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Date: August 2011 To: Purchasers of API 650, Welded Steel Tanks for Oil Storage, 11th Edition Re: Addendum 3 This package contains Addendum 3 of API 650, Welded Tanks for Oil Storage, 11th Edition. This package consists of the pages that have changed since the June 2007 printing of the 11th edition, Addendum 1 dated November 2008, and Addendum 2 dated November 2009. To update your copy of API 650, replace, delete, or add the following pages as indicated. Part of Book Changed Cover Front Matter Section 1 Section 2 Section 3 Section 4 Section 5 Section 7 Section 8 Section 9 Section 10 Appendix A Appendix AL Appendix C Appendix E Appendix EC Appendix F Appendix G Appendix H Old Pages to be Replaced front and back covers title page iii – iv vii – xiii 1-1 – 1-4 2-1 – 2-4 3-1 (+blank) 4-1 – 4-16 5-1 – 5-80 7-1 – 7-2 7-5 – 7-6 8-3 – 8-7 (+blank) 9-1 – 9-2 10-1 – 10-2 A-1 – A-2 A-9 – A-10 AL-7 – AL-8 AL-13 – AL-14 AL-19 – AL-20 C-1 – C-2 E-3 – E-4 E-19 – E-22 EC-3 – EC-10 EC-19 – EC-20 F-1 – F-6 G-1 – G-10 H-3 – H-8 New Pages front and back covers title page iii – iv vii – xiii (+ blank) 1-1 – 1-4 2-1 – 2-4 3-1 – 3-2 4-1 – 4-16 5-1 – 5-81 (+blank) 7-1 – 7-2 7-5 – 7-6 8-3 – 8-7 (+blank) 9-1 – 9-2 10-1 – 10-2 A-1 – A-2 A-9 – A-10 AL7 – AL8 AL-13 – AL-14 AL-19 – AL-20 C-1 – C-2 E-3 – E-4 E-19 – E-22 EC-3 – EC-10 EC-19 – EC-20 F-1 – F-6 G-1 – G-10 H-3 – H-8 Appendix I Appendix J Appendix K Appendix L Appendix M Appendix P Appendix R Appendix S Appendix SC Appendix V Appendix X I-1 – I-2 I-5 – I-6 J-1 – J-4 K-1 – K-4 L-3 – L-16 L-19 – L-20 M-1 – M-2 M-5 – M-6 P-1 – P-22 R-1 (+ blank) S-1 – S-6 S-11 (+ blank) SC-1 – SC-2 V-1 – V-16 V-21 – V-22 X-1 – X-2 X-5 – X-10 I-1 – I-2 I-5 – I-6 J-1 – J-4 K-1– K-4 L-3 – L-16 L-19 – L-20 M-1 – M-2 M-5 – M-6 P-1 – P-22 R-1 (+ blank) S-1 – S-6 S-11 (+ blank) SC-1 – SC-2 V-1 – V-16 V-1 – V-22 X-1 – X-2 X-5 – X-10 The parts of the text, tables, and figures that contain changes are indicated by a vertical bar and a small “11” in the margin. 08 Welded Tanks for Oil Storage API STANDARD 650 ELEVENTH EDITION, JUNE 2007 ADDENDUM 1: NOVEMBER 2008 ADDENDUM 2: NOVEMBER 2009 ADDENDUM 3: JUNE 2011 EFFECTIVE DATE: SEPTEMBER 1, 2011 08 Welded Tanks for Oil Storage Downstream Segment API STANDARD 650 ELEVENTH EDITION, JUNE 2007 ADDENDUM 1: NOVEMBER 2008 ADDENDUM 2: NOVEMBER 2009 ADDENDUM 3: JUNE 2011 EFFECTIVE DATE: SEPTEMBER 1, 2011 SPECIAL NOTES API publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed. Neither API nor any of API’s employees, subcontractors, consultants, committees, or other assignees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibility for any use, or the results of such use, of any information or process disclosed in this publication. Neither API nor any of API’s employees, subcontractors, consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights. Classified areas may vary depending on the location, conditions, equipment, and substances involved in any given jurisdiction. Users of this Standard should consult with the appropriate authorities having jurisdiction. 07 Users of this Standard should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein. API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations to comply with authorities having jurisdiction. Information containing safety and health risks and proper precautions with respect to particular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety data sheet. 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 authorities having jurisdiction with which this publication may conflict. API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are not intended to obviate the need for applying sound engineering judgment regarding when and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices. Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such products do in fact conform to the applicable API standard. All rights reserved. No part of this work may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, N.W., Washington, D.C. 20005. Copyright © 2007, 2008, 2009, 2011 American Petroleum Institute NOTICE INSTRUCTIONS FOR SUBMITTING A PROPOSED REVISION TO THIS STANDARD UNDER CONTINUOUS MAINTENANCE This Standard is maintained under continuous maintenance procedures by the American Petroleum Institute for which the Standards Department. These procedures establish a documented program for regular publication of addenda or revisions, including timely and documented consensus action on requests for revisions to any part of the Standard. Proposed revisions shall be submitted to the Director, Standards Department, American Petroleum Institute, 1220 L Street, NW, Washington, D.C. 20005-4070, standards@api.org. iii FOREWORD This Standard is based on the accumulated knowledge and experience of Purchasers and Manufacturers of welded oil storage tanks of various sizes and capacities for internal pressures not more than 17.2 kPa (21/2 pounds per square inch) gauge. This Standard is meant to be a purchase specification to facilitate the manufacture and procurement of storage tanks for the petroleum industry. 07 08 07 If the tanks are purchased in accordance with this Standard, the Purchaser is required to specify certain basic requirements. The Purchaser may want to modify, delete, or amplify sections of this Standard, but reference to this Standard shall not be made on the nameplates of or on the Manufacturer’s certification for tanks that do not fulfill the minimum requirements of this Standard or that exceed its limitations. It is strongly recommended that any modifications, deletions, or amplifications be made by supplementing this Standard rather than by rewriting or incorporating sections of it into another complete standard. The design rules given in this Standard are minimum requirements. More stringent design rules specified by the Purchaser or furnished by the Manufacturer are acceptable when mutually agreed upon by the Purchaser and the Manufacturer. This Standard is not to be interpreted as approving, recommending, or endorsing any specific design or as limiting the method of design or construction. Shall: As used in a standard, “shall” denotes a minimum requirement in order to conform to the specification. 