Bronze bushing can be used in gate valves. We often use bronze for replacement bushings in older obsolete designs since its very easy to machine from a solid bar when we no longer can make castings of the old stem bushing. Bronze bushings are primarily used for motor and thrust gear units for Gate and globe valves.
We don't use bronze very often in new hand wheel operated valves mostly due to cost. Gate valves are typically made in larger volumes so many gate valves use a type of malleable iron casting which is cheaper and preforms well. Globe Valves are lower volume items so many stem bushings are made from bronze bar.
This is not a universal rule their are exceptions and not all globe valves have bronze stem bushings.
Use of materials for valves have been changing over the last fifty years for several reasons. Main reasons are raw material costs, and availabillity of new (plastic) materials as replacement.
