PITTSBURGH | United States Steel Corp., the largest U.S.-based steel maker, and other producers of steel pipe used in oil and gas drilling on Wednesday filed complaints with U.S. trade officials over alleged unfair competition from Chinese imports they say have flooded the domestic market.

Steel makers have faced sharply lower demand since late last year, when the global economic crisis undercut key customers in the construction, automotive and heavy equipment industries. The decline comes just months after surging orders from China and other countries helped fuel record profits for many U.S. steel companies.

Several companies and the United Steelworkers union filed petitions with the Commerce Department and the U.S. International Trade Commission seeking new tariffs on imports of the so-called oil country tubular goods, according to their Washington, D.C.-based attorney, Roger Schagrin.

"Just huge quantities of the Chinese imports over the last nine months have gone into inventories on the ground in the United States," he said.

The other included in the complaint are Evraz Rocky Mountain Steel of Pueblo, Colo.; TMK IPSCO of Downers Grove; V&M Star and V&M TCA, both of Houston, and Wheatland Tube Corp. of Beachwood, Ohio.

The industry making tubular pipe employs about 6,000 workers, and about 2,000 of them have been laid off, United Steelworkers International President Leo W. Gerard said in a statement.