FOREWORD (a) This specification was prepared by the API Committee on the. Standardization of Oil Country Tubular Goods. (b) This specification covers chemical and physical properties and processes of manufacture of casing@ drill pipe@ and tubing@ with dimensions on diameter@ thicnkness@ lengths@ threads@ etc@ and master gages. (c) The work was initiated under the auspices of the Mid-Continent Oil and Gas Association in 1921; It was decided in 1922 to enlarge the Committee to include al lthe oil producing districts@ under the sponsorship of the American Petroleum Institute in order that the specifications might be national in scope. (d) The American Society for Testing Materials rendesed valuable assistance in outlining the scope of the work and in preparing tentative specifications. (e) The tables on drill pipe were prepared by the API Committee on the Standardization of Rotary Drilling Equipment. (f) The tbales on tubing were prepared by the API Committee on the Standardization of Pumping Equipment and Engines as Applied of the Production of Oil.