1、 Prevention of tank bottom leakage A guide for the design and repair of foundations and bottoms of vertical, cylindrical, steel storage tanks PUBLICATION 183 Edition 2 Released by IHS. NOT FOR RESALE THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION Prevention of tank bottom leakage A guide
2、for the design and repair of foundations and bottoms of vertical, cylindrical, steel storage tanks PUBLICATION 183 Edition 2 Copyright 2011 The Engineering Equipment and Materials Users Association. A company limited by guarantee. Registered in England. Company number 477838. ISBN 978 0 85931 183 0
3、Imprint reference 06-2011 Registered and Trading Address 10-12 Lovat Lane London EC3R 8DN Telephone: +44 (0)20 7621 0011 Fax: +44 (0)20 7621 0022 E-mail: saleseemua.org Website: www.eemua.orgEEMUA Publication 183 A guide for the prevention of bottom leakage from storage tanks EEMUA ii ENGINEERING EQ
4、UIPMENT AND MATERIALS USERS ASSOCIATION About EEMUA The Engineering Equipment and Materials Users Association is usually known by its initials, EEMUA. EEMUA is governed by a Council of members. This Council is responsible for the policies, financing, membership, and strategy of the Association. Any
5、organisation that is a substantial user or purchaser of engineering products is eligible to apply to become a member of EEMUA. Membership is subject to the approval of Council. EEMUA Aims EEMUA aims to improve the safety, environmental and operating performance of industrial facilities in the most c
6、ost-effective way, pursuing and promoting leadership in industrial asset management by sharing engineering experiences and expertise, and by the active, enlightened promotion of the distinct interests of users of engineering products. These aims are achieved by various means, including: Providing th
7、e organisation within which networking, information sharing and collaboration among users on non-competitive technical matters can take place Influencing the way written regulations are interpreted and applied in practice Promoting and presenting members views, and encouraging the application of goo
8、d sound engineering practices Developing user guides, specifications, training and competency schemes Facilitating members participation in national and international standards making Influencing relevant national and European legislation and regulation. The income and resources of EEMUA are applied
9、 solely towards the promotion of the aims of the Association. No profit is transferred by way of dividend, bonus or otherwise to members. The work of the Association is mainly carried out by members representatives on EEMUA Technical Committees, Working Groups, and Forums, supported by EEMUA staff.
10、Incorporation, Membership and Other Information For the purposes of conducting its business, EEMUA is incorporated in England and Wales as a company, limited by guarantee, not having share capital. All usual aspects of company management and business administration are dealt with by the EEMUA Execut
11、ive Director, including policy implementation and leadership of the Executive team (the staff). A list of EEMUA publications for sale is given at the end of this Publication. The full list is also on the Associations website, including details of on-line shopping facilities. To enquire about corpora
12、te Membership, write to enquirieseemua.org or call +44 (0)20 7621 0011. EEMUA Publication 183 A guide for the prevention of bottom leakage from storage tanks EEMUA iii ABOUT THIS PUBLICATION Legal Aspects All rights, title and interest in this Publication belong to EEMUA. All rights are reserved. No
13、 part of this Publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording or other, without the express prior written agreement of the EEMUA Executive Director. Infringement of copyright is illegal and also
14、reduces the Associations income thereby jeopardising its ability to fund the production of future publications. It has been assumed in the preparation of this Publication that: the user ensures selection of those parts of its contents appropriate to the intended application; and that such selection
15、and application is correctly carried out by appropriately qualified and competent persons for whose guidance this Publication has been prepared. EEMUA and the individual members of the Work Group that prepared this EEMUA publication do not, and indeed cannot, make any representation or give any warr
16、anty or guarantee in connection with material contained herein. EEMUA and the individual members of the Work Group that prepared this EEMUA publication expressly disclaim any liability or responsibility for damage or loss resulting from the use or reliance on this Publication. Any recommendations co
17、ntained herein are based on the most authoritative information available at the time of writing and on current good engineering practice, but it is essential for the user to take account of pertinent subsequent developments and/or legislation. Any person who encounters an inaccuracy or ambiguity whe
