INTERTANKO UK Corrosion 2002 – Cardiff, Wales October 24, 2002

INTERTANKO UK Corrosion 2002 – Cardiff, Wales October 24, 2002
CRUDE OIL CARGO TANK CORROSION LADIES & GENTLEMEN, INTERTANKO APPRECIATES THIS OPPORTUNITY TO PRESENT TO THIS AUDIENCE AN UPDATE PAPER ON THE CORROSION OF CRUDE OIL CARGO TANKS. AS SOME OF YOU WILL KNOW INTERTANKO ORGANIZED A CORROSION CONFERENCE IN LONDON 1998 TO HIGHLIGHT AND SHARE INFORMATION ABOUT HIGH PITTING CORROSION RATE OF THE INNER BOTTOM ON DOUBLE HULL VLCCS LESS THAN 5 YEARS OLD. INTERTANKO UK Corrosion 2002 Cardiff October 2002

UK Corrosion 2002 Cardiff 22-24 October 2002
Purpose of this paper Provide a brief background about: Tanker structures and the cargo tank environment Tanker corrosion INTERTANKO’s Corrosion conference Update since 1998 Conclusions – way ahead – coating – access – class rule harmonization – THE PURPOSE OF THIS PAPER IS TO PROVIDE A BRIEF BACKGROUND TO INTERTANKO’S INVOLVEMENT IN THE CORROSION ISSUE. INTERTANKO TOOK THE INITIATIVE TO AN INDUSTRY CONFERENCE ON CORROSION BACK IN OCTOBER 1998. AT THAT TIME SURPRISINGLY DEEP PITTING HAD BEEN DISCOVERED IN NEW DOUBLE HULL VLCCS. THE MAIN REASON WAS THAT SOME NEW DOUBLE HULL VLCCS HAD DISCOVERED VERY HIGH PITTING CORROSION RATE LONG BEFORE THEY HAD PASSED THE FIVE YEAR ANNIVERSARY. OTHERS HAD DISCOVERED HIGHER CORROSION RATES OF THE TANK HEADS – IN THE ULLAGE SPACE, THAN EXPECTED. VARIOUS EVENTS AND DEVELOPMENTS HAVE TAKEN PLACE SINCE THEN DRAWING PUBLIC ATTENTION TO CORROSION, LIKE THE SINKING OF ERIKA IN DECEMBER 1999 AND THE 22 METER LONG MAIN DECK CRACK ON BOARD CASTOR IN DECEMBER 2000. THE PAPER GIVES AN UPDATE AND DRAWS SOME CONCLUSION – OF WHICH THERE IS NOTHING NEW. INTERTANKO UK Corrosion 2002 Cardiff October 2002

INTERTANKO INTERTANKO The International Association of Independent Tanker Owners. INTERTANKO membership represents about 2000 tankers. Chemical, Product and Crude Oil tankers. Offices in Oslo, London, Washington D.C and Singapore. Regional Panels in Americas, the Far East and Greece. BUT LET ME ALSO INTRODUCE INTERTANKO. INTERTANKO IS THE “INTERNATIONAL ASSOCIATION OF INDEPENDENT TANKER OWNERS” WITH OFFICES IN OSLO, LONDON, AND WASHINGTON WITH REGIONAL PANELS IN AMERICAS AND THE FAR EAST. INTERTANKO MEMBERSHIP REPRESENTS ABOUT 2000 TANKERS, CHEMICAL, PRODUCT AND CRUDE OIL TANKERS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

INTERTANKO Examples of INTERTANKO activities: Cooperates with other organisations like OCIMF – ICS – WWF – IACS and numerous others. Active in IMO. Providing factual information. Commenting and working group participation. Active with US Coast Guard. Commenting on proposed rulemaking. INTERTANKO IS AN ACTIVE ORGANIZATION PROMOTING SAFETY AT SEA, TRANSPARENCY, THE CHAIN OF RESPONSIBILITY. INTERTANKO COOPERATE WITH OTHER ORGANIZATIONS LIKE OCIMF, ICS, IACS , WWF AND MANY OTHER. INTERTANKO IS ACTIVE IN IMO, PARTICIPATING IN WORKING GROUPS AND PROVIDES FACTUAL INFORMATION AND OPERATIONAL ASPECTS OF RULE MAKING. INTERTANKO UK Corrosion 2002 Cardiff October 2002

INTERTANKO Keep members advised of political developments and proposed regulatory changes and other issues of general interest – like corrosion. Tanker events – every 6th month Membership criteria – quality Visit Intertanko home page on: INTERTANKO KEEPS ITS MEMBERSHIP ADVISED OF DEVELOPPMENT ON A WHOLE HOST OF ISSUES RANGING FROM POLITICAL ISSUES AND PROPOSED REGULATORY DEVELOPMENTS TO CORROSION AND TANKER MARKET MATTERS, TO MENTION A FEW. INTERTANKO PRODUCES ALONE OR TOGETHER WITH OTHER INDUSTRY BODIES A WIDE RANGE OF GUIDE BOOKLETS FOR USE BY THE SHIP OPERATORS AND OTHERS WITH AN INTEREST IN TANKERS. MORE INFORMATION ABOUT INTERTANKO CAN BE FOUND ON INTERTANKO UK Corrosion 2002 Cardiff October 2002

