Dual pipe heat exchangers in safety format are suitable for deployment wherever circumstances may arise where the contamination of water coolant or the mixing of two media must be avoided. This is the case, for example, with an oil cooler cooled with fluvial water. The dual pipe safety heat exchanger is constructed as a “pipe in pipe” system with dual pipe plates. In the event of a pipe break, it prevents the cross-mixing or contamination of the pipe-side and shell-side media. A possible leak is recognised by a decrease or increase in the pressure of a buffer medium in the control room and is notified by means of an electrical signal transmitted via a pressure switch.