18、n making use of this Publication is asked to notify EEMUA without delay so that the matter may be investigated and appropriate action taken. Consultation and Feedback EEMUA encourages constructive comments on this Publication from both Members of the Association and others. Comments should be sent o
19、n the standard feedback form, a copy of which is provided towards the end of this Publication. An electronic version of the feedback form is available from EEMUA - e-mail your request for a copy to enquirieseemua.org, telephone your request to +44 (0)20 7621 0011, or download the form from the EEMUA
20、 website at www.eemua.org. Submit comments by e-mail (preferred) or post. Comments are considered by the relevant EEMUA Technical Committees and may be incorporated in future editions of this Publication. New editions are publicised on the EEMUA website. EEMUA Publication 183 A guide for the prevent
21、ion of bottom leakage from storage tanks EEMUA iv EEMUA Publication 183 A guide for the prevention of bottom leakage from storage tanks EEMUA v Contents Foreword ix 1. Introduction and Scope . 1 1.1 Background 1 1.2 Legislation and Available Standards . 1 1.3 Scope 3 2. Tank Foundations: General Des
22、ign Considerations 5 2.1 General 5 2.2 Sand Pads 5 2.3 Sand Pad with Annular Ring of Coarse Material 6 2.4 Concrete Ring Wall 6 2.5 Concrete Raft: Plain and Piled Slab 7 2.6 Sand Pad Foundation with Crushed Stone Piles . 8 2.7 Design of Tank Foundations 8 2.7.1 Soil Investigations . 8 2.7.2 Soil Imp
23、rovements 9 2.7.3 Design Parameters 10 2.7.4 Foundation Materials 14 2.7.5 Construction . 15 3. Tank Bottoms: Designs 17 3.1 General 17 3.2 Tank Bottoms with Annular Plates 17 3.3 Tank Bottoms without Annular Plates . 18 3.4 Double Bottoms . 20 3.4.1. Double Bottoms in New Tanks 20 3.4.2. Double Bot
24、toms in Existing Tanks . 21 4. Main Causes of Tank Bottom Leakage . 25 4.1 General 25 4.2 Foundations 25 4.3 Settlement . 25 4.4 Corrosion of Bottom Plates 25 4.4.1 General 25 4.4.2 Contact Corrosion to Tank Bottoms and Annular Plates . 27 4.4.3 Bimetallic Corrosion . 27 4.4.4 External Bottom Corros
25、ion 28 4.4.5 Accelerated Corrosion of Hot Tanks 29 4.4.6 Retirement Criteria for Plate Thicknesses 29 5. Inspection Records and Techniques 31 5.1 Inspection and Records System . 31 5.1.1 General 31 5.1.2 Regular In-Service Inspection . 31 5.1.3 Regular Out-of-Service Inspection . 31 5.2 Inspection T
26、echniques 31 5.2.1 Inspection of Interconnecting Welds between Bottom Plates 31 5.2.2 Inspection of Bottom Plates 33 6. Other Measures for Preserving the Integrity of Tank Bottoms 45 6.1 General 45 6.2 Coating and Lining Systems 45 6.2.1 Paint Systems and Tank Linings 45 6.2.2 Glass Fibre/ Epoxy Res
27、in Laminates . 45 6.3 Drip Plate . 46 6.4 Tank Shell Skirt . 46 6.5 Corrosion Allowance/ Retirement Limits/ Local Repairs 47 EEMUA Publication 183 A guide for the prevention of bottom leakage from storage tanks EEMUA vi 6.5.1 Corrosion Allowance and Retirement Limits . 47 6.5.2 Local Repairs 47 6.6
28、Cathodic Protection 50 6.6.1 Sacrificial Anodes 50 6.6.2 Impressed Current Systems 50 6.6.3 Effect of Tank Foundations 51 6.6.4 Internal Cathodic Protection 51 6.6.5 Monitoring and Maintenance of CP Systems . 51 6.6.6 Insulated Flanges 52 7. Systems for Detecting Leakage and Minimising Soil Pollutio
29、n . 53 7.1 An Underground Leak Detection System . 53 7.2 Flexible Membranes . 53 7.2.1 General 53 7.2.2 Advantages and Disadvantages . 54 7.3 Double Bottoms 54 7.4 Clay Mats . 54 8. Condition Monitoring and Maintenance . 57 9. Main Conclusions and Recommendations 59 Appendix I Soil Improvement by Gr
30、ound Replacement . 61 Appendix II-1 Sand for Soil Replacement 63 Appendix II-2 Sand for Tank Foundation 65 Appendix II-3 Crushed Stone (20/40) for Crushed Stone Ring . 67 Appendix II-4 Crushed Stone (2/6) for Crushed Stone Ring . 69 Appendix III Protective Layer Product 71 Appendix IV Mixtures of Sa
31、nd and Bitumen for Tank Foundations 73 Appendix V Wet Sand for Tank Foundation Shoulders . 75 Appendix VI Examples of Tank Foundation Construction. 77 Appendix VII Typical Foundation Sectional Drawings (Figs I-1 to I-3) . 81 Appendix VIII Tank Records Flow Chart 85 Appendix IX Measures for Preventin
32、g or Containing Bottom Leakage . 87 Appendix X Evaluating and Establishing Repair Requirements 89 Appendix XI Examples of Double Bottoms . 97 Appendix XII Flow Chart to Assess Inspection and Monitoring Tasks. 101 References 103 EEMUA Publication 183 A guide for the prevention of bottom leakage from
33、storage tanks EEMUA vii Figures Figure 1 Probability of leakage from tank bottoms plotted against age 1 Figure 2 Acceptability of Tank Bottom Integrity Class . 3 Figure 3 Typical sand pad foundation 6 Figure 4 Typical detail of anchorage to concrete ring wall 7 Figure 5 Concrete raft foundations, pl