VLCC - Typical midship section
Approximate Dimensions (in meter): Length over all: 332 Length B. P.: 320 Breadth moulded: 58 Depth moulded: 31 Design draft: 20.8 Scantling draft: 22.0 WHAT DOES A DOUBLE HULL TANKER LOOK LIKE? THIS MIDSHIP SECTION OF A VLCC SHOWS THE BALLAST TANKS SOUROUNDING THE CARGO TANKS. A VLCC WILL HAVE TWO WING TANKS AND ONE CENTER TANK. A SUEZ MAX CRUDE OIL TANKER WILL NORMALLY HAVE WING TANKS, NO CENTERTANK. INTERTANKO UK Corrosion 2002 Cardiff October 2002

VLCC – Double hull Double hull tanker in the building dock Side ballast tank width abt. 2 – 4 meter. Bottom ballast tank height abt meter. Height of centre cargo tank abt. 29 meter Length of centre cargo tank abt. 50 meter THE TANKS ARE ENOURMOUS IN SIZE. TO DO INTERNAL INSPECTIONS IS A MAJOR UNDERTAKING, BOTH DURING CONSTRUCTION AND LATER IN THE SHIPS LIFE. THE OWNER NEDD TO EMPLOY A GOOD AND EXPERIENCED SUPERVISION TEAM TO GET A TANKER AS WELL BUILT AS POSSIBLE. INTERTANKO UK Corrosion 2002 Cardiff October 2002

THENAMARIS -Suez max tanker
THENAMARIS – ONE OF INTERTANKO’S ACTIVE AND FORWARD LOOKING MEMEBERS HAVE BUILT SOME CRUDE OIL TANKERS WORTH SHOWING PICTURES OF. HERE IS SHOWN PART OF AN ALMOST COMPLETED MIDSHIP SECTION OF A SUEZ MAX TANKER TAKEN IN 2000. PLEASE NOTE THE THRE DECKS WITH BULKHEAD ACCESS HOLES FOR INSPECTION OF WING BALLAST TANKS ON BOTH SIDES. THE THREE STRINGER DECKS IN THE CARGO TANKS HAVE ACCESS AND IT SHOULD BE POSSIBLE TO SEE THE RAILINGS ON EACH STRINGER FOR SAFETY DURING INSPECTIONS. NOTE ALSO THAT THE CARGO TANK BOTTOM HAS ALREADY RECEIVED THE FIRST COAT OF CORROSION PREVENTING PAINT - COLORED RED. Notice the red coat on cargo tank inner bottom INTERTANKO UK Corrosion 2002 Cardiff October 2002

