Fluorine gas (30%) escaping through leaks in stainless steels at 7 and 93 bars of pressure did not cause metal-fluorine fires

• No ignition of stainless steels with 30 % F 2 at 7 bars escaping from leaks. • No ignition of stainless steels with 30 % F 2 at 93 bars escaping from leaks. • Stainless steels can be used with 30 % F 2 under the described conditions, if the usual safety requirements and pretreatments are followed. We investigated whether diluted fluorine gas (Solvaclean N, 30 % F 2 , 40 % N 2 , 30 % Ar) escaping from test leaks in prepassivated tubes or unpassivated disks can cause a metal fluorine fire. Tested tubes and disks were made out of stainless steel, 316 L (1.4404) or 316Ti (1.4571). For the simulation of damage leading to tube leaks, cuts were made using a hacksaw and an angle grinder, or a tube was squeezed together at its open end. A metal drill bit was used to make holes into test disks. Visual observations were made to determine whether corrosion, sparking, or a metal fluorine fire would occur when F 2 flows through the leaks. The tests were documented photographically, and the temperature changes close to the test leaks were tracked using a thermocouple. Under the conditions selected here, no ignition could be observed in any case, whether the F 2 escaped at 7 bars within 90 s or at 93 bars within a single second in a burst-like scenario. In addition, no temperature increase was detected.