Fire safe ? secondary metal - to - metal seal acts as backup if primary seal is destroyed by fire . valves ordered for compliance with api 607 will be provided with graphite packing and gaskets 氯气应用-可提供能够满足氯气协会第6小册子所列的全部标准和规定的阀门,包括通风球的预备,流向箭头,以及为了防止污染而进行的清洗和包装。