21. A greater quantity of steam can be generated from a given quantity of water by superheating it. 22. It declined in popularity due to maintenance issues and because superheating provided similar efficiencies at lower cost. 23. In 1944 another engine was converted to superheating , but the second steam dome was not used. 24. Steel superheating , as short journeys allow little time for the superheater elements to reach working temperature. 25. Hawksworth decided that the declining quality of coal reaching Great Western depots necessitated a higher degree of superheating . 26. Marsh therefore built four more superheated locomotives and six without superheating , between February 1909 and March 1910. 27. Superheating also required alteration of the valve gear and piston valves were therefore used instead of slide valves.28. The heating surface of the boiler was, of which was superheating surface, while the grate area was. 29. Despite the success of the superheating the Dd boiler, it was still somewhat limited in steam raising capabilities. 30. A liquid at or above its boiling point will normally boil, though superheating can prevent this in certain circumstances.
