The invention relates to a fluid conduit piece (8) for passing therethrough a spontaneously exothermic working fluid such as a synthetic polymer, a cellulose derivative and a solution on the basis of cellulose, water and amino oxide, said fluid conduit piece comprising a working fluid zone (9) through which said working fluid flows. The aim of the invention is to prevent the fluid conduit piece and other fluidic devices from being damaged in the event of a spontaneous exothermic reaction in the working fluid. To this end, the fluid conduit piece is provided with an anti-rupture device (1) for the purpose of pressure relief. Said anti-rupture device has a pressure equalizing volume (7) that, once a predetermined rupture pressure is exceeded, can be converted from a normal operation state in which the pressure equalizing volume is separated from the working fluid zone into a rupture state in which the pressure equalizing volume is linked with the working fluid zone. The pressure equalizing volume is at least partially disposed in the working fluid zone and the working fluid at least partially flows around it, thereby reducing the size of the fluid conduit piece.