GreenDelayedPetcoke_000

PROJECT Precautions when fixed

for Green Delayed Petcoke

© Copyright Strømme AS 2004-

Nesveien 15, PO Box 31 N-1305 Haslum, Norway Ph +47 67 52 60 60 Fax +47 67 52 60 50

Part of Stromme ASA

Table of contents

1. PREFACE........................................................................................................................ 3

2. BACKGROUND.............................................................................................................. 4

3. FROM “BLACK TO WHITE”...................................................................................... 4

4. OBSERVATIONS ........................................................................................................... 7

5. WHAT IS GREEN DELAYED PETCOKE? ............................................................... 8

6. LAB ANALYSIS & TESTS.......................................................................................... 11

6.1. COMMENTS ............................................................................................................ 16

7. SOLUTIONS TO THE PROBLEMS.......................................................................... 16

8. CHEMICALS ................................................................................................................ 17

8.1. CLEANING CHEMICALS.......................................................................................... 17 8.2. PREWASH / BARRIER CHEMICALS ......................................................................... 19

9. EQUIPMENT ................................................................................................................ 19

10. CONCLUSION: ............................................................................................................ 20

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1. Preface Gentlemen! This document would not have been possible to make unless for a close cooperation and exchange of information and opinions with some of you senior guys in our industry. To all of you, I much appreciate your support and hope that we can all benefit from this small project, not at least our seamen, who have been supporting me in a very good way and are carrying the heavy burden. A special thanks to those of you, who have trusted me with confidential reports and photos! Also to representatives from coke plants and paint manufacturers, who will not have any direct benefits from this project at all, my thanks for your time and support. As you will understand, this is another status report only. However, for quite some while you have contributed to this small project, and I find it is due time to send you a second report. Since last time, full scale tests have been carried out onboard quite a number of bulk carriers, which has brought our small study a step forward. In my opinion, at Stromme we have now got a certain understanding of what it is all about. At least, now we know that there are different grades of petcoke (Petroleum coke), and we know the difference between coal and products being produced of the sludge from crude oil refinery. We even believe we know why the transport of Green Delayed Petcoke creates different cleaning problems to those after discharge of Calcined Petcoke and Coal, and that we have a possible “Solution to the Problems”. Hopefully, our ongoing lab analysis, our small and full scale tests can soon be concluded. At Stromme we work hard to Save you time and to stay in the forefront. Hopefully, this small project will contribute to our efforts. To the best of our knowledge, the information in this report is correct. However, since the circumstances and conditions to which the cleaning advice, product usage and handling are beyond our control, we do not accept any loss or damage that may occur. My personal thanks to all of you! I will keep you closely informed of any progress. With kind regards, Strømme AS _______________ Jahn Stryken (sign.) Haslum, July 28th 2004

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2. Background During recent months, several vessels have got hold cleaning problems after discharge of Green Delayed Petcoke and similar cargoes. This has resulted in many days of off hire and/or costly cleaning including repainting of the cargo holds. Generally, the problem has been that onboard cleaning equipment, chemicals and procedures have solved the problem 90-95 % only, and a thin film (footprint) from the cargo has been very difficult to remove. Present solution to the problem: one more cleaning and chemicals heavily activated by brushing and/or high pressure cleaning of 350 to 700 bars (which requires close up access), and in the worst case repainting, all depending on the cleanliness required for the next cargo. The cleaning after cargoes such as Coke, Coal and Calcined Petcoke has not been so much of a problem. However, Pitch Coke seems to have similar characteristics to Green Delayed Petcoke. Ref.: photos below. 3. From “black to white” After discharge of coal (next cargo=grain): Problem solved from tank top level: Note: The photos are taken onboard a gearless Panamax bulk carrier. The vessel was equipped with powerful equipment for cleaning from tank top level, and the operator followed up closely. The vessel passed inspection for grain. When tested by hand for grain inspection, stains from the old cargo did not come off. Note: Sometimes you get a bond between cargo residues and surface at electrolytic level. A possible problem can best be checked by whipping with a cloth, or simply by using your hand, which is common practice also by cargo surveyors when inspecting the holds for the next cargo.

