Yas valve yog ib hom kev siv dav dav, nws muaj qhov zoo ntawm corrosion kuj, lub teeb yuag, hnav tsis kam, thiab lwm yam. Nws yog dav siv hauv tshuaj, petrochemical, kev tiv thaiv ib puag ncig thiab lwm yam lag luam.Hauv qab no yog cov keeb kwm kev loj hlob ntawm cov yas li qub.Xyoo 1950, w...
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