PVC法兰球阀英文名平焊法兰slippon flange(SF)对焊法兰butt weld flange(BWF)凹凸法兰female and male flange（MFM）带颈法兰with neck flange(NF)法兰盖flange cover(FC)盲法兰Blind flange(BF)平面管道法兰Full Face（FF)凸面管道法兰凸面Raised Face（RF）凸面管道法兰凸面Raised Face（RF）环连接面...