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Coke (Next cargo = Soya for Australia): After cleaning from tank top level:

Note: The photos are taken onboard a geared Handymax bulkcarrier. The operator visited the vessel during the cleaning operation. The vessel passed inspection for Soya, which is not the easiest task. The black shadows are from a previous cargo, and were impossible to remove, even by strong alkaline chemicals activated by heavy brushing. A few weeks later, the same chemical had a small dissolving effect only after discharge of Green Delayed Petcoke from a similar vessel. During discharge of Calcined Petcoke: After cleaning to “Pulp standard”:

Note: The photos are taken onboard a 42.000 Dwt bulk carrier of Open Hatch design. These vessels require a cleaning standard much higher than grain (standard of cleanliness to be “Hospital Clean”). The cleaning was performed from tank top level. Total time for preparing 2 cargo holds for the next cargo = 28 man hours, all included. The vertical stains are from a previous cargo of black rubber, and will not come off or create any problems in this trade.

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Inspection after discharge of Pitch Coke High pressure cleaning from crane (Pencil Pitch): basket:

Note: The photos are taken onboard bulk carrier of Open Hatch design. The crew has tried various chemicals and high pressure cleaning, however with no success. The characteristics of this cargo, and the cleaning problems involved, seem to be similar to Green Delayed Petcoke. Before loading of Green Delayed After discharge (stains all over): Petcoke: Note: The photos are taken onboard a 44.000 Dwt bulk carrier of Open Hatch design. Next cargo = Potash, which requires a high standard of cleanliness. We can all agree, that if stains/ footprints of previous cargos are allowed to accumulate over time, this may result in a costly cleaning and renewal of cargo hold paint! Time for cleaning and applying of cosmetic paint: 11 days.

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After discharge of Salt (last cargo = Coal): After discharge (next cargo = Grain):

Level of cargo

The corrusion have had different activityProbably dependant on amount of coal strainsleft prior to salt loading

Note: The photos are taken onboard a Panamax bulk carrier after discharge of salt. Before loading, the hold paint was in a good condition, and lime washing not considered to be necessary. When visiting the vessel, the operator found different activity of corrosion and still some coal stains from the previous cargo. Coal contains sulphur and carbon (and raw Petcoke even more), and it is believed that a chemical reaction with the salt started the fast attacking rust process. The vessel passed inspection for grain after being cleaned from tank top level. 4. Observations Cleaning and maintenance of cargo holds are two sides of the same coin. As a thumb of rule, even though it is not considered necessary to clean the cargo holds for the next cargo, residues and stains from previous cargos should not be allowed to accumulate. Cargo holds need to be cleaned and maintained to meet the future requirements in existing and possible new charters. These costs will easily be saved in reduced cleaning, maintenance and off-hire in the future. Green Delayed Petcoke (+ Pencil Pitch = Coal Tar Pitch and Pitch coke) gives a different cleaning problem to solve compared with cargoes such as coal and calcined petcoke. When cleaning after coal, the main problem is to dissolve “oil stains” from the cargo, which can be overcome by use of high alkaline chemicals applied as wet foam and powerful air/water cleaning from tank top level, or by use of high pressure cleaners from crane baskets. Green Delayed Petcoke (+ Pencil Pitch and Pitch coke) seems to leave a thin layer of colour pigments, probably from asphaltenes contained in the pitch (unconverted vacuum residuum – crude oil heavy fractions in raw petroleum coke), which needs to be dissolved by chemicals. This gives a different cleaning problem to that from “oils stains” of coal. We are working to find the correct types of chemicals, and to try them out in full-scale tests. Note: Coke plants have informed us that highly aromatic solvents such as toluene can dissolve asphaltenes. However, of different reasons these chemicals need to be avoided. Note: We do not find the same cleaning problem after discharge of calcined petcoke, most probably because calcination of the raw petcoke burns off all the pitch.

