Piston rings were really bad in the early days.
Remember, this was all iron, not steel. The mass production of steel didn't get going until the 1880s. It's amazing that railroads predate steel.
Remember, this was all iron, not steel. The mass production of steel didn't get going until the 1880s. It's amazing that railroads predate steel.
So what you got may have been called cast iron but what it actually was might be pig iron, gray cast iron, ductile iron, and even a bit of steel and possibly carbides mixed in. Properties varied - sometimes by a lot.
If you know even a bit about metals then when you hear "cast iron piston ring" you imagine that ring to have certain properties that match a specific type of cast iron. But in those days every single ring might vary significantly entirely due to the ore load the foundry happened to get, how they melted/cast it, how it was cooled, etc.
That was the problem with the Bessemer converter. It took about 10,000 trials and advances in analytical chemistry to make that process work. Once the thing starts the chemical reaction that makes it go, all you can do is watch until something steel-like comes out. With the wrong inputs, you get crappy steel. Bessemer only got good steel because he accidentally had the right composition of inputs. He had to refund some customers who bought converters and got nothing useful out.
The Romans could have built a Bessemer converter, but it wouldn't have worked consistently.
It took a long time to get open hearth furnaces working. They're a collection of brickwork chambers and plumbing which can get up to 3000F and hold that temperature. The exhaust gases heat brickwork which in turn heats incoming air. It takes some understanding of thermodynamics, and really good firebricks, to make such a furnace. Otherwise the furnace never gets hot enough to make steel. Much of the early history of iron and steel making is the story of trying to get something done with a furnace that isn't hot enough to do it right.