Most navies designed some degree of overload potential into their steam power plants, so that if one (or more) boilers were damaged and forced to shut down, then the remaining boilers could be forced to burn more fuel and so produce more steam to make up the difference. Turbines could be also be overloaded and most naval turbines had extra steam inlet valves that could admit extra steam in the secondary stages of the turbine. Additionally many turbines were specified to be able to handle more steam volume than their nominal full throttle figures.
HMS Prince of Wales nominal full power = 110,000shp at 230rpm but PoW produced 134000 shp at ~239rpm prior to intercepting Bismarck.
Renown had a nominal full power rating of 120,000shp but was reported to have produced 160,000shp on at least two occasions (apparently leading to reprimands from their Lordships in the Admiralty).
Special boiler trials were made in (I class destroyers) Icarus and Imogen with a forced draught of 9 to 10 inches. Imogen ran one boiler on 20 per cent overload, 16,000 S.H.P. for three hours. but had trouble with the brickwork. After repairs she ran on the same boiler for two hours at 30 per cent overload, 17,000 S.H.P. without trouble, reaching a speed of 24 knots. Then followed a trial on two boilers at 34,000 S.H.P. In Icarus after the first 20 per cent over load trial the boiler back had to be stiffened up and repairs carrieded out in the dockyard.
Note how the firebrick lining of the boiler furnace was damaged by the excess heat. The I class destroyers had 3 boilers and normal full power was 34,000shp from all three boilers.