EEMUA PUB NO 159-2017 Above ground flat bottomed storage tanks A guide to inspection maintenance and repair (Edition 5).pdf

1、THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION This publication has been made available for release by IHS NOT FOR RESALE Any organisation that is a substantial user or substantial purchaser of engineering products may apply to become a member of EEMUA. EEMUA Copyright 2017 The Engineerin

2、g Equipment and Materials Users Association Above ground flat bottomed storage tanks: A guide to inspection maintenance and repair Publication 159 Edition 5 Copyright 2017 The Engineering Equipment and Materials Users Association A company limited by guarantee. Registered in England. Company number

3、477838. ISBN 978-0-85931-218-9 Imprint reference 09-2017 First published 09-2017 Registered and Trading Address: EEMUA, Second Floor, 16 Black Friars Lane, London EC4V 6EB Telephone: +44 (0)20 7488 0801 Email: saleseemua.org Website: www.eemua.orgII Above ground flat bottomed storage tanks: A guide

4、to inspection maintenance and repair Publication 159 EEMUA Copyright 2017 The Engineering Equipment 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 i

5、s responsible for the policies, financing, membership, and strategy of the Association. Any organisation that is a substantial user or purchaser of engineering products may apply to become a member of EEMUA. Membership is subject to the approval of Council. EEMUA Aims EEMUA aims to improve the safet

6、y, environmental and operating performance of industrial facilities in the most cost-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 engine

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12、ns website, including details of on-line shopping facilities. To enquire about corporate Membership, write to enquirieseemua.org or call +44 (0)20 7488 0801. Engineering Equipment and Materials Users AssociationIII Above ground flat bottomed storage tanks: A guide to inspection maintenance and repai

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18、g 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 when making use of this Publication is asked to notify EEMUA without delay so that the matter may

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21、idered by the relevant EEMUA Technical Committees and may be incorporated in future editions of this Publication. New editions are publicised on the EEMUA website.About this PublicationIV Above ground flat bottomed storage tanks: A guide to inspection maintenance and repair Publication 159 EEMUA Cop

22、yright 2017 The Engineering Equipment and Materials Users Association Contents 1 Introduction and scope 1 1.1 Introduction 1 1.2 Scope 2 1.3 Codes and history 2 1.4 Definitions and Abbreviations .3 2 Tanks and their components: Terminology and materials of construction .5 2.1 Tank components5 2.2 Gl

23、ossary of terms 7 2.3 Types of storage tanks 9 2.3.1 Standard atmospheric storage tanks.9 2.4 Materials . 16 2.4.1 Ambient conventional storage tanks .16 3 Degradation mechanisms and failure modes . 17 3.1 General corrosion . 17 3.2 Tank settlement and consequential problems 18 3.3 Structural failur

24、e and/or failure of tank components/appendages . 18 3.4 Low Cycle Fatigue failure mechanism 19 3.4.1 Storage tanks can be subject to cyclic stresses 19 3.4.2 Bottom-to-shell connection 20 3.4.3 Floating roofs .20 3.4.4 Articulated pipe of roof drain systems.20 3.5 Combination of degradation mechanis

25、ms and other influences. 20 3.6 Microbial Induced Corrosion (MIC) .21 4 Corrosion of tanks .23 4.1 General . 23 4.2 Types of corrosion 23 4.2.1 Uniform corrosion .24 4.2.2 Pitting corrosion .24 4.2.3 Crevice / under deposit corrosion25 4.2.4 Galvanic corrosion .27 4.2.5 Stress corrosion cracking (SC

26、C) 28 4.2.6 Microbiologically induced corrosion (MIC) .28V Above ground flat bottomed storage tanks: A guide to inspection maintenance and repair Publication 159 EEMUA Copyright 2017 The Engineering Equipment and Materials Users Association 4.3 Corrosion rates . 29 4.4 Bottom plates . 31 4.4.1 Failu

27、re modes 31 4.4.2 Bottom plate soil side corrosion 31 4.4.3 Bottom plate product side corrosion . 33 4.5 Shell plates (internal and external) .34 4.6 Roof plates 37 4.6.1 Fixed roofs including roof support structure . 37 4.6.2 Floating roofs including supporting legs .39 4.7 Corrosion Under Insulati

28、on (CUI) . 40 4.8 Corrosion of stubs and appendages .44 5 General inspection techniques and interpretation of inspection data . 45 5.1 References 45 5.1.1 Inspection and maintenance 45 5.1.2 Assessing the tank norm or standard .49 5.1.3 Fit-for-purpose analysis of storage tanks: 52 5.2 Inspection .

