Design and Construction of Large, Welded, Low …

1 Date: March 2009 To: Purchasers of API 620, Design and Construction of large , welded , Low- pressure storage tanks , 11th Edition Re: Addendum 1 This package contains Addendum 1 of API 620, Design and Construction of large , welded , Low- pressure storage tanks , 11th Edition. This package consists of the pages that have changed since the February 2008 printing of the 11th Edition. To update your copy of API 620, replace, delete or add the following pages as indicated: Part of Book Changed Old Pages to be Replaced New Pages Cover Front Cover (+ blank) Front Cover (+ blank) Front Matter Title Page and Special Notes Title Page and Special Notes v ix (+ blank) v ix (+ blank) Section 1 1-1 1-3 (+ blank) 1-1 1-3 (+ blank)

2 Section 3 3-1 3-2 3-1 3-2 Section 4 4-3 4-4 4-3 4-4 Section 5 5-5 5-8 5-5 5-8 5-31 5-32 5-31 5-32 5-49 5-50 5-49 5-50 5-59 5-60 5-59 5-60 Section 6 6-1 6-6 6-1 6-6 Section 7 7-1 7-2 7-1 7-2 7-9 7-10 7-9 7-10 Section 9 9-1 9-2 9-1 9-2 Appendix A A-1 A-7 (+ blank) A-1 (+ blank) Appendix L L-1 L-11 (+ blank) L-1 L-8 Appendix Q Q-15 Q-16 Q-15 Q-16 Q-19 Q-20 Q-19 Q-20 Q-25 (+ blank) Q-25 (+ blank) Appendix R R-1 R-4 R-1 R-4 R-7 R-16 R-7 R-16 Appendix S S-1 S-6 S-1 S-6 Appendix U U-1 U-2 U-1 U-2 The parts of the text, tables, and figures that contain changes are indicated by a vertical bar and a small 09 in the margin.

3 Design and Construction of large , welded , Low- pressure storage TanksAPI STANDARD 620 ELEVENTH EDITION, FEBRUARY 2008 ADDENDUM 1, MARCH 2009 Design and Construction of large , welded , Low- pressure storage TanksDownstream SegmentAPI STANDARD 620 ELEVENTH EDITION, FEBRUARY 2008 ADDENDUM 1, MARCH 2009 Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be 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.

4 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 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 publications are published to facilitate the broad availability of proven, sound engineering and operating practices.

5 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 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 rights reserved.

6 No part of this work may be reproduced, translated, 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, , Washington, 2008, 2009 American Petroleum Institute0909 ContentsPage1 Scope .. General .. Coverage.. Limitations .. 1-32 References .. 2-13 Definitions .. Stress and pressure Terms .. Capacity Terms.

7 Tank Wall.. Welding Terms .. Other Terms .. 3-24 Materials .. General .. Plates.. Pipe, Flanges, Forging, and Castings .. Bolting Material .. Structural Shapes .. 4-95 Design .. General .. Operating Temperature .. Pressures Used in Design .. Loads.. Maximum Allowable Stress for Walls .. Maximum Allowable Stress Values for Structural Members and Bolts .. Corrosion Allowance.. Linings .. Procedure for Designing Tank Walls.

8 Design of Sidewalls, Roofs, and Bottoms .. Special Considerations Applicable to Bottoms That Rest Directly on Foundations.. Design of Roof and Bottom Knuckle Regions and Compression-ring Girders .. Design of Internal and External Structural Members .. Shapes, Locations, and Maximum Sizes of Wall Openings .. Inspection Openings .. Reinforcement of Single Openings .. Reinforcement of Multiple Openings.. Design of large , Centrally Located, Circular Openings in Roofs and Bottoms.

9 Necks and Their Attachments to the Tank .. Bolted Flanged Connections .. Cover Plates .. Permitted Types of Joints .. welded Joint Efficiency .. Plug Welds and Slot Welds.. Relieving .. Radiographic/Ultrasonic Examination .. Flush-type Shell Connection .. 5-6109090909vPage6 Fabrication .. General .. Workmanship .. Cutting Plates.. Forming Sidewall Sections and Roof and Bottom Plates.. Dimensional Tolerances .. Details of Welding .. Qualification of Welding Procedure.

10 Qualification of Welders .. Matching Plates .. Cleaning Surfaces to be welded .. Weather Conditions for Welding .. Reinforcement on Welds .. Merging Weld With Plate Surface .. Aligning of Main Joints .. Repairing Defects in Welds .. Matching Plates of Unequal Thickness.. Fitting Up of Closure Plates .. Thermal Stress Relief .. Peening Field Welds ..6-77 Inspection, Examination and Testing .. of Examiner .. Qualifications of Examiners .. Access for Inspector .. Facilities for Inspector.