Corrosion mechanisms at work
IT IS NECESSARY TO REMIND OURSELVES A LITTLE ABOUT THE CRUDE OIL. THE CRUDE OIL COMES FROM THE OIL WELL IN THE GROUND AND IS TREATED OR STABILIZED IN VARYING DEGREE PRIOR TO BEING LOADED INTO THE SHIP’S CARGO TANKS. ONCE THE CRUDE OIL IS IN THE CARGO TANK THE STEEL IS EXPOSED TO THE CARGO AND WHAT EVER IT MAY CONTAIN OF CORROSIVE ELEMENTS. THE ULLAGE SPACE – TANK HEADS – WILL BE EXPOSED EXTERNALLY TO SUNSHINE AND OUTSIDE TEMPERATURE. THE ULLAGE SPACE WILL CONTAIN VARIOUS AMOUNTS OF ETHANE, PROPANE, BUTANE HYDROGEN SULPHIDE (H2S), CARBON DIOXIDE (CO2), WATER, SOOT FROM THE INERTGAS, SALTY WATER VAPOURS FROM THE INERTGAS SCRUBBER, NITROGEN AND WHATEVER ELSE THE CARGO MAY CONTAIN OR RELEASE OF VOLATILE ORGANIC COMPOUNDS. THE ULLAGE SPACE ENVIRONMENT IS ACID AND PH AS LOW AS ONE (pH 1 HAS BEEN MEASURED, ALTHOUGH A pH AROUND 4 APPEARS TO BE MORE COMMON. THERE IS A MULTITUDE OFFACTORS AFFECTING THE CORROSION MECHANISMS AT WORK ON THE NORMALLY BARE STEEL FOUND IN THE ULLAGE SPACE ON A CRUDE OIL TANKER. IN THE BOOTOM THERE IS OFTEN SOME WATER AND MICROBES OF VARIOUS TYPES. THE DOUBLE HULL ACTS LIKE A TERMO BOTTLE AND THE CARGO STAYS WARMER LONGRER THAN IT USED TO ON A SINGLE HULL TANKER. THIS KEEPS THE MICROBES ACTIVE MUCH LONGER AND THE RISK FOR HIGH PITTING CORROSION HAS INCREASED. THEN THERE IS THE HULL FLEXING, STRUCTURAL STRESSES AND STEEL TYPE USED TO CONSIDER AS WELL. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Volatile/stable crude oil
SOME CRUDE OILS LIKE THE ONE EXAMPLE DESCRIBED TO THE LEFT IS VOLATILE AND GENERATES SIGNIFICANT AMOUNTS OF VOLATILE ORGANIC COMPOUNDS (VOC) THAT WILL BE RELEASED TO THE ATMOSPHERE. INTERTANKO HAS ISSUED GUIDELINES TO TANKER OWNERS AS TO HOW THESE VOC EMMISSSIONS CAN BE REDUCED WITH SIMPLE OPERATIONAL MEASURES. THE EXAMPLE TO THE RIGHT DESCRIBES A STABLE CRUDE OIL THAT “EAT” INERTGAS. TO KEEP THE REQUIRED OVERPRESSURE IN THE ULLAGE TO PREVENT AIR TO ENTER FREQUENT TOPPING UP WITH INERTGAS IS REQUIRED. INERTGAS IS NORMALLY PRODUCED FROM BOILER FLUE GASES PASSED THROUGH A SCRUBBER USING SEA WATER. AN ALTERNATIVE TO FLUEGAS FOR TOPPING UP PURPOSES COULD BE A NITROGEN GENERATOR BASED UPON MEMBRANE TECHNOLOGY. BUT THAT IS NOT USED FOR CRUDE OIL TANKS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Day/Night WHEN THE CRUDE OIL TANKER IS IN BALLAST WITH THE CARGO TANKS EMPTY THEY ARE FILLED WITH INERTGAS AT A SLIGHT OVERPRESSURE PRODUCED FROM THE FLUEGASES TO PREVENT AIR TO ENTER THE CARGO TANKS AND FORM EXPLOSIVE MIXTURES. THE FLUE GAS IS PRODUCED BY COMBUSTION OF HEAVY FUEL OIL IN THE BOILERS. THE FLUE GAS IS COOLED AND CLEANED DURING PASSAGE THROUGH THE SCRUBBER ON IT’S WAY TO THE CARGO TANKS. SEAWATER IS USED FOR SCRUBBING AND COOLING. FROM THE SCRUBBER THE INERTGAS IS EVENTUALLY LEAD TO THE CARGO TANKS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Pitting in the tank bottom plate (MIC)
THE CARGO TANK BOTTOM PITTING THAT HAD BEEN DISCOVERED WERE MUCH DEEPER THAN EXPECTED BACK IN THE MID 1990’S. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Pitting as discovered on new double hull tankers (MIC)
THE PITTING WAS DEEP AND THE CRATER HAD THE HALLMARKS OF MICROBIAL CORROSION OR MIC. INTERTANKO UK Corrosion 2002 Cardiff October 2002

ONE COAT ON TANK BOTTOM COATING APPLIED ON PITTING CORROSION IN PERFECT CONDITION 5 YEARS LATER NO FURTHER PROBLEM EXPECTED THE UNEXPECTED PITTING THAT WAS DISCOVERED AND DISCUSSED DURING THE INTERTANKO KONFERENCE IN 1998 WAS REPAIRED AND COATED AT THE TIME. THE COATING CONDITION HAS BEEN INSPECTED SEVERAL TIMES SINCE AND IS CONFIRMED TO BE IN EXCELENT CONDITION AND EXPECTED TO STAY SO FOR THE LIFE OF THE VESSEL. INTERTANKO UK Corrosion 2002 Cardiff October 2002

RUST FLAKE FROM ABOVE – UNDER DECK CORROSION!
RUST FLAKE COMMONLY FOUND ON CARGO TANK BOTTOM SOURCE; UNDER DECK CORROSION DURING GAS FREEING OF THE CARGO TANKS IT IS COMMON TO FIND RELATIVELY LARGE RUST FLAKES ON THE CARGO TANK BOTTOMS. THESE FLAKES HAVE COME DOWN AS A RESULT OF HULL FLEXING, TANK WASHING AND RUST SCALE TEARED OFF IN THE PROCESS. THIS CONSTANTLY EXPOSES BARE STEEL TO THE CORROSIVE ENVIRONMENT. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Sulphur crystals FULLY FORMED SULPHUR CRYSTALS FOUND ON THE RUST FLAKES FROM THE UNDER DECK AREA OF THE CARGO TANKS THE RUST FLAKES HAVE BEEN EXAMINED IN MICROSCOPE AND TESTED. IT IS CLEAR THAT IT IS FREE SULPHUR CRYSTALLS THAT HAS FORMED AND SULPHUR IS PLENTIFULL IN THE RUST FLAKES. INTERTANKO UK Corrosion 2002 Cardiff October 2002

