Abstract: In a membrane filter system composed of a plurality of tubular membrane supporting pipes disposed in parallel and arranged to conduct a flow of concentrate under pressure, there is provided a deflection sleeve connecting together the ends of two of the pipes to conduct concentrate between the pipes in such a manner that concentrate is deflected as it passes through the sleeve and such deflection produces forces in the system parallel to the axes of the pipes, and a connecting unit connected between each pipe end and the sleeve for connecting them together and transmitting such axial forces from the sleeve to each supporting pipe.