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5. What is Green Delayed Petcoke? INTERNET: Petroleum Coke (Petcoke): A residue high in carbon content and low in hydrogen that is the final product of thermal decomposition in the condensation process in cracking. This product is reported as marketable coke or catalyst coke. The conversion is 5 barrels (of 42 US gallons each) per short ton. Coke from petroleum has a heating value of 6.024-mil Btu/bbl. Petroleum coke is used in a similar fashion to coal. Its heating value exceeds 14,000 British thermal units (Btu)/pound. Coal usually is found in the 8,000 to 13,500 Btu/pound range. The higher Btu content of petrol-eum coke makes it very attractive from a cost standpoint. Because it takes less total tons of petroleum coke to achieve the desired heat input, transportation costs drop. Petroleum coke also has a lower ash content than coal, which reduces the problem of bottom ash disposal and particulate the collec-tion. Coal is a higher quality product, however, and if the price is right, buyers choose coal over petroleum coke every time. The way petroleum coke was used up until a couple of years ago was strictly on a micro-basis, where someone might have a boiler, cement kiln or steam boiler for making electricity in relative proximity to a refinery and their emissions limit or technology would allow them to use a certain percentage of this product in their blend. The proximity of refineries to power plants also influences the amount of petcoke purchased for use in electricity generation. This is a win/win for both the refinery and the power plant, because it gets the petcoke off the refinery's property and results in a "cheap” form of fuel for the power plant. In the past few of years, there has been an increase in the amount of petcoke produced and because of that you had some more aggressive marketing of the product made to people who operate coal-fired generating plants. It could go to a plant that has a scrubber or large amounts of low-sulphur coal to blend into a high-sulphur product such as petcoke. EXPORTER (Green Delayed Petcoke = Green Petcoke): Moisture/Water content = normally 8-10 % Loading temperature = normally ambient Sulphur content fuel grade = 3,5 – 7 % For further information, ref.: Cargo Description attached.

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BIMCO (ref.: www.bimco.dk ): There are basically three types of pet coke produced, depending on the process of production. The three processes are delayed, fluid and flexi coking, with delayed coking producing over 90%. All three types of petcoke have higher calorific values than coal and contain less volatile matter and ash. The two most important qualities are "green coke" and "calcinated coke". Green delayed petcoke is normally used for cement production. Green delayed coke (or sometimes called raw coke) is a commonly used term for a primary carbonization product from high-boiling hydrocarbon fractions (heavy residues of petroleum or coal processing) produced by the delayed coking process. Green delayed coke could be sold as it is for immediate use. Or it may go through a further process of purification or calcination, ie. the petcoke is further processed by burning, forming calcined coke, which is normally transported hot. Based on the above, I guess you could say that delayed green coke and calcined green coke are the SAME type of coke but of DIFFERENT grade separated by the calcination process. TORM (ref.: www.torm.dk): Green Delayed Petroleum coke Petroleum coke (petcoke) is a residual by-product of oil refining process. Residue components of heavy crude oil is used as feedstock in thermal cracking process known as coking to produce lighter fuels. It is heated to about 475 degrees centigrade to 520 degrees centigrade in a furnace, and is then discharged into a coke drum for extensive and controlled cracking.

The cracked lighter product rises to the top of the drum and is drawn off. The heavier product remains and, because of the retained heat, cracks ultimately to coke, a solid carbonaceous substance akin to coal, known as petcoke.

Decoking is accomplished by a high-pressure water jet. First the top and bottom heads of the coke drum are removed. Next a hole is drilled in the coke from the top to the bottom of the vessel. Then a rotating stem is lowered through the hole, spraying a water jet sideways. The high-pressure jet cuts the coke into lumps, which fall out the bottom of the drum for subsequent loading into trucks or railcars for shipment.

Cokers produce no liquid residue but yield up to 30 percent petcoke by weight. Much of the low-sulphur product is employed to produce electrodes for the electrolytic smelting of aluminum. Most lower quality coke is burned as fuel in admixture with coal.

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Usage of Petcoke for Chinese customers Most of the imported Petcoke (petroleum coke) is used for burning as the fuel materials like power generation, silicon melting, cement industry. This kind of Petcoke normally have high sulphur, metal content, also have high shot coke content (over 30%, some of them is 100% shot coke). Cargo receiver: Power plant in Spain:

Petcoke is also widely used to produce Calcined Petroleum Coke (CPC), which will be used to produce Pre-baked Anode or Graphite products. These kinds of petcoke should be sponge coke with low sulphur, ash and metal content. Calcined Petroleum Coke(CPC) Petroleum Coke Calcining is a process in which green coke is subjected to temperatures in the range of 1200-1350 degrees centigrade to

remove moisture and volatile combustion matter. This process upgrades the coke to nearly pure carbon. The aluminum industry, which utilizes Calcined Petroleum Coke (CPC) in the reduction of bauxite to aluminum is by far the largest consumer of this product. Over 70% of CPC production goes into the production of carbon anodes for this reduction process. Substantial quantities of CPC are also used in the production of titanium dioxide. Approximately 8% of total CPC production goes into the ferrous foundry recarburizer market. Petroleum coke 1.What's the difference between fuel grade Petcoke and Anode grade Petcoke? Fuel grade Petcoke is mainly used for Power generation, Cements Industry and Silicon melting as the materials of Fuel. Anode grade Petcoke is mainly used for Calcining with products of CPC (Calcined Petroleum Coke), which will use for producing of Pre-baked anode and Graphite. Fuel grade Petcoke have high HGI and metal content, mostly with high Shot coke content, Anode grade Petcoke normally with High HGI, Low metal content, 100% sponge coke. Calcined Petroleum coke-CPC What's the usage of CPC (Calcined Petroleum coke)? CPC can be used for producing Aluminium Anode, Graphite, etc. according to the different grade. After calcining of GPC (Green Petroleum coke), CPC have the low Ash, V.M, Moisture, and high real density characteristic.

