Were Richelieu's boilers more advanced than contemporary US high-temperature, high-pressure plants?
Short answerThey were a significant French move toward high-temperature, high-pressure machinery, though the answer does not rank them above the American systems.
NotesThe French plant pursued the same broad high-temperature, high-pressure direction as the US Navy and was technically interesting. The brief answer stops short of calling it more advanced than the American installation. Similar engineering goals do not establish identical pressures, reliability, or operational maturity. The comparison therefore remains deliberately cautious.