ERIKA - December 1999 MAIN INGREDIENTS – OLD TANKER – CORROSION –BAD WEATHER – DISTRESS -SINKING – POLLUTION – ALL HANDS SAVED SIGNIFICANT CONSEQUENCES OF ONE TANKER ACCIDENT ACROSS THE INDUSTRY; TWO TRENCHES OF MARITIME LEGISLATION KNOWN AS ; ERIKA I AND ERIKA II WELL, WHY SUCH AN INTEREST IN CORROSION OF CARGO TANK CORROSION? ERIKA, A 25 YEAR OLD 37,000 TDW MALTESE FLAG CLASSED BY RINA TANKER FULLY LOADED WITH FUEL OIL GOT IN TROUBBLE AND SANK IN THE BAY OF BISCAY ON DECEMBER 12, ALL HANDS WERE SAVED, BUT THE FRENCH COAST LINE WAS HEAVILY POLUTED WITH HEAVY FUEL OIL. THE REGULATORY CONSEQUENCES ON THE WHOLE INDUSTRY BY THIS ONE ACCIDENT IS SEVERE. IT HAS RESULTED IN TWO TRENCES OF MARITIME LEGISLATION KNOWN AS ERIKA I AND ERIKA II. IT DOES NOT MATTER WHAT THE INVESTIGATIONS INCLUDING HULL STRENGTH CALCULATIONS SHOWS AFTER THE ACCIDENT, THE SHIP SANK AND SPILLED HER CARGO OF HEAVY FUEL OIL IN BAD WEATHER DUE TO A HULL STRUCTURE SEVERELY WEAKENED BY CORROSION AND LESS THAN SATISFACTORY SURVEYS AND MAINTENANCE FOR YEARS. THE INGREDIENTS ARE CORROSION AND INADEQUATE REPAIRS AND CORROSION PROGRESSINGIN THE MAIN UNCHECKED. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Castor – main deck crack
December 2000; Part of crack Mediterranean – bad weather Fully loaded tanker – Castor developed a 22 meter long crack in the main deck Coastal states refuse port of refuge Castor survives – no cargo spilled – minor regulatory effect Main ingredients – corrosion – bad weather – inadequate surveys and maintenance THE NEXT INCIDENT HAPPENED TO THE 23 YEAR OLD TANKER “CASTOR”. A 30,000 TDW FULLY LOADED TANKER CLASSED BY ABS DEVELOPED A 22 METER LONG CRACK IN THE MAINDECK STRETCHING ALMOST THE WHOLE LEGHT FROM PORT TO STARBOARD SIDE IN BAD WEATHER IN THE MEDITERANEAN. NO CARGO WAS SPILLED AND THE SHIP SURVIVED. HOWEVER, THE INCIDENT HIGHLIGHTED THE COASTAL STATES IN THE AREA REFUSAL TO PERMIT THE CASTOR A SAFE PORT OF REFUGE. THIS POINT IS NOW BEING SOLVED THROUGH IMO. THE MAIN INGREDIENTS WERE AGAIN AN OLD TANKER, SEVERE CORROSION, FULLY LOADED AND BAD WEATHER. AGAIN THE MAIN INGREDIENTS ARE THE SAME. AN OLD SHIP – FULLY LOADED – BAD WEATHER –INADEQUATE SURVEYS AND REPAIRS. THE CORROSION EXPERIENCED ON CASTOR HAS BEEN DUBBED AS “SUPER RUST” AND “ACCELERATED CORROSION”. RUST AND CORROSION IS NOTHING NEW ON SHIPS. SO, WHAT CAN BE DONE TO AVOID THESE TYPES OF PROBLEMS AS THE TANKERS GETS OLDER? INTERTANKO UK Corrosion 2002 Cardiff October 2002

So, what can be done? The answer is a clear NO! There is more than adequate survey regulations in force. If the present survey regimes are followed, that is! More inspections and more surveys….!? IT IS HUMAN TO ADD ON MORE SURVEYS AND MORE REGULATIONS WHEN SOMETHING HAS GONE WRONG. RULES AND REGULATIONS HAVE EVOLVED OVER TIME, MAINLY AS RESPONSES TO EVENTS THAT TOOK PLACE, OFTEN UNEXPECTED LIKE ACCIDENTS ALWAYS ARE. ALL SHIPS ARE DESIGNED TO A SET OF MINIMUM CRITERIA IN ACCORDANCE WITH CLASS RULES AND OTHER INTERNATIONAL CONVENTIONS. THE MAIN SURVEY CYCLE IS BASED ON FIVE YEARS INTERVALLS BETWEEN COMPREHENSIVE SOCALLED SPECIAL SURVEYS. THERE IS THEN A REGIME OF SURVEYS DURING THE PERIODE. ANNUAL SURVEY, INTERMEDIATE SURVEY BETWEEN THE SECOND AND THIRD YEAR FOLLOWED BY THE FIFTH YEAR SPECIAL SURVEY. DEPENDING ON THE CONDITION FOUND IT IS POSSIBLE FOR CLASS TO REQUEST ANNUAL SERVEY WHERE FOR EXAMPLE BALLAST TANK COATING HAS BROKEN DOWN AND STEEL IS CORRODING AWAY. THE CLASS CAN ALSO ISSUE “CONDITION OF CLASS” WITH A TIME LIMIT TO CORRECT THE SITUATION. IF THE DEFICIENCY IS NOT DEALT WITH WITHIN THE TIME LIMIT THE SHIP MAY LOOSE CLASS. THE END CONSEQUENCE IS THAT THE VESSEL IS UNABLE TO TRADE LEAGLLY. THERE HAVE BEEN MANY CASES IN THE PAST WHERE THE TECHNICAL CONDITION HAS CAUSED SHIPS TO “JUMP CLASS AND FLAG” TO MORE TOLLERANT CLASS SOCIETIES AND FALGSTATES WITH LESS STRICT SAFETY STANDARDS. THIS HAS CHANGED IN RECENT YEARS AND CLEAR RULES ARE NOW IN PLACE FOR HOW TO CHANGE A SHIPS CLASS BETWEEN THE IACS MEMBERS. IN CONCLUSION THERE ARE LONG ESTABLISHED SURVEY RULES AND REGULATION IN PLACE AND THESE HAVE BEEN IN PLACE FOR MANY YEARS. THE PLAIN TRUTH IS THAT CORROSION IS NOTHING NEW. SURVEYS AND REPAIRS MUST BE CARRIED OUT IN A PROFESSIONAL MANNER AND AS INTENDED IN EXISTING REGULATION. CARRY OUT SURVEYS AND REPAIRS AS INTENDED! NOTHING MORE – NOTHING LESS! INTERTANKO UK Corrosion 2002 Cardiff October 2002