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For further information, ref.: www.sinowaypetro.com, www.petcokes.com, www.glcarbon.com and www.coking.com 6. Lab analysis & tests To find a solution to the problems after transporting cargoes such as Green Delayed Petcoke, we have made lab analysis of the cargo, and also carried out some small and full-scale tests. These have given us a better understanding of the cargo and the correct type of chemical to be recommended. The lab analysis show that the cleaning problems after discharge of Green Delayed Petcoke are not so much caused by stains of oil, but more from remaining colour pigments / pitch caused by the temperature, pressure and condense during sea voyage / transport. For further information, ref.: documentation below. First test (responsible: Gunilla Johanson) Form: Black powder and lumps

Green Delayed Petcoke consists of: Residue component of heavy crude oil in cracking process. Nearest substance I know is asphalt. Solubility: Tests were performed with ethanol, gasoline, T-Grön and Li 200. 1 g Green Delayed Petcoke was mixed with 50 ml solvent. The mixtures were left over night. The day after we stirred the mixtures and notified the time it took for the mixtures to be clear.

Results: Solvent Solubility Time to be clear Ethanol Very poor Approx. 1 min Gasoline Very poor 1 min 40 s Li 200 Poor 2 min 10 s T-Grön Poor 2 min 45 s

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Mixtures after blending: Mixtures after 3 min. resting:

Mixtures after 1 hour resting:

Conclusion: Green Delayed Petcoke is very difficult to dissolve. T-grön seems to be the best alternative. I have not done any tests with heating, maybe that can be the trick.

Second test (responsible: Gunilla Johanson) Analysis of solubility, Green Delayed Petcoke Tested products: Aquaclean HD Industrivask Performing: 1 g Green Delayed Petcoke was mixed with 50 ml of each product and was left over night. Following day we stirred the mixtures and notified the time it took for the mixtures to become clear. Results: Product Solubility Time to be clear Aquaclean HD Poor 2 min 30 s Industrivask Poor 1 min 20 s The mixtures were after that heated on water bath for approx. 30 min (90°C).

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Results: For Aquaclean HD it was no bigger differences. Maybe a little more Petcoke was solved. Industrivask was separated in two layers. Small particles of Green Delayed Petcoke stayed in the layer on top, but more heavy sank to the bottom.

After standing overnight: After blending:

After resting for 10 minutes: After heating:

Conclusion: Aquaclean HD seems to solve Green Delayed Petcoke better than Industrivask. Heating has an interesting effect on Industrivask, but it is hard to tell what happens in practice. The times it takes for the mixtures to be clear shall not be compared with the times in previously tests because it is a very subjective judgement. Note: It should be remembered that the tests performed by Gunilla Johansson are all very subjective, neither can the two different tests be compared.

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Third test (Responsible: Silje Bjorlykke) Test of Different Detergents on Painted Plates Soiled with Green Delay Petcoke The aim of this experiment was to test which cleaning effect different detergents had on painted plates soiled with Green Delayed Petcoke (GDP). Method To make the surface as similar as possible to the one found in cargo holds, painted metal plates were used in the test:

• Jotamastic 87, Yellow 2 - normally used to paint the cargo holds • Conseal Touch up, Yellow 2 – used for cosmetic reasons to repaint discolorations and stains

The plates were placed in plastic boxes. Under each plate a glass bowl were placed, to raise the plates from the bottom of the boxes (see picture 1) and to avoid the plates and the Green Delayed Petcoke (GDP) to be in direct contact with the water. The plates then were rubbed with GDP, and a centimetre thick layer of GDP was put over the plates (see picture 2). Finally water was poured into the boxes (see picture 3).

Picture 1 Picture 2 Picture 3 The boxes were left in a heater at 55°C for 11 days (see picture 4). The water and the heat were used to simulate the warm and moist weather to which the cargo can be exposed.