29、52 5.2.1 General . 52 5.2.2 Operator observations 54 5.2.3 Routine and detailed visual inspections . 55 5.2.4 In-service inspection (non-intrusive) 56 5.2.5 Out-of-service inspection 57 5.2.6 Safety considerations during inspection 58 5.3 Ultrasonic thickness measurements 59 5.3.1 General .59 5.3.2

30、Phased Array Ultrasonic Testing (PA UT).59 5.3.3 Alternating Current Field Measurement (ACFM) 61 5.3.4 Tank shell measurement 63 5.3.5 Tank bottom measurement . 65 5.3.6 Tank roof measurement .67 5.3.7 Measurement of nozzles and manhole neck plates . 69 5.4 Evaluation of shell inspection data .71 6

31、Tank foundations 75 6.1 General . 75 6.1.1 Introduction 75 6.1.2 Failure modes of tank foundations 76 6.2 Soil settlement . 76 6.2.1 Settlement under loads 76 6.2.2 Consolidated settlement .76VI Above ground flat bottomed storage tanks: A guide to inspection maintenance and repair Publication 159 EE

32、MUA Copyright 2017 The Engineering Equipment and Materials Users Association 6.3 Effects of soil settlement 77 6.3.1 Even (uniform) settlement 77 6.3.2 Tank shell settlement into the foundation 77 6.3.3 Difference in soil settlement between centre and periphery of the tank . 78 6.3.4 Uneven settleme

33、nt .81 6.3.5 Edge settlement .82 6.3.6 Planar tilt . 84 6.3.7 Differential shell settlement around circumference 84 6.3.8 Evaluation and measurements for shell out of roundness 86 6.4 Leakage 86 6.5 Maximum tolerances and limits for settlement and out-of-verticality of tank shell 87 6.5.1 Planar til

34、t/out-of-verticality 87 6.5.2 Edge Settlement .91 6.5.3 Differential settlement 92 6.5.4 Sagging/centre-to-edge bottom settlement 95 6.5.5 Bottom ripples .96 6.6 Re-levelling of tank foundations 96 6.7 Tank lifting operations .97 6.7.1 Preliminaries .97 6.7.2 Tank lifting .98 6.7.3 Wind loading 98 6

35、.7.4 Safety measures against wind damage 99 6.8 Repair/modification methods - some typical examples . 100 7 Tank bottoms (with or without annular plates) 101 7.1 General 101 7.2 Introduction 101 7.3 Determination of floor thickness and condition 102 7.4 Rejection limits 105 7.4.1 Floor area . 105 7.

36、4.2 Annular area . 108 7.4.3 Annular projection . 108 7.5 Bulges and depressions in tank bottom plates 113 7.6 Cathodic protection . 114 7.7 Repair/modification methods - some typical examples . 114 8 Tank shells .115 8.1 General 115 8.2 Determination of effective shell plate thickness and condition

37、 . 116 8.3 Rejection limits for shell plates 117 8.3.1 Liquid Load and vapour pressure 117 8.3.2 Wind and vacuum loads . 120VII Above ground flat bottomed storage tanks: A guide to inspection maintenance and repair Publication 159 EEMUA Copyright 2017 The Engineering Equipment and Materials Users As

38、sociation 8.3.3 Roof loads 122 8.3.4 Pit corrosion assessment 123 8.4 Minimum thickness calculations for riveted tank shells. . 123 8.5 Top wind girder and intermediate wind stiffeners. 124 8.5.1 Shell top wind girders 124 8.5.2 Intermediate wind stiffeners 125 8.6 Buckling problems of tank shells a

