The wall thickness, or more precisely wall thickness, describes the depth of a wall. This plays a special role in casting technology processes, but also in pressure vessels, hoses, and pipelines as well as bending processes, the wall thickness can be decisive for a guaranteed functional efficiency of a component. If the wall thickness is too thin, areas of the wall are in danger of collapsing or bursting. In order to statistically calculate a necessary wall thickness for piping and pressure vessels, the boiler formula is used. It specifies mechanical stresses in rotationally symmetrical bodies loaded by internal pressure. Neither deformation assumptions nor elasticity quantities are necessary to calculate these stresses, since the formula is based on a force equilibrium as a membrane stress. A wide range of metrological methods, tools and devices are available for measuring and testing the wall thickness of various bodies, depending on the specific measurement task and the conditions under which the measurement has to take place.