Picture 4 After 11 days the plates were taken out of the heater and the loose GDP was shaken of. The plates then were put in a vertical position. First 5 ml of a 2 % solution of four different products were poured on the plates with pipettes. The products tested were Titan Industri, P3 Redskapsvask, Addi SU 931 and TASKI R20 plus. Afterwards 5 ml of a 5 % solution of the two products who earlier gave the best result were tried; Titan Industri and P3 Redskapsvask.

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Results Already after turning the plates up-side-down to shake of the GDP we could see a great difference between the two types of paint. On the plates painted with Jotamastic 87 the GDP fell easily of, leaving only a thin layer of black dust and grease (see picture 5). On the plates painted with Conseal Touch up the GDP hardly fell of at all. A thick layer of GDP remained on the plates, and force had to be used to scrape of the residues. Even after this a hard layer of GDP remained on the plates (see picture 6).

Picture 5 Picture 6 P3 Redskapsvask and Titan Industri seemed to give the best result on plates painted with Jotamastic 87 (see picture 7). But the cleaning results were not satisfactory, and because of this the strength of the solutions were increased from 2% to 5 %. Still some sort of fatty film remained on the plates, but this was easily removed with a soft touch with a finger (see picture 8). P3 Redskapsvask gave the best wetting of the two products. On the plates painted with Conseal Touch up it was impossible to remove the GDP (see picture 9). It remained as a rough, stone like surface, and the GDP seemed to be burned into the paint. After scrubbing with a rough pad, some of the GDP was removed together with the paint itself. Jotamastic 87 did not loosen from the plate when scrubbed with a pad.

Picture 7 Picture 8 Picture 9 Conclusion The plates painted with Jotamastic 87 was satisfactory cleaned with both products; P3 Redskapsvask and Titan Industri (see picture 10). It seemed like P3 Redskapsvask gave the best result, because it spread more easily on the plate (better wetting). But to give a good cleaning result, the chemicals had to be combined with a light physical touch on the surface (light scrubbing with finger). Because of this it seems necessary to use cleaning equipment, which makes the water hit the surface with a certain force. But the best result would probably be achieved using brushes. Cleaning chemicals alone is not enough. The plate painted with Conseal Touch up was impossible to clean at all (see picture 11). Rough scrubbing made the GDP loosen, but together with the paint.

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Picture 10 Picture 11 The biggest difference can be seen between the two types of paint. Jotamastic 87 remained hard, and the GDP did not stick to it. The GDP could easily be removed with detergent and light scrubbing. Conseal Touch up seemed softer and more porous, and the GDP fastened to it in big lumps. Even after hard scrubbing, the GDP did not loosen. In a previous experiment the same test were preformed, but on plates of stainless steel. On stainless steel the GDP was washed away even without touching the plate. Our recommendation is to try P3 Redskapsvask in practice in the cargo holds concerned. Correct test results are only achieved under real test conditions. It might be that the plates were treated under more extreme circumstances in this experiment, than in real life. 6.1. Comments As mentioned already, we do not seem to have this difficult cleaning problem after discharge of calcined petcoke, most probably because calcinations of the raw petcoke burns of all the pitch. Consequently, to give us a better understanding of the cleaning problem, it is important to know what “pitch” really is. Quote Pitch is a carbonaceous, tacky residue resulting from distillation of coal tar, petroleum, pine tar and fatty acids. Some types such as glance pitch occur naturally. They are used chiefly as seals, roofing compounds or wood preservation. In papermakers’ terminology, a mixture of calcium carbonate, calcium soaps from wood components, and miscellaneous residues from materials used in paper manufacture. Unquote Note: According to this, pitch can best be translated with the Norwegian words “bek” and “kvae”. 7. Solutions to the problems A possible solution to these problems is a combination of correct choice of chemicals and powerful cleaning equipment. We may find that onboard some vessels (which need the cargo holds to be “Hospital Clean”), it may be cost-effective to use a Prewash or Barrier type of chemical.

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Full-scale tests of protective chemicals have now been carried out onboard several bulk carriers of Open Hatch design, and a final report from these tests is expected late summer 2004. New cleaning chemicals have also been tested out.

