FOREWORD This Recommended Practice for Planning@ Designing@ and Constructing Fixed Offshore Platforms contains engineering design principles and good practices that have evolved during the development of offshore oil resources. Good practice is based on good engineering; therefore@ this recommended practice consists essentially of good engineering recommendations. In no case is any specific recommendation included which could not be accomplished by presently available techniques and equipment. Consideration is given in all cases to the safety of personnel@ compliance with existing regulations@ and antipollution of water bodies. Metric conversions of customary English units are provided throughout the text of this publication in parentheses@ e.g.@ 6 in. (152 mm). Most of the converted values have been rounded for most practical usefulness; however@ precise conversions have been used where safety and technical considerations dictate. In case of dispute@ the customary English values should govern. Offshore technology is growing rapidly. In those areas where the committee felt that adequate data were available@ specific and detailed recommendations are given. In other areas general statements are used to indicate that consideration should be given to those particular points. Designers are encouraged to utilize all research advances available to them. As offshore knowledge continues to grow@ this recommended practice will be revised. It is hoped that the general statements contained herein will gradually be replaced by detailed recommendations. Reference in this practice is made to the latest edition of the AISC Specification for the Design@ Fabrication and Erection of Structural Steel for Buildings (see Section 2.5.1a). While the use of latest edition of this specification is still endorsed@ the use of the new AISC Load Resistance Factor Design (LRFD)@ First Edition is specifically not recommended for design of offshore platforms. The load and resistance factors in this new code are based on calibration with building design practices and are therefore not applicable to offshore platforms. Research work is now in progress to incorporate the strength provisions of the new AISC LRFD code into offshore design practices. In this practice@ reference is made to ANSI/AWS D1.1-2002 Structural Welding Code - Steel. While use of this edition is endorsed@ the primary intent is that the AWS code be followed for the welding and fabrication of Fixed Offshore Platforms. Chapters 8@ 9@ and 10 of the AWS Code give guidance that may be relevant to the design of Fixed Offshore Platforms. This Recommended Practice makes specific reference to Chapter 9 and 10 for certain design considerations. Where specific guidance is given in this API document@ as in Sections 4 and 5@ this guidance should take precedence. This standard shall become effective on the dateprinted on the cover but may be used voluntarily from the date of distribution. Attention Users: Portions of this publication have been changed from the previous edition. The locations of changes have been marked with a bar in the margin@ as shown to the left of this paragraph. In some cases the changes are significant@ while in other cases the changes reflect minor editorial adjustments.The bar notations in the margins are provided as an aid to users as to those parts of this publication that have been changed from the previous edition@ but API makes no warranty as to theaccuracy of such bar notations. Note: This edition supersedes the 20th Edition dated July 1@ 1993. This Recommended Practice is under jurisdiction of the API Subcommittee on Offshore Structures and was authorized for publication at the 1969 standardization conference. The first edition was issued October 1969. API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however@ the Institute makes no representation@ warranty@ or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal@ state@ or municipal regulation with which this publication may conflict. Suggested revisions are invited and should submitted to the Standards Manager@ American Petroleum Institute@ 1220 L Street@ N.W.@ Washington@ D.C. 20005.