FOREWORD a. This bulletin is under the jurisdiction of the Committee on Standardization of Tubular Goods. b. The purpose of this bulletin is to show the formulas used in the calculation of the various pipe properties given in API standards@ including background information regarding their development and use. Note: This is the second edition of this bulletin. The first edition was authorized for publication at the 1970 Standardization Conference as detailed in Circ PS-1398. Requests for permission to reproduce or translate aIl or any part of the material published herein should be addressed to the Director@ Production Department@ 300 Corrigan Tower Bldg.@ Dal/as@ Texas 75201.