Note: Bulk carriers with open hatches and double skins are easier to clean compared with cargo holds of the conventional construction. However, the main trade of these vessels involves very sensitive cargos and a cleanliness of cargo holds much higher than grain (“Hospital Clean”). Consequently, if cleaning chemicals are effective for bulk carriers of Open Hatch design, vessels of the conventional construction will be covered as well. 8. Chemicals 8.1. Cleaning chemicals Cost effective cleaning procedures depend on the correct choice of Chemicals, Equipment and Know How. Exchange of Opinions and Documentation between all of us will make it easier to operate bulk carriers from “black to white”, and to solve the cleaning and maintenance problems of stains or “footprints” of black cargoes such as Green Delayed Petcoke. Our main target at Stromme is to “SaveYou Time”. Only by doing this we believe we can add a profit to our bottom line and be successful in the years to come. Hopefully, in the end we will find Time Saving and Cost Effective Solutions to the present Cargo Hold Cleaning Problems. Correct choice and use of cleaning chemicals is necessary for the final result. The cleaning chemicals should be applied as white and wet foam. Applied as white, it is more easily to see from tank top level that we have covered all parts of the cargo hold. Applied as wet foam, the chemicals will have a longer working time before drying and thus be far more effective. The chemicals should dissolve footprints of the cargo and thus make the following cleaning by powerful air/water nozzles from tank top level or high pressure cleaners from crane baskets / working platforms easier. Ref.: photos.

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The use of hot water will increase the dissolving effect of cleaning chemicals. However, we all know that large amounts of hot fresh water are not available onboard bulk-carriers. Hot water can be provided by portable high pressure cleaners, but this equipment requires close up working baskets / platforms.

Note: Aromatic solvent-based degreasers can dissolve most types of oily stains. However, these chemicals may give problems to the strict non-polution controls, and they will create smell and vapour. When trying to find a possible solution to the Pitch problem, type/system of hold paint also needs to be considered. Today, modified epoxy paint (Mastic types) is most commonly used to protect the cargo holds. Unless a topcoat of pure epoxy is applied, strong chemicals should be treated with care. For cosmetic reasons, some owners use to repaint the cargo holds with acryl products. The resistance of these types of paints is acceptable against alkaline chemicals (if treated with care), but strong solvents will dissolve the paint. Aluminum paint is not so much used today. However, it should be remembered that use of strong alkaline chemicals must be avoided.

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8.2. Prewash / Barrier chemicals Prewash chemicals are applied prior to loading of difficult to clean cargoes to save time and costs during the following cleaning operation. Barrier chemicals are used to protect the cargo hold paint if a very high standard of cleanliness is required, or to protect the cargo holds from corrosion. Note: Wrong choice or use of chemicals may give paint problems.

9. Equipment We all know that chemicals can only solve “half the cleaning problem” after discharge of cargoes such as Green Delayed Petcoke. We also need powerful cleaning equipment to be used from tank top level or from hatch baskets. As time at port is shorter and shorter, and cranes cannot easily be used during sea voyage, cleaning of cargo holds should preferably be performed from tank top level. Maxi-Gun in use: Powerful cleaning of the upper parts: Note: The cleaning effect of such equipment requires a minimum of pressure and flow of the general service pumps, the air compressor and the dimensions of the deck pipes. Pressure drops should be calculated and simple and cost effective improvements such as increasing the diameter of water and compressed air couplings should be evaluated.

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Onboard this vessel (ref.: page 19), maximum pressure of the sea water pumps was 6,4 bar, service air reduced from starting air bottles, and small dimensions of outlets / valves only. The water pressure at tank top level with water only was 2,4 bar, which increased to 4 bar when compressed air was turned on.

High pressure cleaners of 350 to 500 bar should also be part of the standard equipment onboard any bulkcarrier. These are very useful, not only for the reachable parts of the cargo holds, but also to clean and maintain hatches, comings and main deck areas. Hot water cleaners are not so commonly part of ships’ equipment. However, no doubt that these will make the cleaning operation easier and save a lot of chemicals.

10. CONCLUSION During recent months, small and full-scale tests have been carried out onboard quite a number of vessels, all geared and in the range of 15.000 to 40.000 DWT. A few of these have been of the old single skin construction in a trade to be cleaned to a “grain standard”, others have been of the open hatch design with double skin to be cleaned for pulp, a cargo which requires cargo holds to be “hospital clean”.

