Txij li cov hlau purlins yog tsim los ntawm txias-khoov nyias-walled hlau nyob rau hauv chav tsev kub, cov khoom yuav tsim ib tug txias dabtsi yog khoov nyhuv.
Nws yog tsim rau ru tsev thiab phab ntsa kab teeb nyob rau hauv steel qauv tej yaam num. Thaum nws los txog khi rods, nws feem ntau yog hais txog cov hlau puag ncig uas khi cov hlau purlins. Txhawm rau muab nws bluntly, nws yog tuab steel tuav. Nws tseem yog txhawm rau txhim kho kev ruaj ntseg ntawm purlins kom cov purlins tsis yooj yim los ua tsis ruaj khov thiab puas nyob rau hauv qee qhov sab nraud. Cov ntawv hla ntu ntawm cov purlins feem ntau yog H-shaped steel, C-puab, Z-shaped, thiab lwm yam, thiab lawv txoj haujlwm yog txo qhov ncua sij hawm ntawm lub vaj huam sib luag hauv tsev me me thiab txhim kho lub ru tsev vaj huam sib luag.
