US oilfield equipment group National Oilwell Varco (NOV) is buying oil pipeline supplier NKT Flexibles from Danish industrial group NKT Holding and Norway's Subsea 7, for 3.8 billion Danish crowns ($673.4 million).

NKT Holding owns 51 per cent of NKT Flexibles, while Subsea 7 owns the remaining 49 per cent.

Kalundborg, Denmark-based NKT Flexibles is a supplier of flexible pipelines for the offshore and chemical industries. It manufactures dynamic and static risers, static flowlines, subsea jumpers, topside jumpers and expansion joints.

Flexible pipes are used for offshore oil and gas applications including production, gas lift, gas injection, water injection and various ancillary lines including potable water and liquid chemical lines.

Its flexible pipe systems are used by nearly all the oil and gas companies to extract oil from offshore as well as coastal shallow waters to ultra-deep waters all around the world.

Last year NKT Flexibles was awarded a $1.8 billion to supply flexible pipes to Brazilian oil giant Petrobras. It is now building a dedicated flexibles fabrication plant in Brazil, which will be ready for commercial operation in 2013.

NKT Flexibles had 2011 revenues of 1.5 billion crowns and pro forma earnings before interest, tax, depreciation and amortisation (EBITDA) of 301 million crowns.

Houston-based National Oilwell Varco designs, manufactures and sells equipment and components used in oil and gas drilling and production operations.

Pete Miller, chairman, president and CEO of NOV, said, "The incorporation of NKT's highly technical design capability and business into our Rig Technology group is an exciting and strategic opportunity for NOV.''

''The addition of NKT's technology and expertise to our current suite of products for the offshore production market significantly increases our footprint in this growing segment of the oil and gas industry. We look forward to welcoming the employees of NKT into the NOV family," he added.