Extraction systems for dust-laden filter systems are not only composed of fans, silencers, filter systems and cyclones, but also pipe lines (usually operating under low-pressure). This low-pressure has an advantage with regard to tightness; however, it also leads to higher demands on stability. Therefore, pressure, temperature and external loads (such as wind forces and bearing forces) are taken into consideration when designing the pipe – the thickness of the sheet metal, the flanges, as well as stiffening rings and inner reinforcements, are all specified in the design.