KNOXVILLE, TENN. (Feb. 1, 1:15 p.m. ET) -- A Chicago-based investment firm has acquired high density polyethylene pipe and conduit producer Dura-Line Holdings, formerly known as A-D Technologies, effective Jan. 31.

Dura-Line of Knoxville, Tenn., complements CHS Capital’s stakes in markets served by other CHS portfolio companies.

“CHS Capital has impressive experience in building and growing global businesses,” stated Dura-Line President and CEO Paresh Chari in a Jan. 31 news release. “Furthermore, their expertise with other investments in the energy and water infrastructure sectors will be beneficial to us as we expand into new markets and geographies.”

Dura-Line runs eight U.S. plants making HDPE conduit, duct and pressure pipe for telecom, data communications, energy and infrastructure markets. As A-D Technologies it reported 2010 extrusion-related sales in North America of $247 million in Plastics News’ pipe, profile and tubing survey. It also said it employed 700 and operated 88 production lines in North America. For 2010 it reported total sales, including those for offshore operations, at $354 million.

On Feb. 2 officials said in an e-mail that Dura-Line’s global annual sales now exceed $400 million and global employment is more than 1,200. They did not disclose terms of the CHS acquisition of Dura-Line.

“Dura-Line is the clear industry leader with unmatched capabilities and capacity and significant exposure to high-growth emerging markets,” noted CHS partner Dan Hennessy in a news release.

CHS’s industrial, infrastructure & energy portfolio includes global provider of heat tracing and thermal control products firm Thermon Group Holdings Inc., global designer and producer of geosynthetic linings GSE Holding Inc., and LVI Services Inc., the biggest U.S. remediation and facilities management company. CHS also has stakes in several companies that supply plastic products for other markets, including housewares, picture frames, expanded polystyrene foam, injection molding, cutlery, wire and cable, underground infrastructure and rigid containers and closures.

CHS is a private equity firm investing in the middle market. Its investment in Dura-Line is a partnership between CHS, GSO Capital Partners LP and Dura-Line’s senior management team. CHS has raised $2.9 billion of capital over 24 years in the middle market.

A-D Technologies expanded about a year ago when it bought BoreFlex Industries Inc. of Mountain Grove, Mo. Dura-Line’s U.S. plants are in Elyria, Ohio; Mountain Grove, Mo.; Graniteville, S.C.; North Salt Lake City, Utah; McAlester, Okla.; Sandersville, Ga., Middlesboro, Ky.; and Sparks, Nev.

Dura-Line also runs two plants in Mexico, one in the Czech Republic, three in India and one in Oman.

A-D Technologies changed its name to Dura-Line on Jan. 31 to capitalize on the high profile of the Dura-Line brand. CHS bought Dura-Line from Boston equity company Audax Group on the same day.