* Ratos and AP 6 fund buy 50 pct stake
* Norway's Ferd to hold remaining shares
* Deal values Aibel at $1.5 bln
* Deal seen completed in Q1, 2013
STOCKHOLM, Dec 18 (Reuters) - Private equity group Ratos and a Swedish pension fund said on Tuesday they would jointly buy a 50 percent in stake in Norwegian oil services group Aibel in a deal valuing the company at 8.6 billion crowns ($1.53 billion).
The deal would see Norwegian industrial and financial group Ferd, which at present directly and through a private equity fund owns 80 percent of Aibel, hold a 50 percent stake in the services group.
Aibel has about 8,000 employees and provides services within the oil, gas and renewable energy sectors, with major oil companies operating on the Norwegian continental shelf as its main customers, Ratos said in a statement.
"Aibel operates in a market with strong growth, has long-term customer relationships, a unique business model, a strong order book and a dedicated management team, which makes this a very attractive investment for Ratos," Ratos Chief Executive Susanna Campbell said in a statement.
Under the terms of the deal, Ratos will own 32 percent, the Sixth AP Fund 18 percent and Ferd the remainder. Ratos and the Sixth AP Fund will invest via a jointly owned company which will be represented by Ratos on Aibel's board, Ratos said.
Aibel is expected to generate sales of more than 10 billion Norwegian crowns this year with an operating margin (EBITDA) of about 9 percent, Ratos said.
The deal is subject to approval from the relevant regulatory authorities and is expected to be completed during the first quarter of 2013. (Reporting by Niklas Pollard)