A total of 63 jobs are to be axed at Crane Stockham Valve in the Castlereagh area of east Belfast.
Crane Stockham Valve has been operating in the Castlereagh area since 1955 and employs around 90 staff.
The US-owned business makes valves for energy and water markets.
Redundancies are expected to roll out from early next year.
George Brash from Unite says this announcement demonstrates a need for the Executive to focus on manufacturing here.
He said: “When it was last up-and-running, the Northern Ireland Executive refused to bring forward a strategy for the manufacturing sector. The absence of such a strategy – with real actions to defend jobs and skills – left Northern Ireland industry defenceless in a period of mounting challenge. This announcement reinforces the urgency of the newly re-established Executive to reconsider its approach and bring forward a Manufacturing Strategy for Northern Ireland.
“For its part, the company are citing global competition, market pricing pressure and financial performance in Belfast as justification for their decision but it seems likely that this is really about the race-to-the-bottom in production going to lower cost locations.
“Unite will be engaging with our shop stewards at the company and with our wider membership to identify our response to today’s announcement and next steps ahead”, Mr Brash concluded.