DIPERMET unit determines the t0-value of steel plates to be enameled. The t0-value is the time required for the diffusion of hydrogen, generated on one side of a steel plate, to the other side of the plate. The t0-value is in direct relation to the effective diffusion coefficient (Deff) of the atomic hydrogen solved in the steel sheet. The t0-values determined for plates of various thicknesses will be normalized to a conventional plate thickness of one mm in proportion to the quadrates of the individual plate thicknesses. The t0-limit value to be used as qualification basis will be recorded experimentally.