Ameron International Corp. on Tuesday said that its board agreed to sell the industrial pipe maker to the nation’s largest oilfield equipment maker for $772 million.

Houston-based National Oilwell Varco Inc. will pay Ameron shareholders $85 cash per share, a 28 percent premium to the stock’s closing price on Friday. If approved by Ameron shareholders, the deal is expected to close in the fourth quarter.

Ameron makes fiberglass-composite pipe for transporting oil, chemicals and corrosive fluids and has customers on several continents, National Oilwell executives said they were especially interested in the company’s offshore drilling products.

“Ameron’s marine and offshore products will expand National Oilwell’s offering into seawater-handling systems in new oil and gas drilling and floating production, storage and offloading vessels,” Chief Executive Pete Miller said in a statement.

Miller said that he had discussed a merger in the past with Ameron Chief Executive James Marlen, but that the right circumstances had not presented themselves until now. Marlen said National Oilwell has the resources to grow the company.

“The Ameron businesses, while confronting a challenging business environment at this time, hold strong positions, and we have structured the businesses to capitalize on growth opportunities as markets recover,” Marlen said in a statement.

The deal comes months after activist hedge fund Barington Capital Group L.P. won a seat on the board following a contentious proxy battle. Barington Chief Executive James Mitarotonda argued that the company was undervalued and Marlen had a poor track record in creating shareholder value.

Ameron shares were up $18.23, or nearly 28 percent, to $84.50 in midday trading on the New York Stock Exchange.