1. Cov txheej rwb thaiv tsev yuav tsum nyob ze ntawm cov yeeb nkab, thiab yuav tsum tsis muaj qhov khoob lossis xoob.
2. Lub thickness ntawm cov rwb thaiv tsev txheej yuav tsum tau txiav txim raws li qhov nruab nrab kub thiab siv ib puag ncig, thiab feem ntau yuav tsum tsis pub tsawg tshaj 100 hli.
3. Cov txheej txheej txheej txheej rwb thaiv tsev yuav tsum du thiab zoo nkauj, thiab cov pob qij txha yuav tsum nruj, tsis txhob poob los yog tawg.
4. Cov ntaub ntawv rwb thaiv tsev yuav tsum ua raws li cov qauv hauv lub tebchaws, thiab cov khoom siv hluav taws xob tsis zoo, muaj kev puas tsuaj, corrosive thiab lwm yam khoom tsis tsim nyog yuav tsum tsis txhob siv.