34、ain and piled . 7 Figure 6 Top view showing drain positions . 11 Figure 7 Tank foundation shoulders 13 Figure 8 Typical lap jointed bottom layout with annular plates . 17 Figure 9 Butt-welded annular bottom plates . 18 Figure 10 Lap-welded annular bottom plates 18 Figure 11 Typical lap jointed botto
35、m layout without annular plates 19 Figure 12 Deflection of tank bottom on a concrete foundation 21 Figure 13 Two types of double skin bottoms . 22 Figure 14 The letter box method . 23 Figure 15 Ingress of water by permeation and capillary action . 26 Figure 16 Corrosion at a water trap 27 Figure 17
36、Bimetallic corrosion due to copper earthing connectors 28 Figure 18 Typical example of a vacuum box 32 Figure 19 Magnetic particle inspection 33 Figure 20 Flowchart showing various inspection possibilities . 33 Figure 21 Thickness measurements on bottom sump(s) . 35 Figure 22 Principle of flux leaka
37、ge inspection method 35 Figure 23 Typical examples of some MFL tools 36 Figure 24 Typical sound distribution though metal . 37 Figure 25 Typical example of the sound propagation 37 Figure 26 Typical example of the response of sound propagation . 38 Figure 27 The Eddy Current floor scanner . 38 Figur
38、e 28 The principle of the Eddy Current technique 39 Figure 29 Signal separation between topside and underside corrosion . 39 Figure 30 The mounting of AE sensors on tank shell . 40 Figure 31 The mounting of AE sensors on an insulated tank . 40 Figure 32 Determining of origin of active corrosion by t
39、riangulation 41 Figure 33 Sound propagation induced by Long Range UT technique . 42 Figure 34 The Longe Range UT probe on the toe of the tank bottom . 43 Figure 35 Typical arrangement of the Pulsed Eddy Current probe . 43 Figure 36 Access ports for the PEC probe underneath the tank base . 44 Figure
40、37 Measuring the annular plate thickness by the PEC probe 44 Figure 38 Abstract from Figure 9-5 from API 653 . 47 Figure 39 Dealing with the limitations of fillet weld dimensions . 49 Figure 40 Tank foundation comprising compacted sand 77 Figure 41 Crushed stone ring and sand tank foundation . 77 Fi
41、gure 42 Crushed stone tank foundation 78 EEMUA Publication 183 A guide for the prevention of bottom leakage from storage tanks EEMUA viii Tables Table 1 Tank bottom integrity classification 2 Table 2 Dimensions of tank with respect to width of shoulder and height of tank foundation (without annular
42、ring) . 12 Table 3 Dimensions of tank with respect to width of shoulder and height of tank foundation (with annular ring) 12 Table 4 Minimum number of points for scan line set-up 34 Table 5 Overall and Potential Leak Data (PLD) Grades 41 EEMUA Publication 183 A guide for the prevention of bottom lea
43、kage from storage tanks EEMUA ix Foreword The prevention of ground and ground water pollution from leaking storage tanks containing oil or chemical feedstocks or products is of primary importance, particularly in areas with a large number of storage facilities. Where such facilities are near to rive
44、rs and other waterways there is an additional risk of pollution being spread and affecting a wider natural environment. Also, leakage is a financial loss to the owner. National and local authorities are becoming increasingly environmentally conscious, and various countries have introduced, or are in
45、troducing, statutory regulations aimed at minimising the risk of such pollution. The EEMUA Storage Tanks Technical Committee considered that there was a lack of guidance in this area and has therefore developed this Publication to meet that need. This Guide addresses the problem of leakage from vert
46、ical cylindrical tanks constructed of plain carbon steels and caused by loss of integrity. Such loss is almost always caused by deterioration of the tank bottom, which itself may be caused by corrosion or by deterioration of the foundation. Therefore, the guidance given is aimed exclusively at prese
47、rving the integrity of tank bottoms. Tanks of special design and those built of stainless steel or non-ferrous materials are not covered in this Guide, although many of the recommendations contained herein would be applicable to those types. Neither does the Guide cover spillages due to mal-operatio
48、n. A list of standards and other publications referred to in the text is given in the References at the back of the Publication. Note on Terminology The terms tank system and stored product are used in the text. Tank system means the entire tank and its foundation. Stored product refers to whatever
49、oil or chemical is stored in the tank, including feedstocks.EEMUA Publication 183 A guide for the prevention of bottom leakage from storage tanks EEMUA x EEMUA Publication 183 A guide for the prevention of bottom leakage from storage tanks EEMUA 1 1. Introduction and Scope 1.1 Background Experience has shown that the bottoms of vertical cylindrical steel storage tanks used for oil and chemical products are the most vulnerable part of the structure. It is obvious that the risk of bottom leakage increases with
