Oil services group Petrofac has a new chairman after buying the services of venture capitalist and chairman of Cairn Energy Norman Murray.The 62-year-old, a co-founder and former chairman of Morgan Grenfell Private Equity, will replace Rodney Chase following six years in the role after the AGM on 13 May.It won't affect his work as a non-executive director of pub owner and brewer Greene King and at dairy group Robert Wiseman Dairies.At the same time, Roxanne Decyk, 58, will take over as a non-executive director following Kjell Almskog's departure.Decyk spent 11 years at Royal Dutch Shell, most recently as head of the government affairs department."After six enjoyable years as chairman of the board I feel it is the right time to be stepping down and I wish Norman well," said Chase. "I have no doubt that both Norman and Roxanne will each make a strong individual contribution to the board