Quarterly September 2007 - Odfjell
Quarterly September 2007 - Odfjell Quarterly September 2007 - Odfjell
What they actually doTank Cleaning OperationsBy Torger Trige, Cargo Handling AdvisorTank cleaning is oneof the jobs that arecarried out very frequentlyon boardchemical tankers,as such ships alwayshave to presentload-readytanks, completelyvisually clean, dryand odourless, before loading. This isnormally referred to as a water whitestandard cargo tank, and is regardedas a minimum requirement for loadingchemicals. In case of delicate high puritychemicals, such as potable ethanol ormethanol, tank cleaning will continuebeyond water white standard, in orderto be prepared for wall wash testing.Wall wash with subsequent analysis ofthe samples in a laboratory is an establishedway in our industry to determinethe cleanliness and thereby the suitabilityof a cargo tank for carriage of delicatecargoes. A wall wash sample is collectedby running a certain amount ofpure solvent down the bulkheads insidethe cargo tank. The test criteria variesdepending on the cargo to be loaded,but commonly they aim at detectinghydrocarbons, chlorides, colour, smellor specific cargo residues in the sample.Our ships are normally equipped withbasic laboratory equipment, to enableChief Officer Legada and Bosun Abellen preparing for spraying a tank withdeionised waterthe crew to check the tanks’ suitabilitybefore presenting them for surveyor inspectionin the load ports.In general terms, a cleaning operationnormally consists of cleaning with waterat suitable temperatures accordingto last cargo properties. If needed it isfollowed by cleaning with detergentsand another round of water cleaning.Ventilation, fresh water rinse and dryingare also carried out as necessary, andyou keep on repeating the routine untilachieving the desired result. The trickypart is to find the appropriate watertemperatures, the correct type and dosageof cleaning compound, the optimallength of time for machine cleaning,determine the necessary use of manualwork and last but not least, assess thesafety of the operation. Cargo properties,such as water solubility, solubilityin cleaning chemicals or solvents, meltingpoint, drying properties (vegetableoil), viscosity, sediment problems, toxicdangers, flammability and coating restrictions,are vital decision factors consideredto be basic knowledge to eachand everyone involved with cargo operations.By and by this is worked intothe bone of people on board, makingthem able to make the correct decisionson a cleaning procedure.Bow Puma at anchorage waiting to berth in SantosTank cleaning is a critical operation asdefined by the Odfjell Shipboard ManagementManual. This manual prescribesthe use of established sound routines,several check lists, written plans andpre-meetings before any cleaning operationcan commence. However, there32 Odfjell Quarterly September 2007
Wall wash equipment inside the tankis no secret that the most important factorwhen it comes to safety in any shipboardoperation is skilled people withthorough understanding of the jobas well as the dangers involved. Thereis absolutely no substitute for real lifeexperience when it comes to practicalchemical tanker operation.Tank cleaning machines are used whencleaning a ship’s cargo tanks. They areeither lowered into the tank, typicallyon older vessels, or they are mountedfixed into the tanks. The machines aresupplied with water through rubberhoses from a pipeline on deck, normallyreferred to as the Butterworth line. Thetemperature of the water is regulatedvia a steam heater. There are a numberof other aspects in a cleaning operationthat may be necessary, such as manualcleaning, spraying with deionised waterand steaming, which require the use ofother types of equipment. However, letus not take it too far in this article.In certain cases, where the cleaning isexpected to become very demandingor needs particular procedures, MarineSupport Group can be present on boardto support the crew in carrying out theoperation. Recently I had the pleasureof joining Captain Etrata and his crewon Bow Puma, to assist in a demandingtank preparation before loading full2nd Officer Richie Mejares performing some sample testingcargo of ethanol in Brazil. Previous cargoeswere a combination of lubricatingoils, palm oils, synthetic paraffin andpropyl alcohol. All of the vessels tanksexcept the ones last containing propylalcohol were due for a severe cleaning.As mentioned the test criteria may varydepending on the quality of the nextcargo. In