Ukuze sifumanise ubukhulu bodonga lwetyhubhu ye-3/16, kufuneka sazi ububanzi bangaphandle (OD) kunye nobubanzi bangaphakathi (ID) betyhubhu. Ukuba ububanzi bangaphandle buyi-3/16″ kwaye akukho lwazi luthile lunikiweyo malunga nobubanzi bangaphakathi, asinakubala ngokuchanekileyo ubukhulu bodonga. Ubukhulu bodonga bungahluka ngokuxhomekeke kuhlobo oluthile lwetyhubhu kunye nemigangatho yokuvelisa.