It was in a warm and humid November day of 2006, that Jo Clipper, a 25 year old chemical tanker transited Singapore on her way to a remote ship yard in China. Technical Superintendent Egil Hansen of Executive ship management, the manager of the vessel, boarded her as the lady was to have a thorough make over- from a single hull to double hull in addition to clearing her CAP-! Survey. A challenging job indeed, for which the preparation started as early as the summer of 2006 led by the project team headed by Mr. Jan Enga from Jo Tankers.
The aim was not only to give a conversion from single hull to double hull for the lady but also to prepare her for the CAP-1 rating as the business demands. We have here a report sent by Egil from the yard.
Meticulous planning and preparation, that’s the way a job of such magnitude could be handled. The project team put the ball rolling by starting the block production months in advance so that the stage one blocks were finished when the vessel arrived in the yard by first week of December. At the same time, the project team appointed two steel inspectors in the team just to ensure the quality of the production from day one.
In addition to conversion to double hull, the vessel also had to renew some 640mts of bulb plates (55 ton) in vessel's DB tanks to satisfy the CAP survey requirements. Additionally, bulkhead between FPT and DT was remaining to be done and some stringer plates in DBT. This was because the vessel was aiming for CAP-1 overall steel rating after the Conversion was over.
As another smart move- the vessel also picked up the Bulb plates while passing Singapore, which were earlier left in Sembawang storage, Singapore during the last dry-docking in 2005. Indeed a big save on custom cost and time but importantly, these Bulb plates are difficult to get in China!
Planning for leading a thoroughly clean ship to the dock was another challenge for the crew since the vessel carried Veg oil in all Wing tanks from Pasir Gudang (Malaysia) to be discharged in Zhangjiagang, a nearby port. In order to save time and cost, Fwd Heavy Fuel Oil tanks also had to be emptied and washed clean for hot work before arriving the yard. Thanks to a spirited team of crew on board, this was all completed in seven days, before arriving at the Nantong Pilot station, so the vessel could be declared gas free and ready for the yard on arrival Nantong COSCO Anchorage.
Bunkers needed careful planning for the vessel in order to safely reach the first Load port (Singapore / Japan / Korea) from Nantong after the conversion since price for bunkers is high in China. Moreover there was no place to store bunkers during conversion period when tanks were required empty and gas free for Hot work.
Maximum depth along repair terminal was 6.5 meter in Yangse River with strong current in and out. About 7800 ton of FW was filled in the Center cargo tanks to reduce overall seagoing stress to about 50% for the fitting of the conversion steel. There was no need for dry docking the vessel since no docking job was pending as such. All steel to be inserted via the wing Cargo tanks.
COSCO Nantong Yard have 2 floating docks and three alongside berths. All of them are occupied at most of the time. Double / Multiple banking up to 4 vessels is normal. Reach for Shore Crane is essential when handling steel so all steel (blocks) had to be handled in one go to the vessel when vessel was on double banking position 2 at berth No. 2. Vessel needed hydraulic power on her winches (for attending moorings) and cargo pumps (for adjusting ballast) until all steel were landed onboard.
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The idea was to cut the vessel's main deck al along from the break of forecastle till the break of Accommodation and insert the new bulkhead blocks and weld them in place. Thereafter close the deck plating, pressure test the cargo tanks, cut open the tank tops of ballast wing tanks into the DB tanks to make them continuous tanks. This sounds to be very simple but in practice was quite a big job. The ladders in Cargo tanks were to be adjusted, new access / ladders and platforms to be made in the new (extended!!!) Ballast tanks, relocation of Sounding Pipes, ullage ports, Tank cleaning Butterworth Hatches, Radar Gauges, Ballast tank air vents etc.,
To maintain the integrity of the vessel, the plan to fit the blocks was split into two stages. The deck was divided into different sections. During the first stage, the deck plate was opened at alternate sections and the blocks inserted. After fitting them in place and doing about 50% welding the deck access was to be closed and the second stage was to be started by cutting the deck access for the remaining sections.
Vessel went in dry-dock anyway on yard's cost. There was so much blasting of steel going on alongside the first double banked vessel that the yard decided to use an empty period of Yantong Floating Dock and then dry docked the vessel for the steel blocks fitting up process. The vessel was given the cooling water by the yard so that she can run her own AE for the power needed.
When all deck openings are closed and all blocks in stage one is welded 100%, then vessel is expected to be undocked and berthed as in No. 1or 2 position in any of the available three berths for sand blasting. She will remain in this position until all tanks are blasted and then move to 2nd and 3rd positions for painting and other remaining Jobs until her departure.
With the mercury tipping down to 2 deg C, even for a Norwegian the winter weather in China is cold. Much fog / dust and wind in the area. We also experienced heavy rains.
Dust in tank areas
After gauging / grinding of paint and welding in tanks the air becomes filled with all sorts of particles. Special mask was handed out to the ship’s crew and officers. Enclosed picture shows the filter from one of the masks used for a day’s inspection about 3-4 hrs in a tank. All crew members gladly made use of the PPE under these circumstances.
Helmets, goggles and gloves
Staging building (Scaffolding) in China cannot be compared to other area in the world. Every day reports about loose planks, sharp scrap metal on the staging were given to safety in the yard. However, strict vigilance was maintained so that no safety rule was by passed at any stage.
The conversion project is still underway till Jo Clipper will come out with her complete make over by mid February, 2007. Till then, it’s been a great teamwork of the project team, managers, appointed outside inspectors and the shipyard. In fact, all Steel Inspectors and visitors were very pleased with vessel’s warm hospitality during yard stay. By limiting the space for yard workers in accommodation, the ships staff managed to keep good food and nice quarter for hungry visitors. When people are climbing up and down - about 500-600 ladder steps per day in narrow dusty tank spaces, they appreciate the good hospitality onboard. A big laud of applause for the team on board Jo Clipper!
- by Egil Hanssen. |
