When the second Cunarder, the Queen Elizabeth was ordered
from John Browns in 1936 this required 40,000 tons from the plate mills. Admirality
orders were also approaching and so proposals for expansion were prepared
at the instance of Dr Andrew McCance. Blast Furnace gas was piped from Clyde
Iron to Clydebridge in 1936 and the Q mixer furnace was installed (starting
operation in 1938). In 1942 the R furnace was added and in 1950 the S and
T tilting furnaces were added.
However, a series of drawings (B1756 versions 1 to 12) exist showing various proposals, originated in 1936 and revived again towards the end of WWII in 1944, for expanding the melting shop and mills. All of the plans did not come to fruition but are an interesting view of what might have occurred in different circumstances.
Some of the series show the S, T and U furnace and
one shows a third melting shop at right angles with U and V tilting furnaces.
Another shows the Cogging Mill moved at right angles to run parallel to and
just North of where the 4-high plate mill was later installed. Other drawings
show two off 3-high plate mills, the second (from Dorman Long) in parallel
with the existing 3-high plate mill, and with a second line of shears serving
the second mill. The second mill was to cost £28,000, within a £63,740
expansion in 1936. By 1944 a medium mill expansion was costed at £1,700,000,
plus a jobbing mill at £150,000.
In 1947 Colvilles plans were for a light plate mill at Clydebridge, which with ancilliaries would cost £2m.
In 1951 Colvilles development plans recognised that
the development of continuous strip rolling would lead to the close down of
hand operated sheet mills. It was proposed that a 4-stand continuous strip
mill would be installed at Clydebridge and that the coils of strip produced
would be sent to Smith and McLeans Gartcosh works, where the hand mills would
be replaced with cold rolling plant.
Installation of a fourth blast furnace at Clyde Iron Works was also proposed. The Colvilles board, the Iron and Steel Corporation and the Ministry of Supply, approved its construction. However, a shortage of coking coal in Scotland meant that construction at Clyde Iron would prevent conversion to hot metal working at Motherwell, and so the furnace eventually was constructed at Motherwell.
By 1956 Colvilles plans for Clydebridge included a 4-high plate mill, together with four off 4-high continuous stands for rolling light plates and sheets. A 44-inch slabbing mill was to be built at Ravenscraig to serve the 14-foot plate mill at Dalzell, but eventually a new wide plate mill was to be built at Ravenscraig, rather than at the confined site at Dalzell. Colvilles did not believe that demand would support a full scale continuous strip mill. Fortunately for Clydebridge, the planning of the 4-high plate mill was made before the Iron and Steel Board considered UK wide proposals from other works such as Appelby Frodingham.
Later in 1956 the plan for Clydebridge was revised to replace the existing 3-high plate mill with two off 4-high stands in tandem, plus provision for the future addition of stands for rolling light plates and sheets.
Subsequent discussions on the location of a strip mill in the UK lead to the Prime Minister announcing, on 18 November 1958, that there would be two strip mills, one at Newport South Wales and one at Ravenscraig. Once the Ravenscraig Strip Mill was settled the Clydebridge mill proposal reverted to a single 4-high stand plate mill.