Cov khoom siv hlau yog thawj zaug galvanized los tsim galvanized sawb hlau, thiab tom qab ntawd cov yeeb nkab steel ua los ntawm kev ua haujlwm tom qab hu ua galvanized sawb steel yeeb nkab, tseem hu ua pre-galvanized steel yeeb nkab.Ua ntej, cov khoom siv hlau yog tsim los rau hauv cov kav hlau zoo tib yam ntawm cov khoom siv welde ...
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