WASHINGTON: The United States has set preliminary anti-dumping duties ranging from 36.53 percent to 99.14 percent on Chinese-made steel pipe used in oil wells, a source familiar with the decision said Thursday.

US companies imported $2.63 billion of "certain oil country tubular goods" from China in 2008, or more than three times the $750 million they imported in 2007.

That makes it the largest US trade action ever against China by volume of imports. It tops US President Barack Obama's decision in September to slap a 35-percent tariff on about $1.85 billion of Chinese-made tires.

The Commerce Department is expect to announce the preliminary duties later Thursday.

They reflect the department's determination of how far below "fair market value" Chinese companies are selling steel pipe and tubing product in the United States.

They are in addition to preliminary countervailing duties of 10.69 percent to 30.69 percent the Commerce Department announced in September to offset Chinese government subsidies to encourage production of the steel goods.

The decision comes shortly before Obama heads to Asia for a trip that includes stops in Shanghai and Beijing.

The Commerce Department decided one Chinese company targeted in the investigation, Jiangsu Changbao Steel Co., was not guilty of dumping in the United States, the source said.

However, that same company was hit last month with a 24.33 percent countervailing duty rate.

A group of US producers -- Maverick Tube Corp., United States Steel Corp, TMK IPSCO, V&M Star LP. Wheatland Tube Corp. and Evraz Rocky Mountain Steel -- asked the Commerce Department in April for the import protection.

They were joined by the United Steelworkers union, the driving force behind the tires case Obama decided last month.