What else can be done? Identify risk areas at the design stage Arrange access at newbuilding stage Apply suitable coating to areas of concern like all cargo tank tops and inner bottoms Produce inspection manual THESE COUNTERMEASURES MUST BE COMPULSORY MEASURES – EXEMPT FROM COMMERCIAL PRESSURE! THERE IS NO LACK OF KNOWLEDGE ABOUT CORROSION OR HOW TO DISCOVER IT AMONG THE CLASS SOCIETIES AND SHIP OWNERS/MANAGERS WITH EXPERIENCED STAFF. RISK AREAS IN THE TANKER STRUCTURE CAN BE IDENTIFIED AT THE DESIGN STAGE. ACCESS CAN BE ARRANGED APPLYING A BIT OF INGENUIETY. INSPECTIONM MANUALS MUST BE PRODUCED EXPLAINING AND PINPOINTING TO AREAS IN THE STRUCTURE WHERE INSPECTIONS ARE NEEDED AND WHY. THE INSPECTION MANUAL MUST ALSO EXPLAIN HOW TO ACHIEVE SAFE ACCESS. SUITABLE COATINGS ARE AWAILABLE FROM REPUTEABLE AND EXPERIENCED MANUFACTURERS AND CAN BE APPLIED IN TOP AND INNER BOTTOM – THE PLACES WHERE THE ENVIRONMENT IS PARTICULARLY CORROSIVE. THEN, WE MUST NOT FORGET THAT THERE IS THE COMMERCIAL ELEMENT – COATING AND ACCESS NEEDS ADDITIONAL INVESTMENT, OR IN AN ACCOUNTANTS TERMINOLOGY – “EXTRA COST”. COMPULSORY REGULATION IS NEEDED TO LEVEL THE PLAYING FIELD AND REMOVE THE TEMPTATION TO MAKE SHORT CUTS IN THE NAME OF POLLUTION PREVENTION. COMPULSORY REGULATION MUST INCLUDE PERMANENT ACCESS TO STRUCTURES FOR INSPECTION AND APPLICATION OF SUITABLE COATING IN THE TOP OF THE CARGO TANKS AND THE INNER BOTTOM. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Stress analysis GRAPHS LIKE THIS CAN EASILY BE PRODUCED USING COLOR CODES TO VISUALIZE THE STRESS LEVEL. AREAS OF HIGH STRESS LEVELS CAN BE REDESIGNED TO LOWER THE STRESS. PERMANENT ACCESS CAN BE ARRANGED TO THOSE LOCATIONS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

AREAS VULNERABLE TO CORROSION
These are the areas in a tanker that are likely to suffer corrosion during its service life. Well known! But no permanent access. THE AREAS OF CONCERN IN A TANKER STRUCTURE IS VERY WELL KNOWN AS ILLUSTRATED HERE IN A CUT FROM A TANKER STRUCTURE COOPERATIVE FORUMS GUIDES. THE ONLY ACCESS TO DATE IS BY FILLING THE TANK BY SEAWATER AND USING RAFTS, OR VERY COSTLY AND EXTREMELY TIME CONSUMING WORK IN BUILDING STAGING FOR ACCESS DURING DRYDOCKING. ARGUMENTS AGAINS PERMANENT ACCESS IS THAT IT IS; DANGEROUS AS IT WILL CORRODE. TRUE. BUT THERE IS ALSO NON METALLIC MATERIALS AVAILABLE! IT IS ALSO POSSIBLE TO ENLARGE OR MODIFY LONGITUDINALS ON NEWBUILDING TO ALSO BE USED AS ACCESS PLATFORMS WITH RAILS. THE COST TO THE INDUSTRY IS SIGNIFICANT BY NOT HAVING THE ACCESS – OF WHICH ERIKA AND CASTOR ARE JUST TWO EXAMPLES. INTERTANKO UK Corrosion 2002 Cardiff October 2002

