Ma valve owunikira, ma valve osabwezera, apangidwa kuti aletse kutembenuka kwa kayendedwe ka madzi mu dongosolo la mapaipi. Ma valve awa amayatsidwa ndi zinthu zomwe zimayenda mupaipi.Kupanikizika kwa madzi omwe amadutsa mu dongosolo kumatsegula valavu, pomwe kutembenuka kulikonse kwa kayendedwe ka madzi kudzatseka valavu.

Valavu yowunikira ya API602  Ndi ya ma valve ang'onoang'ono oyezera kuthamanga kwambiri, omwe amapangidwa ndi chitsulo chopangidwa. Nthawi zambiri timawapanga mu swing check valve, piston check valve (lift check valve).Imapezeka m'mapangidwe atatu a maboni. Kapangidwe koyamba ndi Bolted Bonnet, yokhala ndi cholumikizira cha amuna ndi akazi, chozungulira, chopangidwa mu F316L/graphite. Gasket ya mphete imapezekanso ngati mungafune. Kapangidwe kachiwiri ndi boniti yolumikizidwa, yokhala ndi cholumikizira cholumikizidwa ndi ulusi komanso chotsekedwa.