In a steam locomotive, the dry pipe is the route the steam generated in the boiler passes out to be used. It generally begins in the steam dome, the highest point in the boiler, because it is important that water does not get into it (water in the steam can destroy cylinders and other apparatus). From there, it generally passes forward through the boiler to emerge from the front tube sheet into the smokebox. In a locomotive that uses saturated steam, it passes from there straight into the valve chests for use in the cylinders, while in a superheated locomotive it first takes a detour through the superheater.