US industry is concerned about subsidised Chinese imports
The $1.4bn US steel pipe-making industry has been "injured" by subsidised imports from China, a US commission has concluded.
The US International Trade Commission said the Chinese products had been sold at "less than fair value".
As a result, the Department of Commerce will impose duty of up to 700% on the imported goods.
This is the first time a US industry has successfully won protection from subsidised Chinese products.
Until last year, the US government refused to consider complaints from industry about the dumping of Chinese products as it did not classify China as a market economy.
The policy was changed in the face of growing anger from industrial producers who claimed they could not compete with much cheaper imports from China.
The tariffs on the imports of steel pipe will range from 99% to 701%.
The circular steel pipe affected by this judgement is used for home plumbing and sprinkler systems.
It is made by 21 producers in the US employing almost 2,500 people.