No access Arrows indicate where access is necessary for meaningful close up inspection. Notice no access arrangement Tank inner bottom not coated IN A TANKER STRUCTURE THE ARROWS HERE INDICATE THE AREAS WHERE ACCESS IS REQUIRED TO DISCOVER CORROSION. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Practical logistical problems!
100% survey of a VLCC would require: Height to climb 11 km Area to survey m2 Length of weld km Length longitudinals 58 km Bottom area m2 1,0 % pitting pits TO INSPECT A VLCC IS A MAJOR UNDERTAKING. CURTESY OF DNV THIS SLIDES GIVES AN IDEA OF THE LOGISTAICAL TASK TO CARRY OUT A 100% SURVEY OF A VLCC. A CONSIDERABLE TASK! LUCKILY 100% SURVEY IS NOT NECESSARY. EFFECTIVE AND MEANINGFUL SURVEYS MUST BE DIRECTED TOWARDS AREAS WHERE IT IS NEEDED AS IDENTIFIED IN EARLIER SLIDES. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Wing cargo tank on a small single hull VLCC (Source DNV)
Note the surveyor in the tank bottom Volume of tank abt cubic meter Notice no access – no railings on stringers TO GIVE AN IMPRESSION OF THE PHYSICAL SIZE A SURVEYOR CAN BE SEEN STANDING IN THE CARGO TANK AS INDICATED WITH AN ARROW. THERE IS NO ACCESS TO THE STRUCTURE AS CAN BE SEEN. EVEN THE TANK BOTTOM IS DIFFICULT TO ACCESS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Probability of crack detection (source: DNV)
THE PROBABILITY OF DETECTING CRACKS IS SMALL UNTIL THE CRACK REALLY GETS BIG AS SHOWN ON THE DIAGRAM, COURTESY OF DNV. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Cargo tank top/bottom coating
AS INDICATED IN RED IT IS POSSIBLE TO APPLY A SUITABLE COATING TO THE TOP OF THE CARGO TANKS AND THE INNER BOTTOM AS A CORROSION PREVENTION MEASURE. ALTHOUGH THE LIGHT COLOUR COATING WILL CHANGE WHEN EXPOSED TO INERTGAS AND CRUDE OIL IT WILL STILL BE EASIER TO SEE ANY COATING DETERIORATION AND THE ONSET OF LOCALIZED CORROSION COMPARED TO UNCOATED AREAS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

MEASURING METHOD Hull plate thickness can be measured with the ship afloat. A vehicle with special instrumentation will crawl along the bottom MEASUREMENT METHODS HAVE ADVANCED SOMEWHAT DURING RECENT YEARS. ONE DEVELOPMENT IS A VEHICLE THAT CAN CRAWL ALONG THE BOTTOM OF THE VESSEL, SEND SIGNALS INTO THE HULL BOTTOM PLATE AND INTERPRETE THE ECCOS IT RECIEVES. A COLORED DIAGRAM SHOWING THE THICKNESS MEASUREMENT RESULTIS THEN PRODUCED. INTERTANKO UK Corrosion 2002 Cardiff October 2002

THICKNESS MEASUREMENT SHIPS BOTTOM PLATING
THE COLOR DIAGRAM SHOWS THE IN-WATER BOTTOM PLATING THICKNESS MEASUREMENT RESULT. THE RED AREA NEEDS ATTENTION. THE YELLOW NEEDS WATCHING. THIS IS AN EXAMPLE OF THE RESULT FROM MEASURING THE BOTTOM PLATE THICKNESS ON A SHIP AFLOAT. THE RED AREA NEEDS ATTENTION. THE YELLOW AREA NEEDS WATCHING. THE BLUE IS FINE. INTERTANKO UK Corrosion 2002 Cardiff October 2002

Building blocks BLOCK SIZE IS IMPORTANT TO REDUCE THE AMOUNT OF PAINT REPAIRS – WHEN THE BALLAST CARGO TANKS ARE COATED AT THE BLOCK STAGE. BLOCK WELDS - EXTERNAL A SHIP IS NORMALLY PRODUCED BY PUTTING TOGETHER SMALLER BUILDING BLOCKS IN THE BUILDING DOCK. THE LARGER THE BLOCKS ARE THE LESS WELDING THERE WILL BE IN THE BUILDING DOCK. THE LESS WELDING THERE IS THE LESS COATING REPAIRS THERE IS IN THE BUILDING DOCK AND CONSEQUENTLY LESS CAHNCES FOR COATING DEFECTS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

THENAMARIS - New Suez max tanker during construction 2000
LAST SECTION OF MAINDECK WILL CLOSE THE DECK NOTICE THE BULKHEAD PLATFORM A NEWBUILDING IN THE FINAL MOMENT BEFORE THE DECK IS CLOSED. IT MAY BE POSSIBLE TO SEE THAT THE STRINGERS HAVE BEEN MODIFIED AS PLATFORMS AND RAILING TO PROVIDE ACCESS BY USING EXISTING STRUCTURES THAT MUST BE THERE ANYWAY. INTERTANKO UK Corrosion 2002 Cardiff October 2002

