Urea tends to crystallise at standstill. Processes in which batch operation prevails must pay particular attention to the design of the mechanical seal. STB GmbH has developed special concepts for the application of urea processes, in particular for reactor seals and pump seals, which enable safe operation of urea applications. The design of the mechanical seal for urea from STB GmbH is dominated by the fact that breakaway torques at which the product crystallises, as in urea, are compensated. For these seals, we have also developed systems that provide a long-lasting factor for the mechanical seal.