Valve ndi gawo lowongolera pamapaipi operekera madzimadzi.Amagwiritsidwa ntchito kusintha gawo la mayendedwe ndi njira yapakati.Lili ndi ntchito za kusokoneza, kudula, kugwedeza, cheke, shunt kapena kuchepetsa kupanikizika kwa kusefukira.