SYDNEY, March 31 (Reuters) - Energy infrastructure owner Duet Group DUE.AX launched a A$200 million ($153 million) capital raising on Thursday to finance the purchase of the remaining 20 percent of the Western Australian state gas transmission line it does not already own from Alcoa (NYSE:AA) Inc's AA.N Australian arm.
Trading in Duet shares were suspended after the company launched the raising to pay Alcoa A$205 million for its stake in the 950 mile (1,500 km) Dampier-Bunbury pipeline (DBP).
Duet's fully underwritten placement will be offered to institutional investors at A$2.20 a share, a 3.5 percent discount to the stock's Wednesday closing price of A$2.28.
Alcoa of Australia, 60 percent owned by Alcoa and 40 percent by Alumina Ltd AWC.AX , said it expected a net cash impact of about $115 million from the transaction.
The biggest pipeline customer, it planned to keep its access to roughly 30 percent of the pipeline's transmission capacity for gas supply to its three alumina refineries.
Alcoa was the initial cornerstone customer of the pipeline after partnering with the state government in the early 1980s to underwrite its construction. At the time it was the state's largest infrastructure project and helped helped facilitate the development of Australia's North West Shelf liquefied natural gas project.
The sale is expected to close in April. ($1 = 1.3050 Australian dollars)