10.1. The cargo Generally, to clean from black to white from tank top level is not so much of a problem if the vessel has adequate equipment and a sea-stock of chemicals onboard and the crew is well trained for the job. However, all depending on the paint system it should be remembered that cargoes such as Green Delayed Petcoke often cause serious cleaning problems and many days of off-hire. Consequently, when fixing the vessels for this type of cargo lost time and cleaning costs should be considered. So far, we have not found any chemicals, which can dissolve stains of pitch from cosmetic types of alkyd paints to allow us to perform the following cleaning from tank top level, and a protective coating prior to loading this cargo or bleaching of the holds may be the only

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alternative to frequent repainting. However, to find more cost-effective solutions to the problems, tests are still been carried out. Recent full-scale tests show that our cleaning chemical Aquaclean HD applied undiluted as wet foam, remained to be soaking for 15-20 minutes and removed by high pressure cleaners of minimum 300 bar and a good water flow will solve the problem. These tests are considered to be a big step forward.

Note: Left side of the hold has been cleaned and painted with cosmetic paint and right side partly cleaned only. Tests are being carried out with bleaching chemicals, which did not give the same cleaning effect as our Aquaclean HD. Behind thick layers of loose paint, you will also find spots of rust. High pressure cleaning has removed the loose paint, the rust can be seen and taken care of. Cosmetic paints will not protect the steel, but is a method to protect a “white” cargo from being discoloured and the ship to be accepted for this cargo only. Frequent cosmetic repainting will increase the long-term cleaning and maintenance problems of cargo holds. Onboard all vessels we have visited, Green Delayed Petcoke seems to leave a discolouring pattern on the bulkheads at the top of the cargo level. This may have something to do with the loading process (which is practised to avoid too much dust all around), but is more probably caused by the upper parts of the cargo moving during sea-voyage, the humidity and temperature.

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In order to understand the cleaning problems after carrying dry cargoes such as Green Delayed Petcoke, it is important to remember that all grades of petcoke origins from crude oil. Crude oil contains different fractions: 1) oil which also contains sulphur, 2) and resins (pitch), a brown sticky hydrocarbon part, which also contains sulphur, and which is said to be soluble in n-pentane but not in propane. We have different grades of petcoke. Raw or green sponge coke, which gives us the most serious cleaning problems, and calcined petcoke. During calcinations (heating) of the petcoke, the resins (pitch) are being burned off, which is why it is easier to clean after calcined petcoke. It should be remembered that because of the sulphur content of petcoke, not only cleaning but also corrosion may create problems. Rotations of cargoes such as petcoke/coal and salt may give fast attacking rust problems, even though the protective paint is considered to be in a good condition. 10.2. Construction / design As we all know, most bulk carriers are of the old fashioned (single skin design) and not built to transport all sorts of dry bulk cargoes. Neither are these vessels normally being equipped for close-up cleaning and maintenance of the upper parts of the cargo holds during sea voyage.

• Much time is spent onboard t

clean old fashioned bilge systems

o

• Much time is spent onboard because of limited fresh water supply on deck

• Much time is spent onboard because of lack of service air

• Much time is spent onboard because of water and air on deck pipes, couplings, etc. being too small

During recent years, operators have become more and more effective and ballast trips are shorter and shorter, and because of the new security rules less deckhands are available for cleaning during vessels stay at port. Not only the new security rules, but also frequent visits by class authorities, port states controllers, etc. make time for hold cleaning during stay at port shorter and shorter.

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More and more, preparing the cargo holds for the next cargo has to be performed from tank top level during sea voyage with closed hatches! 10.3. Paint systems Generally, the more glossier the paint the more easier it is to clean. Today, modified epoxy seems to be the most common paint used for cargo holds, but in the pulp trade many vessels frequently repaint the holds with cosmetic types of fast drying acryl paints to meet the requirements of the exporter. Note: It should be remembered that these cosmetic fast drying paints are not only difficult to clean but also sensitive to strong chemicals. Strong alkaline detergents and strong aromatic solvents have to be avoided. These paints are applied of cosmetic reasons only and even when cleaning at a distance from tank top level the cosmetic paint may easily be removed. We have seen both from lab tests and full scale tests that Green Delayed Petcoke (Pitch) is very difficult to remove from some types of paints. It seems to be “burned” into the paint, and unless a second cleaning heavily activated with brushes is performed, to be “bleeding” from the inside of the paint.

We have also seen that frequent cosmetic repainting may increase the cleaning and maintenance problems. Behind loose paint it may be difficult to clean even by heavy brushing, and we will find rust. In the long run, cosmetic repainting may be a costly solution to unsolved cleaning problems. Note: In the end, complete removal of old paint will be the only and a costly alternative.

