operators who findthat there is excess fuel in their tanks that does not meet requirements and needs to be blended or, in aworst-case scenario, de-bunkered. This is not to mention the potential penalties should they find themselves onthe wrong side of regulations come the New Year.

Douglas Raitt, 2nd November 2011 06:32 GMT

2012 Petromedia Ltd Terms of Use Contact Us

Bunkerworld Forums - BunkerBlogs - Do not be caught off guard by int... http://www.bunkerworld.com/forum/blogs/24/107814/Douglas-Raitt/D...

1 of 1 6/16/2012 8:49 AM

Testing means17th December 2010 03:44 GMT

2010 has been an interesting year with a number of important regulations introduced and great strides havebeen made in improving fuel standards. The introduction of the revised ISO 8217 standard in particular drew aloud debate with numerous industry players voicing their concerns. However, it is worthwhile to carefullyexamine whether the hue and cry over the cited limitations of these standards have a real basis in fact.

Most recently, the issue of H2S has been raised again with some testing agencies declaring that the 2.00 mg/kglimit was insufficient to protect from the dangers of H2S. In November, FOBAS issued a bulletin addressingsome of these concerns. While theory is undoubtedly important in establishing guidelines, the conclusion shouldbe grounded in a fair amount of reality and based on facts before declaring danger.

A technological possibility of complete removal of H2S from bunkers does exist, but it would need to beassessed against the price of such fuel treatment before implementation of such a step on a large industrialscale. After all, the use of residual fuel for so many years as marine fuel has been almost solely based oncheaper price market drivers.

The established H2S limit is a preventive measure as there have not been widespread reports of shipownersfacing problems with H2S, nor is it a new issue and most are aware of the potential problems as well as themeasures to guard against it as part of overall occupational safety hazard measures.

While speculation also ran rife regarding the projected increase in off-specification fuels with the introduction ofthe new standard, the reality was that the vast majority of fuels fell within the new specification limits regardlesswhether they were using the ISO 8217:2005 or ISO8217:2010 standard. In fact, the new limits bore in mind thequalities of fuel already being available in the market, the tightening limits left less leeway for variation but mostfuels supplied today already meet ISO 8217:2010 standards.

The situation in laboratories can be far removed from the realities on ships themselves. While safety is ofcourse a key concern, we have found that issuing baseless warnings against contaminants that may be totallyharmless and are not based on real dangers can cause more harm than good and lead to a significant amount ofdisinformation being disseminated and confusion created throughout the industry.

The danger of raising suspicions before they are substantiated by both further study and empirical evidence ofdamage on ships is to confound the industry and will lead to increased costs in terms of time and money. Fueltesters are often regarded as experts, as we should be, however, it is therefore extra important that we weighwhat we say in acknowledgment that there are implications when we sound warnings.

As fuel testing agencies, we have a responsibility to work in the best interests of our customers. This does notonly mean ensuring that they receive fuel that is tested to be safe for use and fit for purpose, but also that theyare not burdened by unnecessary costs. It is increasingly beginning to seem that the key interest of testingagencies is to drum up more sample numbers rather than doing a technically sound job as a fuel testing serviceprovider. Ship owners rely on us to provide sound technical advice and potential problems are not necessarilyactual problems - crying wolf is in no one's interest.

Douglas Raitt, 17th December 2010 03:44 GMT

2012 Petromedia Ltd Terms of Use Contact Us

Bunkerworld Forums - BunkerBlogs - Testing means http://www.bunkerworld.com/forum/blogs/24/98982/Douglas-Raitt/Tes...

1 of 1 6/16/2012 8:55 AM

The Black Art of Blending28th May 2012 04:26 GMT

As rising costs cast the spotlight on bunker fuel, blending practices have become more advanced and complex.Indeed, the process of blending plays a critical role in helping ship operators to receive fuel that is not only fit forpurpose and safe to use, but also offers the best price per metric tonne of fuel in terms of energy content.Recently, a variety of factors have influenced the blending process and this has had an impact on thecomposition of fuel delivered to ships.

The product in bunker tanks on board of ships is the result of optimization between production costs andcompliance with customer specifications. The main target blend specification for bunker fuel in the past wasinitially viscosity, reflected in product names such as IFO180, IFO 380 etc. As refining techniques became moreand more sophisticated density also became a critical blend target. This often required blending heavy grades ofresidual product with more costly distillates and cutter stocks to enable the fuel to be used safely. In this sense,blending was primarily a means of producing fuel that was both economical (using the least amount of cutterstock to meet specification targets) and fit for purpose.

With the development of marine fuel standards such as ISO 8217, fuel blends also need to meet certain criteriathat set out the parameters and general guidelines as to what constitutes acceptable fuel quality. At its core,blending needs to account for key qualities of fuel to be considered fit for purpose, stable with good ignitionquality and combustibility. It is vital that all cutter-stocks used are compatible with the nature of the residual basestock in order to ensure the stability required of the overall blend is achieved.

In recent years, changing environmental regulations have played a big part in shifting blending priorities and thishas had consequences throughout the supply chain. Where blending was previously meant to help shipoperators balance costs with functionality, growing sulphur regulations have meant that the sulphur content ofthe fuel has become a critical parameter in the blending process.

Low sulphur fuels may have different qualities from high sulphur fuels and may create problems for some enginesif the ignition properties of blended fuel are impacted due to an unusual density/viscosity relationship as definedby the CCAI in ISO 8217: 2010. Blending to produce low sulphur fuel can also result in fuels with poor stabilitycharacteristics and possibly higher cat fine content if slurry oils are used as cutter stock. This makes itespecially important for suppliers and ship operators to test fuel that has been blended to meet sulphurrequirements and to also ensure that the fuel meets international marine fuel oil standards.

Other trends such as bio-derived components becoming increasingly more popular in land based fuelapplications over the years due to for example lower SOx and PM emissions, the likelihood that it could becomepresent in the marine fuel supply chain may also increase. Fatty acid methyl ester,or FAME may pose adverseconsequences when used in ship engines, the full effects of which are still being studied. ISO 8217:2010 doesnot allow the use of FAME, however it is difficult to avoid completely due to FAME being surface active, stickingto metal or glass surfaces. The risk of cross contamination where supply chain terminals, barges and truckshandle both marine fuel and bio-diesel are therefore real.

While it is important for ship operators to meet their fuel requirements while minimizing costs, it is vital that theblending processes in the marine fuel supply chain not be overlooked. The costs of improper blending are veryreal and can result in off-spec fuel which in turn may be difficult for onboard handling and/or damage ships'engines. Fuel quality is constantly changing to meet the shifting demands of regulatory and economic forces andthe supply chain needs to evolve with these effectively.

Douglas Raitt, 28th May 2012 04:26 GMT

Comments on this Article

Enel ReinaACP30th May 2012great article, we recently had been hit by a fuel with alkylphenols and Alcohols.

2012 Petromedia Ltd Terms of Use Contact Us

Bunkerworld Forums - BunkerBlogs - The Black Art of Blending http://www.bunkerworld.com//forum/blogs/24/113456/Douglas-Raitt/T...

1 of 1 6/16/2012 8:47 AM

Bunkerworld Forums - BunkerBlogs - Bubbles_Bunkerworld Forums - BunkerBlogs - Do not be caught off guard by introduction of new sulphur limitBunkerworld Forums - BunkerBlogs - Testing meansBunkerworld Forums - BunkerBlogs - The Black Art of Blending