Jon Stanton, the group’s finance director, has been named as chief executive designate and will succeed Cochrane from 1 October.
The firm, which makes valves and pumps for the energy and mining industries, said pre-tax profit fell to £82 million in the six months to the end of June, from £108m a year earlier.
Cochrane, who has been on the board for ten years and been chief executive since 2009, said: “Our first-half performance was ahead of market expectations and demonstrated the group’s fundamental strength and resilience. While markets remained challenging, the Minerals division fully captured available opportunities, Flow Control improved margins and Oil & Gas grew market share in important product categories.
“As a whole, the group continued to be highly cash generative and aggressively reduce costs, while also extending its technology leadership in products and services which are vital to our customers’ operations.”
The firm said an asset disposal programme of up £100m was “progressing to plan”, with £46m achieved to date.
Revenues for the period came in at £866m, down from £981m a year earlier.
On the forthcoming change at the top, chairman Charles Berry said: “Keith has demonstrated strong leadership over the last seven years and the substantial progress we have made during that time has been achieved through his passion, drive and determination.
“We are grateful for all he has done, and when he steps down, it will be with our very best wishes.
“Succession planning is a key task for the board and we have carefully considered the attributes we require in the new chief executive of the Weir Group. Having assessed external and internal candidates, we are delighted that Jon will step up to the role.”