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Chemicals Cleaning chemicals To remove discolouring from Green Delayed Petcoke, different cleaning chemicals have been tested, strong caustic alkaline ones as well as strong solvents. So far, we have not found any cleaning chemical, which can solve the problem in a good way (which makes it possible to carry out the cleaning from tank top level with closed hatches). The cleaning problem of this cargo seems to be more from colour pigments “burning” into the paint rather than from stains from oil. Bleach chemicals Still, we consider bleaching to be an alternative to frequent repainting onboard some types of vessels. However, remember that bleaching must not be compared to cleaning, because after some time the stains will appear again. Bleaching may solve the immediate problem to be accepted for a “white” cargo. Protective chemicals If cleaning is to be performed from tank top level, use of protective chemicals in combination with strong alkaline detergents seems to be the only alternative. However, it should be remembered that chemicals such as our Fat Cargo Slip must be applied as described, our Aquaclean HD has to be applied fairly concentrated, and powerful Maxi-Gun cleaning is necessary.

Note: It should be remembered that cleaning chemicals need to be removed before drying on the surface. If not, you may face an even bigger problem, which is not commonly known by our seamen. Applied as wet foam the chemicals will have a longer working time and be far more effective.

Equipment Generally, bulk carriers are not designed for carrying all the different dry bulk cargoes and not well equipped for preparing and cleaning the cargo holds from “black to white”. Shipyards seem to avoid proposals to new designs, owners and management companies try to avoid investments, and operators will not pay as many ships are on a short-term charter only.

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It should be remembered that use of strong chemicals only is not sufficient to clean the cargo holds. The cleaning result will depend on a correct choice and use of chemicals and the use of powerful equipment, used from tank top level or at close distance from working platforms or crane baskets.

All depending on the paint, discolouring from pitch seems to be solved by chemicals and use of high-pressure cleaners (300 bar and upwards) or heavy brushing. Remember that these high-pressure cleaners will need a good water flow.

As a rule of thumb, our Mari-Clean high-pressure cleaners are recommended when cleaning at port, whilst our Maxi-Gun air/water cleaning nozzles are the most powerful alternative for cleaning during sea voyage with closed hatches.

Do not forget underneath the hatches! High pressure blasting of rust spots with injection of sand prior to repainting.

10.4. Know how & Procedures To perform cost effective cleaning and maintenance of cargo holds, the crew needs to be well trained for the job. Extracts from the ISM code chapter 15: The company shall provide the ship with general reference information about cargoes, which are regurarly carried in ships trade. The company shall assist the master in obtaining special information about a particular cargo and shall advice him of any special precautions to be taken.

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The company shall establish and maintain procedures to ensure that the ship is technically fit and prepared for the intended type of cargo. Note: To establish safe and cost-effective cleaning procedures, it is necessary to provide the Master with a description of the cargo including Material Safety Data Sheets of the cargo and the chemicals to be used. 10.5. It is possible!!!

No doubt that it is possible to clean and prepare the cargo holds from “black to white” with ships’ own crew. However, it should be remembered that necessary time should be allowed for the cleaning operation, the

vessels should be well equipped, the crew trained for the job, and a sea-stock of chemicals should be carried onboard. However, first of all charters should avoid difficult cargoes or rotations of cargoes if the paint is not suitable for the cargoes to be carried. Opposite to tankers, which are carrying all types of wet cargoes in bulk such as crude oil and all types of chemicals, most dry bulk carriers are of the old fashioned design/construction, not equipped from the ship yard or the owner to carry out cost effective cleaning and/or maintenance of the cargo holds, and access problems and choice of hold paint give serious problems when a bulk carrier is fixed for a cargo such as Green Delayed Petcoke. Hopefully, paint manufacturers will put more efforts into developing fast drying and glossier paints suitable for maintaining holds of bulk carriers. Hopefully, sometime in the future shipyards will give the cleaning of cargo holds some considerations when designing dry bulk carriers. To make the life of our seamen easier, only small changes are necessary. Hopefully, ship owners will realise that when ordering a new ship, which are designed to be trading for 25 to 40 years, it is necessary with access to the upper parts of the cargo holds and small investments in cost-effective hold cleaning will be accepted.

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Hopefully, more and more operators of dry bulk carriers will find that the vessels need to be well equipped and the crew trained for the job. If not, charters have to be more selective when fixing the ship for a new cargo. Meanwhile, charters will have to calculate + 5 to 10 days for the cleaning operation when fixing their vessels for cargoes such as Green Delayed Petcoke.