|Credit: McIntyre, J., Osmonics|
In an article addressing ways to clean the jacket of a glass-lined steel reactor, James McIntyre talks about the reasons why pharmaceutical process chemistry tends to use glass:
Glass-lined reactors are used in virtually all of the world's pharmaceutical manufacturing facilities. There are several key reasons for their selection by design engineers.
In a pharmaceutical process, cleanability is critical. Between batches, each reactor and its associated process equipment must be thoroughly cleaned in order to assure product quality and minimize heat transfer resistance caused by product buildup. Fortunately, glass has a high degree of surface smoothness which makes it easy to clean using noncorrosive, low pressure cleaning systems.
Glass is also chemically resistant and as a result, can serve for many years in environments that would quickly render most metal vessels unserviceable. Aggressive reaction environments also tend to dissolve metals from unlined mild steel or alloy reactors. These metals can compromise product quality in an industry where purity is essential. By comparison, the glass-lining protects the base metal so effectively that the relatively benign heat transfer fluids used in the jacket space will generally attack the jacket and reactor exterior long before the reaction environment compromises the glass-lined interior of the vessel.As the article addresses, the glass/steel jacket around the reactor that does all of your heating and cooling needs to be maintained and cleaned. If you don't, you can get scale buildup from plant water (among other problems) which can limit the flow of the heating/cooling fluid.
Now that's not a problem you tend to have with a 3-necked round bottom flask in the lab! (A weird question: I've seen heating mantles for 72 liter flasks -- what's the largest heating mantle out there?)