THENAMARIS – ATHENS MEANS OF ACCESS
WALKWAY FOR INSPECTION IN BALLAST TANK LOOKING CLOSER AT THIS TANKER IT IS POSSIBLE TO SEE THE WALKWAY ARRANGEMENT IN THE BALLAST TANKS. NOTICE THE LADDERS THROUGH STRINGER DECKS WITH RAILING SUITABLE AS INSPECTION PLATFORMS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

THENAMARIS – ATHENS Walkway in ballast tank using oversized longitudinal fitted with railing BALLAST TANK WALKWAY ARRANGED BY ENLARGING LONGITUDINAL. NOTICE THE RAILING FOR SAFETY OF PERSONNEL. INTERTANKO UK Corrosion 2002 Cardiff October 2002

THENAMARIS – ATHENS Coated cargo tank inner bottom to prevent MIC corrosion COATING APPLICATION ON CARGO TANK INNER BOTTOM TO PREVENT MIC PITTING. INTERTANKO UK Corrosion 2002 Cardiff October 2002

THENAMARIS/ ATHENS Coating of tank head – ullage space
Dark area – coated to prevent ullage space corrosion NOTICE THAT THE UNDER DECK AREA OR TANK HEAD OF THE CARGO TANK IS COATED AS WELL AS ABOUT ONE METER DOWN. NOTICE THE ENLARGED STRINGER THAT IS USED AS WALKWAY FOR INSPECTION. IT IS VERY NICE AND A MAJOR STEP IN MAKING TANKER STRUCTURES ACCESSABLE FOR PHYSICAL, VISUAL AND CLOSE UP INSPECTION. Note access platform with railing for inspection coated INTERTANKO UK Corrosion 2002 Cardiff October 2002

THENAMARIS - ATHENS CARGO TANK HEAD INSPECTION ACCESS PLATFORM
COATED CARGO TANK TOP (DARK AREA) ACCESS LIKE THIS WILL MAKE CLOSE UP VISUAL INSPECTION OF TANKER STRUCTURES MUCH EASIER AND SAFER. CHANCES FOR CORROSION GOING UNDETECTED IS ALMOST ELIMINATED. INTERTANKO UK Corrosion 2002 Cardiff October 2002

VLCC cargo tank walkway
Oversized longitudinals HERE WE SEE A DOUBLE HULL VLCC MIDSHIP SECTION CENTRE TANK. NOTICE THE OVERSIZED LONGITUDINALS AND THE PLATFORMS AROUND THE WEB FRAMES TO GIVE RELATIVELY EASY ACCESS FOR INSPECTION OF STRUCTURES. Notice oversized longitudinals as access walkway for inspection and the walk way platforms around the web frames INTERTANKO UK Corrosion 2002 Cardiff October 2002

CONCLUSIONS (1/5) CORROSION CAN BE DUBBED MANY NAMES – BUT NAME CHANGE IS NO SUBSTITUTE FOR INSPECTION, DISCOVERY AND REPAIRS. CORROSION RISK CAN BE PREDICTED, LOCATION IDENTIFIED AT DESIGN STAGE, PERMANENT ACCESS ARRANGED FOR MONITORING IN SERVICE. CORROSION, CRACKS AND BUCKLING CAN BE DISCOVERED – ACCESS FOR CLOSE-UP INSPECTION IS NEEDED. IT IS TIME TO DRAW SOME OBVIOUS CONCLUSIONS. CORROSION CAN BE GIVEN MANY NAMES, BUT CORROSION CAN BE PREDICTED, HIGH RISK LOCATION IDENTIFIED. CORROSION CAN BE DISCOVERED IN SERVICE. THENAMARIS HAS GIVEN LEAD TO THE INDUSTRY AND SHOWN HOW ACCESS CAN BE DESIGNED INTO THE STRUCTURES. INTERTANKO UK Corrosion 2002 Cardiff October 2002

CONCLUSION (2/5) MODIFY LONGITUDINALS ON NEW SHIPS TO BE USED AS ACCESS PLATFORMS. OWNERS MUST DEMAND THAT – CLASS MAKE PERMANENT ACCESS REQUIREMENT COMPULSORY AND HARMONIZED FOR ALL CLASS SOCIETIES. COATING MUST BE APPLIED TO CARGO TANK TOP & INNER BOTTOM AS COMPULSORY IACS COUNTERMEASURE AGAINST CORROSION. MODIFY EXISTING CONSTRUCTION DETAILS LIKE LONGITUDINALS AS ACEESS PLATFORMS. OWNERS MUST DEMAND PERMANENT ACESS ARRANGEMENT IS MANDATORY. CORROSION PREVENTING COATING MUST BE COMPULORY – TOP AND BOTTOM. INTERTANKO UK Corrosion 2002 Cardiff October 2002

