A device for heat exchange and positioning in a pipe. The device includes a central body containing a material for storing thermal energy by latent heat accumulation, to be placed in thermal exchange with a circulating surrounding fluid. The device also includes structure for positioning the central body in the volume. The positioning structure is connected to, and extends around, the central body The position structure is also connected to reserving passages that enable contact between the central body and the surrounding fluid and the circulation of the surrounding fluid.