The U.S. Commerce Department has reassessed its anti-dumping margins on so-called oil country tubular goods (OCTGs) exported by South Korean steelmakers, industry sources said Wednesday.

According to the sources, the Commerce Department lowered the anti-dumping margin on Nexteel Co.'s OCGTs to 3.63 percent from the previous 29.76 percent.

SeAh Steel Corp. saw the dumping margin placed on it rise to 3.31 percent from the 2.76 percent levied earlier.

In its previous reviews, Washington maintained higher anti-dumping margins on OCTGs made by South Korean steelmakers.

OCTG is one of the fastest growing sectors in the pipelines market, and South Korean producers enjoyed a boom in the North American country's oil and gas industry.

Local mills exported $818 million worth of OCTGs to the world's largest economy in 2013, but the amount shrank drastically to $262 million in 2015 and $271 million in 2016.