The overpressure protection of various types of cryogenic vessels is covered by a number of International Standards. Helium cryostats, however, include additional components such as superconducting magnets and cavities, electrical heaters and control valves with associated piping, which significantly influence the potential risk. At the European Committee for Standardization CEN, a new working group was hence founded as CEN/TC 268/WG6, dealing with ‘Specific helium technology applications’. Its aim is to develop a European Standard for the protection of helium cryostats against excessive pressure that is harmonized with the European Pressure Equipment Directive. It will cover the typical conditions in accidental scenarios in order to harmonize the risk assessment as well as design practices for the pressure relieving systems. We report about the general concept of this new Standard, its structure and content, and the actual status of the project.