Cov kav dej uas muaj lub taub nominal ntau dua 50mm yuav tsum tsis txhob siv cov koom haum.
Cov kav hluav taws xob, raws li lub npe qhia, yog cov kav dej uas tsim los rau kev tua hluav taws. Vim yog cov kev cai tshwj xeeb, cov tuab thiab cov khoom siv ntawm cov kav dej tua hluav taws muaj cov kev cai tshwj xeeb, thiab cov xim liab yog txau los thauj cov dej tua hluav taws.
Cov kav hluav taws tua hluav taws yog hais txog cov khoom siv hluav taws xob uas siv rau kev tua hluav taws, txuas cov khoom siv hluav taws xob thiab cov khoom siv hluav taws xob, thiab xa cov dej tua hluav taws, roj lossis lwm yam xov xwm.
Txij li thaum cov kav hluav taws kub feem ntau nyob rau hauv lub xeev zoo li qub, cov kev cai rau cov kav dej yog nruj heev. Lub raj xa dej yuav tsum tiv taus siab, corrosion thiab kub kub.
