* Vessel towed from berth for repairs, shipments normalized
* Move opens port that moves about 10 pct of world iron ore
* Vale Beijing was receiving first cargo, on maiden voyage
(Updates to add Vale statement, comments)
By Jeb Blount and Sabrina Lorenzi
RIO DE JANEIRO, Dec 6 (Reuters) - The damaged Vale Beijing, the world's largest iron ore carrier, was towed on Tuesday from its berth in Brazil for repairs, clearing the way at a port responsible for about 10 percent of global iron ore exports.
Tugs moved the massive ship from the dock at the Ponta da Madeira port in northeastern Brazil to an area outside the shipping channel, allowing mining giant Vale (VALE5.SA) (VALE.N) to resume ore shipments, the company said in a statement.
The ship, delivered in September to its owner and operator, South Korea's STX Pan Ocean (028670.KS), is longer and wider than three soccer fields. It was about to start its first fully loaded voyage, a planned run to Rotterdam.
The Ponta da Madeira port outside the city of Sao Luis is operated by Vale, the world's second-largest mining company, which has a long-term contract with STX to ship iron ore, the main ingredient in steel. Vale said the interruption at the port stopped it from loading 750,000 tonnes of ore.
"Things like this have happened before but usually not with a ship so new," said Nelson Carlini, a naval engineer and president of Porto Assessoria Ltda, a Brazilian naval construction and port consulting group.
"We won't know for a while, but it could be a hidden construction or materials problem. I doubt it's from loading, Vale has a very good record of properly loading ships."
The Vale Beijing is one of the first of nearly three dozen "very large ore carriers," or "Valemax" vessels that the company has commissioned to be built in China and Korea to help cut the cost of shipping iron ore to China, the world's largest steelmaker, and to clients in Europe.
While Vale's iron ore quality is higher, its distance from China puts it at a disadvantage to producers such as BHP Billiton (BLT.L) and Rio Tinto (RIO.AX), whose main mines are located much closer in Australia. China has not yet granted Vale the right to dock its giant ships at Chinese ports, citing technical and potential environmental problems.
China and Brazil are trading partners but also commercial rivals. Beijing is concerned about its growing dependence on natural resources while Brasilia frets about the impact of Chinese manufactured goods on its own industries.
Still, it came as a surprise when the Vale Brasil, the first Valemax ship to load at Ponta da Madeira, had to turn around in the Indian Ocean on its maiden voyage in June after the Chinese government failed to provide permission for the giant ship to dock. It went to Italy instead. [ID:nL4E7N20ZO]
The Vale Beijing is loaded with 384,300 tonnes of high-grade ore, enough to make steel for nearly 3-1/2 Golden Gate Bridges. The ore was mined by Vale at its giant Carajas complex in Brazil's Amazon region and destined for Rotterdam.
CAUSE STILL UNKNOWN
While the big ships are also intended to help cut transport costs to Europe, Vale's second-largest market, the fleet is designed primarily for China.
If blocked from China, it may be forced to send more ore to its planned Malaysian iron-ore stockpiling and distribution center, which is still under construction.
"Vale's expansion is behind schedule and the Malaysian depot won't open until 2014," said Janet Lewis, analyst with Macquarie Securities. "I don't think steelmakers are so much against the ships as the shipping companies, and if China shuns, they will be used mainly for the Malaysia depot."
Carajas is one of the world's largest sources of iron ore with more than 60 percent iron content and is connected to Ponta da Madeira by a railway that snakes nearly 900 km (560 miles) through the Amazon jungle, more than twice the distance between Washington and New York.
A crack in the Vale Beijing's ballast tanks was either the result of loading its holds or a structural problem, an official with the Sao Luis harbor pilots' service told Reuters.
The official, who asked not to be identified, said the Vale Beijing could not use its own motors during the move from the dock for fear of causing further damage.
Because there are no facilities to unload iron ore at Ponta da Madeira and no large shipyards in the area, repairs must be made by divers while the ship is at anchor, the harbor pilots' office said.
"Repairs like this are totally possible and can be done both inside and outside the ship on a temporary basis," Carlini, the naval engineer, said.
Harbor pilots have detailed knowledge of the harbors where they live and work and are required by law and marine tradition to go aboard all large vessels arriving or leaving a port to steer them through approved channels and clear of marine obstacles and other ships.
Their work is closely regulated by world navies and coast guards and their dispatch offices track marine traffic and activity for the entire ports and harbors. (Additional reporting by Jonathan Saul in London; Editing by Todd Benson, Marguerita Choy and David Gregorio)