our case the passing of the socalledTyndall test and chloride test wasmandatory for all the ethanol grades. Inaddition, the tanks scheduled to holdhigh grade ethanol were tested withUV-test and non-volatile matter test.For the very first time we had a UV-meteron board for trial and thus, we wereable to do the UV-scan prior to presentingthe tanks.The wall washes we collected after theinitial water cleaning left us with nothingbut disappointment. The cleaningwas continued as a round the clock activity.Depending on the tasks at handwe sometimes worked long days withthe whole deck crew, but in most caseswe split the deck crew into two groupsand continued 24 hours a day in a sixhours on/off system. The engine crewwas also working around the clock in asimilar pattern while the cleaning wasgoing on, due to the massive powerconsumption and the constant use ofsteam.After 16 days of cleaning we arrived inSantos with all 27 ethanol tanks readyfor inspection. The inspection, wallwash collection and subsequent analysistook several hours and involved anotherround of procedures, check lists andpre-briefings before doing the actualjob. All the tanks passed and the loadingwent on without any problems. Welldone Bow Puma!Wall wash samples seriously failingthe Tyndall testCleaning chemicals stored on deckOdfjell Quarterly September 2007 33
- Page 2: In this issue:P.O. Box 6101 Postter
- Page 21 and 22: Bow Octavia and Bow OliviaBy Frode
- Page 23 and 24: The process concept inquality manag
- Page 25 and 26: By Toralf SørenesEnclosed SpacesEn
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What they actually doTank Cleaning OperationsBy Torger Trige, Cargo Handling AdvisorTank cleaning is oneof the jobs that arecarried out very frequentlyon boardchemical tankers,as such ships alwayshave to presentload-readytanks, completelyvisually clean, dryand odourless, before loading. This isnormally referred to as a water whitestandard cargo tank, and is regardedas a minimum requirement for loadingchemicals. In case of delicate high puritychemicals, such as potable ethanol ormethanol, tank cleaning will continuebeyond water white standard, in orderto be prepared for wall wash testing.Wall wash with subsequent analysis ofthe samples in a laboratory is an establishedway in our industry to determinethe cleanliness and thereby the suitabilityof a cargo tank for carriage of delicatecargoes. A wall wash sample is collectedby running a certain amount ofpure solvent down the bulkheads insidethe cargo tank. The test criteria variesdepending on the cargo to be loaded,but commonly they aim at detectinghydrocarbons, chlorides, colour, smellor specific cargo residues in the sample.Our ships are normally equipped withbasic laboratory equipment, to enableChief Officer Legada and Bosun Abellen preparing for spraying a tank withdeionised waterthe crew to check the tanks’ suitabilitybefore presenting them for surveyor inspectionin the load ports.In general terms, a cleaning operationnormally consists of cleaning with waterat suitable temperatures accordingto last cargo properties. If needed it isfollowed by cleaning with detergentsand another round of water cleaning.Ventilation, fresh water rinse and dryingare also carried out as necessary, andyou keep on repeating the routine untilachieving the desired result. The trickypart is to find the appropriate watertemperatures, the correct type and dosageof cleaning compound, the optimallength of time for machine cleaning,determine the necessary use of manualwork and last but not least, assess thesafety of the operation. Cargo properties,such as water solubility, solubilityin cleaning chemicals or solvents, meltingpoint, drying properties (vegetableoil), viscosity, sediment problems, toxicdangers, flammability and coating restrictions,are vital decision factors consideredto be basic knowledge to eachand everyone involved with cargo operations.By and by this is worked intothe bone of people on board, makingthem able to make the correct decisionson a cleaning procedure.Bow Puma at anchorage waiting to berth in SantosTank cleaning is a critical operation asdefined by the <strong>Odfjell</strong> Shipboard ManagementManual. This manual prescribesthe use of established sound routines,several check lists, written plans andpre-meetings before any cleaning operationcan commence. However, there32 <strong>Odfjell</strong> <strong>Quarterly</strong> <strong>September</strong> <strong>2007</strong>
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