FOREWORD: These specifications were prepared by the Special A. P. I. Committee on the Standardization of Specifications for Steel and Iron Pipe for Oil Country Tubular Goods@ appointed by the Board of Directors of the American Petroleum Institute. 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 all the oil producing districts@ under the sponsorship of the American Petroleum Institute@ in order that the specifications might be national in scope. The American Society for Testing Materials rendered valuable assistance in outlining the scope of the work and in preparing tentative specifications. The tables on drill pipe were prepared by the Special A. P. I. Committee on the Standardization of Rotary Drilling Equipment. The tables on tubing were prepared by the Special A. P. I. Committee on the Standardization of Pumping Equipment as Applied to the Production of Oil. Tables on line pipe will eventually be added. The first edition of this specification@ containing tables on casing only@ was issued in 1924 as Specification No.5@ which was amended in June@ 1925@ at the Semi-annual Standardization Conference held at Dallas@ Texas@ and re-issued as A. P. I. Pipe Specification No.5-A. A. P. I. Pipe Specification No. 5-A was later modified and amended at the Semi-annual Standardization Conference held at Colorado Springs@ Colorado@ in June@ 1926@ when the tables on drill pipe and tubing were approved@ and re-issued in its present form as A. P. I. Pipe Specification No.5-A@ Second Edition.