The Analysis of a Boiler Safety Valve Recovered from SS Xantho
Author/s Kilpa, A.
Year of publication 2012
Report Number: No. 312
Only limited archaeological research has been conducted on boiler safety valves of mid nineteenth-century steamships. As a result, this lack of knowledge has led to assumptions that spring-loaded valves were used in this era because they were more suitable for the task, i.e. the rolling and pitching at sea had no effect on the force applied by the valve. Noted Maritime Historian Denis Griffiths (1997:58), for example, states that “initially safety valves were of the deadweight type, but spring-loaded safety valves became normal in the 1850s following their general adoption on railway locomotive boilers.” This study examines and reconstructs a safety valve, of a type once believed obsolete by the late 1850s, that archaeologists recovered from close proximity to the boiler of SS Xantho (1848–1872). An alternative perspective is presented which demonstrates that these devices were used at sea well into the 1870s, even though spring-loaded safety valves were preferred over deadweight and lever-weighted mechanisms. It was only at the end of the nineteenth century that improvements in the engineering and metallurgy of spring and pop safety valves had advanced to a point where their installation on steamships had the confidence of engineers, and government regulatory agencies such as the Board of Trade.