The United States has imposed preliminary duties ranging from 11 to 13 percent on steel pipe from China it said were unfairly subsidized, a source familiar with the decision said.

The decision is a victory for U.S. Steel Corp and the United Steelworkers union, which filed a petition in October asking for protection against the Chinese imports.

However, it puts further strain on U.S.-China trade relations, already tested by disputes over other U.S. trade actions and China's currency policy.

Texas company V&M Star LP and Illinois company TMK IPSCO also signed the petition asking for relief.

The Commerce Department is expected to announce its decision.

The case concerns seamless carbon and alloy pipe of 16 inches or less in outside diameter used in industrial piping systems to carry water, steam, petrochemicals, chemical, oil products, natural gas and other liquids and gasses.

The United States imported $382 million of the pipe from China in 2008, compared to $130 million in 2007.

U.S. petitioners have also asked the Commerce Department to impose anti-dumping duties in addition to the countervailing duties decided.

Anti-dumping duties are aimed at below-market prices and often are larger than countervailing duties. (Reuters)