FOREWORD: (a) This specification was originally prepared by the API Committee on the Standardization of Oil Country Tubular Goods. Under procedures adopted Nov.@ 1945@ this specification was placed under the jurisdiction of the API Committee on Standardization of Valves and Fittings. (b) This specification covers dimensional standard. and gages@ and gaging practice@ for internal threads in valves@ fittings@ and flanges intended for use on tubular material@ except drill pipe@ manufactured in accordance with API Std. 5-A (Casing@ Drill Pipe and Tubing)@ and API Std. 5-L (Line Pipe). (c) The Committee on Standardization of Valves and Fittings has jurisdiction over other specifications on valves@ flanges and fittings.
API STD 6-A-1947 history
1957API STD 6-A-1957 SPECIFICATION FOR THREADS IN VALVES@ FITTINGS@ AND FLANGES (Seventh Edition)
1956API STD 6-A-1956 SPECIFICATION FOR THREADS IN VALVES@ FITTINGS@ AND FLANGES (Tentative) (Sixth Edition)
1947API STD 6-A-1947 SPECIFICATION FOR THREADS IN VALVES@ FITTINGS AND FLANGES (Tentative) (Fifth Edition)