If you want to go and see one working, they have two identical triple expansion engines at the Kempton Steam Museum. It is effing huge, 6 stories high and they fire it up on Steaming days. Same vintage at Titanics, but instead used for pumping London's water.
We went to visit De Woudagemaal in Friesland it has a separate boiler house where the coal fired boilers have been converted to gas oil fired, it was originally built in 1918 and is still in use as a backup or emergency pump to keep the water levels down in surrounding canals, with pumping excess water into the Ijsselmeer. They do power it up for the tourists to let them see it working, we were there at the end of the season and they had started stripping part of it down for maintenance.
It has 4 double expansion compound engines each driving 2 water pumps.
Boiler in maintenance, section on the right shows the gas oil jets and on the left they have been removed
When I live in the UK I visited a company in the west midlands that claimed they made the crank shafts for the Titanic engines . I also visited a company who made the anchor chain for the Titanic by hand forging