At the time of filming in 1974, this plant had been manufacturing steel nonstop for 102 years using the Bessemer process. [Sir Henry Bessemer]’s method for turning pig iron into steel was a ...

Among the things he did, he incorporated the Bessemer process in his steel manufacturing factories; he standardized workplace procedures to attain greater efficiency; he opted for vertical integration ...

so there was a demand for steel called low background steel, which was made before the trinity tests. The Bessemer process pumps air through the iron to remove impurities. shropshirehistory.com ...