Tata Steel UK will begin shutting down operations at its Port Talbot-based coke ovens from Wednesday, impacting about 200 staff, the company has announced.
The steel group said it had been forced to make the closures earlier than previously planned because they can no longer be run safely.
Coke ovens are used to turn coal into coke, a key raw material which is used in the process of making steel.
Tata has about 40 remaining coke ovens, with many having already been shut down since they started running in 1981.
Tata confirmed in January that it will close blast furnaces at its plant in Port Talbot, South Wales, which is expected to result in the loss of more than 3,000 jobs.
Under the plans, its two high-emission blast furnaces will be closed, along with the coke ovens where closures were due to begin from July.
But Tata said it had been forced to cease operations earlier due to “significantly deteriorating operational stability”.
It means that about 200 workers employed at the Port Talbot coke ovens will be impacted. But it is understood that there will be no immediate redundancies and Tata is expecting to redeploy staff elsewhere in the business.
Once the ovens are shut, Tata will have to buy in all the coke it needs for the steelmaking process.
Rajesh Nair, Tata Steel UK’s chief executive, said: “The performance of the coke ovens has been deteriorating over many months, despite some herculean efforts by the teams there.
“The condition of the ovens has now worsened to a level making continued operation untenable.
“We will now begin the process of safely closing and purging the coke ovens, and ceasing operations at the adjoining by-products plant.”
The boss said he had “always been struck by the spirit and camaraderie of the workforce there who have always given everything to the plant, often in very difficult circumstances”.
He added: “We have been clear in our current restructuring proposals that many of our heavy-end assets in Port Talbot are at their end-of-life capability.
“As part of our efforts to stem our current losses, and given the condition of the assets, we propose to close the heavy end iron and steelmaking assets at Port Talbot within this calendar year in a phased manner.”
Tata said it is investing £1.25 billion into electric arc furnace technology at Port Talbot, which will secure steelmaking in the region for the long term and help transition to a lower-carbon process.
Alun Davies, the national officer for steel at steelworkers’ union Community, said: “The early closure of the coke ovens is a massive blow but we knew they have been deteriorating and our number one concern is the safety of our members.
“Tata know the unions will not accept any compulsory redundancies and we are working to conclude negotiations on an enhanced redundancy and retention package.”
Labour MP Jo Stevens, shadow Welsh secretary, said: “This is another difficult day for our Welsh steel industry due to understandable safety concerns.
“Those workers affected need assurances about their immediate future.
“A UK Labour government will invest in our steel industry to ensure the transition to green steel is fuelled by the skills, talent and ambition of Welsh steelworkers.”