Mr Siddall steps down from the board today and will formally leave the company he joined back in 2000 at the end of the month.
Mr Ling joined Amec in 1986 and is currently the firm’s group financial controller. The company said he will fill Mr Siddall’s role until a successor is found.
The news was made in an interim management statement on its prospects for 2008 which said the firm – which now concentrates on the oil and gas, power and process and environmental markets – was looking better than previous expectations.
It added: “Our end markets remain strong. We confidently expect to deliver the targeted six per cent margin.” It has a target margin of eight per cent by 2010.