... INSTITUTE Specification for Pipeline Valves Upstream Segment ANSI /API SPECIFICATION 6D lWENTY-THIRD EDITION, APRIL 2008 EFFECTIVE DATE: OCTOBER 1, 2008 ERRATA 1, JUNE 2008 ERRATA 2, NOVEMBER 2008 ... 6.1.4 Check valves Typical configurations for check valves are shown, for illustration purposes only, in Figures to 13 Check valves can also be of the wafer, axial flow and lift type Check valves ... Specification for Pipeline Valves ANSI /API SPECIFICATION 60 TWENTY-THIRD EDITION, APRIL 2008 EFFECTIVE DATE: OCTOBER 1, 2008 ERRATA 1, JUNE 2008 ERRATA 2, NOVEMBER 2008 ERRATA 3,...