The European Union imposed tariffs as high as 61.4 percent on aluminum radiators from China to help Italian and Polish producers compete with cheaper imports.

The duties punish Chinese exporters such as Zhejiang Guangying Machinery Co. for selling the radiators in the EU below cost, a practice known as dumping.

European manufacturers including Italy’s Fondital SpA and Poland’s Armatura Krakow SA have suffered “material injury” as a result of dumped imports from China, the European Commission, the 27-nation EU’s trade authority in Brussels, said today in the Official Journal. The levies, due to take effect tomorrow, are for six months and may be prolonged for five years.

Chinese exporters expanded their combined share of the EU market for aluminum radiators to 24 percent in the 12 months through June 2011 from 13 percent in 2008, according to the commission.

The duties are the preliminary outcome of an inquiry that the commission opened last August after a dumping complaint against China by an industry group on behalf of producers that account for more than 25 percent of the EU’s output of aluminum radiators. The levies range from 12.6 percent to 61.4 percent, depending on the Chinese company. Zhejiang Guangying Machinery faces a 21.2 percent levy.

EU governments, acting on a proposal from the commission, must decide within six months whether to turn the provisional anti-dumping duties into “definitive” levies lasting for five years. The rates of any definitive duties can change.