07 Should: As used in a standard, “should” denotes a recommendation or that which is advised but not required in order to conform to the specification. • This Standard is not intended to cover storage tanks that are to be erected in areas subject to regulations more stringent than the specifications in this Standard. When this Standard is specified for such tanks, it should be followed insofar as it does not conflict with local requirements. The Purchaser is responsible for specifying any jurisdictional requirements applicable to the design and construction of the tank. After revisions to this Standard have been issued, they may be applied to tanks that are to be completed after the date of issue. The tank nameplate shall state the date of the edition of the Standard and any revision to that edition to which the tank has been designed and constructed. • 07 Each edition, revision, or addenda to this API Standard may be used beginning with the date of issuance shown on the cover page for that edition, revision, or addenda. Each edition, revision, or addenda to this API Standard becomes effective six months after the date of issuance for equipment that is certified as being constructed, and tested per this Standard. During the six-month time between the date of issuance of the edition, revision, or addenda and the effective date, the Purchaser and the Manufacturer shall specify to which edition, revision, or addenda the equipment is to be constructed and tested. 11 DELETED 07 Suggested revisions are invited and should be submitted to the Downstream Segment, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. iv Contents Page 1 1.1 1.2 1.3 1.4 1.5 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Responsibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Documentation Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Formulas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 08 3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 07 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 Structural Shapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8 Piping and Forgings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8 Flanges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15 Bolting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15 Welding Electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15 Gaskets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15 09 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 Joints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6 Special Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7 Bottom Plates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8 Annular Bottom Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10 Shell Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12 Shell Openings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19 Shell Attachments and Tank Appurtenances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-49 Top and Intermediate Stiffening Rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-58 Roofs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-70 Wind Load on Tanks (Overturning Stability) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-77 Tank Anchorage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-79 09 6 6.1 6.2 Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 Shop Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 07 7 7.1 7.2 7.3 7.4 7.5 Erection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Details of Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inspection, Testing, and Repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Repairs to Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dimensional Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 7-1 7-1 7-4 7-7 7-8 08 8 8.1 8.2 8.3 8.4 Methods of Inspecting Joints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radiographic Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Magnetic Particle Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ultrasonic Examination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Liquid Penetrant Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 8-1 8-4 8-4 8-5 vii 1-1 1-1 1-3 1-3 1-4 1-4 09 07 09 07 08 09 07 07 08 11 08 11 11 11 11 08 08 Page 8.5 8.6 Visual Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5 Vacuum Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6 9 9.1 9.2 9.3 9.4 Welding Procedure and Welder Qualifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Qualification of Welding Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Qualification of Welders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Identification of Welded Joints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 10.1 10.2 10.3 Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nameplates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Division of Responsibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 9-1 9-1 9-2 9-2 10-1 10-1 10-2 10-2 Appendix A Optional Design Basis for Small Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1 07 08 08 09 09 Appendix AL Aluminum Storage Tanks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AL-1 Appendix B Recommendations for Design and Construction of Foundations for Aboveground Oil Storage Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1 08 Appendix C External Floating Roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 Appendix D Technical Inquiries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1 07 Appendix E Seismic Design of Storage Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1 Appendix EC Commentary on Appendix E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EC-1 Appendix F Design of Tanks for Small internal Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1 09 Appendix G Structurally-Supported Aluminum Dome Roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1 Appendix H Internal Floating Roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H-1 Appendix I Undertank Leak Detection and Subgrade Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-1 07 Appendix J Shop-Assembled Storage Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J-1 Appendix K Sample Application of the Variable-Design-Point Method to Determine Shell-Plate Thickness K-1 Appendix L API Std 650 Storage Tank Data Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L-1 09 Appendix M Requirements for Tanks Operating at Elevated Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . M-1 Appendix N Use of New Materials That Are Not Identified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N-1 Appendix O Recommendations for Under-Bottom Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O-1 08 Appendix P Allowable External Loads on Tank Shell Openings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P-1 Appendix R Load Combinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R-1 09 Appendix S Austenitic Stainless Steel Storage Tanks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S-1 Appendix SC Stainless and Carbon Steel Mixed Materials Storage Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . SC-1 Appendix T NDE Requirements Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T-1 07 Appendix U Ultrasonic Examination In Lieu of Radiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . U-1 Appendix V Design of Storage Tanks for External Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V-1 09 08 Appendix W Commercial and Documentation Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .W-1 07 Appendix X Duplex Stainless Steel Storage Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X-1 08 Appendix Y API Monogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Y-1 09 viii