How many nights have I lain awake wondering about the construction of conditioning tanks in the 1950s? This should save you from a similar torment.
“The conditioning tanks are usually of glass-lined steel, or more recently of stainless steel. Copper was used at one time and such tanks are still in use, but it is unlikely that copper would be used for constructing new tanks; copper tanks should not be tinned, as this metal can be responsible for haze. Considerable pressures develop and for this reason steel tanks are preferable. They are usually of about 20-50 barrels in capacity. Glass-lined tanks need special care in cleaning. The glass is easily scratched or chipped, and in this condition it is difficult to keep clean and free from deposit. Only bristle brushes should be used for cleaning, on no account should wire brushes be used. Workmen entering the tank should have rubber overshoes and no one should be allowed to enter with nailed boots; they should be cautioned against letting spanners or other tools drop into the tank.”
"Brewing Theory and Practice" by E. J. Jeffery, 1956, pages 332 - 333.
Presumably this where the march to all stainless steel breweries began. Obviously, tanks of unlined ordinary steel wouldn’t work. And glass seems a rather fragile lining. Especially as any imperfections in the surface were likely to harbour sources of infection. Sounds like they were a pain the the arse to keep clean and undamaged.
I can see one big problem with copper tanks: the expense. And, of course, during wartime copper was urgently required by the munitions industry.
As with all brewing equipment cleanliness was vital. And there were plenty of spots that were tricky to keep clean.
“Conditioning tanks of whatever material should be thoroughly cleaned out with a stiff brush followed by liberal swilling with hot water as soon as they are empty. No deposit must be allowed to dry on. Particular care must be given to the fittings and washers connected with beer mains, sampling cocks, gauge glasses, thermometer pockets and so on, as deposits which harbour infection collect very readily at these spots. We have mentioned that wire brushes should not be used in glass-lined tanks, and even with copper tanks it is inadvisable to use them or to employ abrasives such as pumice. Small abraded particles of copper can be readily trapped in the crevices of the fittings and may oxidize and dissolve in the beer. A slight staining of the copper surface is of no account provided no scale is formed. Conditioning vessels must be provided internally with an efficient rouser, usually in the shape of a propeller fitted near the bottom of the tank, its shaft passing out through the side, top or bottom as most convenient, through a packing gland and driven from a pulley or by a separate electric motor. Special attention must be paid to the packing gland as a possible source of infection. The vessels may be cither vertical or horizontal.”
"Brewing Theory and Practice" by E. J. Jeffery, 1956, page 333.
Simple things like the fittings connecting pipes and other equipment could cause havoc in a brewery, if they became a source of infection. Brewers have been driven crazy by infections they couldn’t track down. One weak spot in all the miles of piping contained in a brewery was all it needed to big a brewery to its knees. The cases where the source couldn’t be found, usually ultimately led to a brewery’s closure. As in the sad case of Home Ales.
We’ll learn later of the essential role played by the rouser. There’s a lovely table I’ll be sharing that documents the process of conditioning a beer in a tank. It was all news to me. And more complicated than I’d anticipated.