Kev siv hluav taws xob tsawg, lub teeb yuag, rov ua dua tshiab, yog lub cim tshiab ntawm cov khoom zoo ib puag ncig, kev ua haujlwm ntev; txhim khu kev qha thiab yooj yim installation (kev sib txuas), tuaj yeem ua tau raws li qhov yuav tsum tau muaj ntawm ntau lub sijhawm tshwj xeeb, tsis tshua muaj kev xav tau ntawm cov yeeb nkab puag; zoo saj zawg zog, muaj zog tsis kam mus rau geological zog; zoo heev corrosion kuj.
