... Manufacture standardsMSS SP81;JB/T 8691-1998Face to Face DimensionMSS SP81,MSS SP135,ASME B16.35,ASME ... prevent solid grain scour, wear to seal face,ensure valve seal lasting effective.2, single seat design ... seat, one-way sealing with pressure.ZHONGCHENG'S special advantages:1, It can be used as bleeder/inlet valve in ... 81, MSS SP-135,ASME B16.342. Face to face dimention standard:MSS SP-81, MSS SP-135 ...