Nippon Steel Corp., the world's second-biggest maker of the metal, raised prices of plate to Hyundai Heavy Industries Co. by about 50 percent to a record as costs surged, according to two people familiar with the matter.
The steelmaker and Hyundai, the world's biggest shipyard, agreed to a price between 145,000 ($1,330) and 150,000 yen a metric ton starting next month, according to a person involved in the talks. Daewoo Shipbuilding & Marine Engineering Co., the world's third-largest shipyard, also approved the gain, he said.
Nippon Steel and rival mills need to raise product prices to make up for a surge of as much as 97 percent in iron ore this fiscal year and a tripling in coking coal. Korean and Chinese shipyards are buying more of the alloy as they fill order backlogs stretching into 2012.
''We can't comment on price negotiations with individual customers,'' said Hayato Uchida, a spokesman for Nippon Steel.
The Japanese mill had been selling plate to Hyundai and Daewoo at between 90,000 yen a ton and 100,000 yen from April through this month.
''We reached a general agreement with Nippon Steel on steel plate talks,'' said Kim Kwang Kook, a spokesman at Hyundai Heavy. The company was still in talks to finalize details and expected to reach a final agreement next week, he said.
Daewoo Shipbuilding said in an e-mailed response that it was still in talks.
Nippon Steel in July said it raised prices for plate sold through wholesalers in Japan on an immediate-delivery basis by 10,000 yen a ton starting Aug. 1. The increase brought the jump in domestic prices to 50 percent since the quarter ended March, when the company's average product price was 80,200 yen a ton.