CONCLUSION (3/5) NEGATIVE TOLERANCE ON STEEL PLATE THICKNESS MUST STOP – POSITIVE TOLERANCE ONLY ACCEPTABLE. SHIPBUILDERS MUST EXTEND HULL STRUCTURE AND COATING GUARANTEE FROM ONE TO FIVE CALENDAR YEARS TO MATCH THE FIRST SPECIAL SURVEY. GUARANTEE LENGTH IS A SAFETY MATTER – NOT A COMMERCIAL ISSUE. CLASS ACEPTANCE OF NEGATIVE STEEL PLATE THICKNESS MUST BE ABOLISHED. SHIP BUILDERS GUARANTEE FOR ALL TANK COATINGS AND HULL STRUCTURES MUST EXTEND TO THE FIRST SPECIAL SURVEY WHEN THE SHIP IS 5 YEARS OLD. THE GUARANTEE PERIODE FOR COATINGS AND HULL STRUCTURES IS A SAFETY MATTER – NOT A COMMERSIAL ISSUE. INTERTANKO UK Corrosion 2002 Cardiff October 2002

CONCLUSIONS (4/5) SHIP REPAIRERS MUST REPAIR SHIPS IN A RESPONSIBLE AND PROFESSIONAL MANNER – SHIP REPAIRERS SHOULD BE HELD LIABLE FOR INADEQUATE REPAIRS. OWNERS, CLASS AND THE INDUSTRY HAVE COMMON INTEREST IN NEVER AGAIN SEEING A TANKER OR ANY SHIP GOING DOWN AND SPILL HER CARGO BECAUSE OF CORROSION AND LESS THAN SATISFACTORY REPAIRS. SHIP REPAIRERS ARE PART OF THE RESPONSIBILITY CHAIN AND ARE UNDOUBTEDLY RESPONSIBLE FOR A NUMBER OF LESS THAN SATISFACTORY REPAIRS. INTERTANKO UK Corrosion 2002 Cardiff October 2002

CONCLUSIONS (5/5) ALL CLASS SOCIETIES’ GOVERNING BODIES HAVE SIGNIFICANT NUMBERS OF SENIOR EXECUTIVES FROM SHIP OWNING, SHIP OPERATING INTERESTS. THESE SENIOR EXECUTIVES HAVE A PARTICULAR DUTY TO TAKE THE LEAD, BE PROACTIVE AND ENSURE CLASS/IACS SPEED UP THE PROCESS OF; UNIFORM SCANTLING REQUIREMENTS UNIFORM FATIGUE CALCULATIONS GENERAL HARMONISATION OF CLASS RULES INSPECTION ACCESS AND COATING FOR CARGO TANKS A DOUBLE HULL TANKER SUFFERING THE SAME FATE AS THE SINGLE HULL ERIKA OR CASTOR COULD HAPPEN IN FUTURE YEARS. IT DOES NOT HAVE TO HAPPEN IN BAD WEATHER BECAUSE OF HULL STRUCTURES WEAKENED BY UNDISCOVERED CORROSION. THE OIL PRODUCERS KNOW VERY WELL WHAT THE CRUDE OILS CONTAIN – THE OIL PRODUCERS MUST INFORM TANKER BUILDERS AND OWNERS. WE KNOW VERY WELL HOW THE CORROSION MECHANISMS WORK. WE KNOW HOW TO CONTROL IT. EXAMPLES HAVE BEEN SHOWN ABOUT COATING AND HOW ACCESS CAN BE MADE BY APPLYING A BIT OF INGINUITY TO EXISTING STRUCTURES – LIKE THENAMARIS OF ATHENS, GREECE HAS VERY CLEVERLY DONE. LOOKING THROUGH THE CLASS SOCIETIES GOVERNING BODIES NAME LISTS IT IS CLEAR THAT THE SHIP OWNING INTERESTS ARE WELL REPRESENTED THERE BY SENIOR EXECUTIVES FROM SHIP OWNING/MANAGEMENT COMPANIES. THOSE REPRESENTATIVES HAVE A PARTICULAR DUTY TO BE PROACTIVE, DYNAMIC AND ENSURE THAT THE CLASS SOCIETIES PLUG THE LOOPHOLES IN THE REGULATIONS BY SPEEDING UP THE PROCESS OF; UNIFORM SCANTLING UNIFORM FATIGUE CALCULATIONS GENERAL HARMONIZATION OF CLASS RULES INTRODUCING MEASURES TO MANAGE CARGO TANK CORROSION – ACCESS – COATING APPLICATION IN TOP AND BOTTOM. NOTHING NEW – NOTHING REVOLUTIONARY – NOTHING IMPOSSIBLE QUITE SIMPLE - REALLY!! THANK YOU FOR YOUR ATTENTION! INTERTANKO UK Corrosion 2002 Cardiff October 2002

INTERTANKO UK Corrosion 2002 – Cardiff, Wales October 24, 2002

Similar presentations

Presentation on theme: "INTERTANKO UK Corrosion 2002 – Cardiff, Wales October 24, 2002"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

INTERTANKO UK Corrosion 2002 – Cardiff, Wales October 24, 2002

Similar presentations

Presentation on theme: "INTERTANKO UK Corrosion 2002 – Cardiff, Wales October 24, 2002"— Presentation transcript:

Similar presentations

About project

Feedback