39、nd top wind girders 128 8.6.1 Buckling problems of tank shells . 128 8.6.2 Shell top wind girders 131 8.7 Manholes, nozzles and connecting piping . 132 8.7.1 Shell manholes and nozzles . 132 8.7.2 Connecting piping . 133 8.7.3 Rejection limits shell nozzles 134 8.8 Clean-out doors and openings 135 8

40、.8.1 Clean-out doors . 135 8.8.2 Clean-out openings . 136 8.9 Earthing . 137 8.10 Repair/modification methods - some typical examples. 138 9 Tank roofs - general 141 9.1 Introduction 141 9.2 Determination of roof plate thickness and condition 141 10 Fixed roofs (cone roofs and dome roofs) .143 10.1

41、General 143 10.2 Roof manholes and nozzles 144 10.3 Roof vents (ventilation of tanks) and emergency relief vents . 145 10.3.1 The functioning of roof vents . 145 10.3.2 Venting requirements for fixed roof tanks . 146 10.3.3 Inspection and maintenance of roof vents . 148 10.3.4 Possible ventilation p

42、roblems 152 10.3.5 Flame arresters 154 10.3.6 Pressure test of the fixed roof . 155 10.3.7 Temporary closure of openings in open vents or pressurevacuum valvesduring operation 156 10.3.8 Protection against static electricity and lightning 156 10.4 Column supported roofs 156 10.4.1 Internal Inspectio

43、n and repair . 157 10.4.2 Tank jacking or lifting . 157 10.4.3 Column design 158 10.5 Membrane (self-supporting) roof 158VIII Above ground flat bottomed storage tanks: A guide to inspection maintenance and repair Publication 159 EEMUA Copyright 2017 The Engineering Equipment and Materials Users Asso

44、ciation 10.6 Degradation limits for fixed roofs 158 10.6.1 Supported fixed roof 159 10.6.2 Roof supporting structure . 161 10.6.3 Self-supporting fixed roof . 161 10.7 Fitness for service assessment . 161 10.8 Internal Floating Covers (IFCs) . 163 10.9 Repair/modification methods . 166 11 Floating r

45、oofs 169 11.1 Types 169 11.1.1 General . 169 11.1.2 Pontoon type floating roofs . 170 11.1.3 Double-deck floating roofs. 171 11.1.4 Special roofs such as buoy type and radially reinforced roofs . 172 11.2 Degradation limits 173 11.2.1 General corrosion . 173 11.2.2 Pit corrosion 174 11.3 Equipment o

46、n External floating roofs . 175 11.3.1 Roof drains . 175 11.3.2 Floating roof seals 180 11.3.3 Roof support legs . 191 11.3.4 Floating roof venting . 193 11.3.5 Rolling ladders . 194 11.3.6 Earthing of floating roofs . 196 11.4 Guidelines for the operation of floating roofs 196 11.4.1 Introduction 1

47、96 11.4.2 Before the roof is taken into service 196 11.4.3 During the first month of operation . 196 11.4.4 During operation 197 11.4.5 Before landing the roof . 198 11.4.6 Roof standing on its supports . 198 11.4.7 Recommended filling rates for floating roof tanks . 198 11.4.8 Ballooning of single

48、-deck floating roof . 199 11.5 Possible problems with EFR buoyancy . 201 11.5.1 Leaking pontoon compartments 201 11.5.2 Cracking in centre deck due to wind loading 201 11.5.3 Out-of-roundness tolerances 201 11.6 Repair/modification methods . 203 11.6.1 Overplating 204IX Above ground flat bottomed st

49、orage tanks: A guide to inspection maintenance and repair Publication 159 EEMUA Copyright 2017 The Engineering Equipment and Materials Users Association 11.7 Snow load on EFR . 204 11.7.1 Inspection history 204 11.7.2 Removal of the snow . 204 11.7.3 Operation of the tank 205 11.8 Aluminium dome roofs . 205 12 Tank appendages 207 12.1 Shell and roof nozzles . 207 12.2 Floating suction lines 209 12.2.1 Design. 209 12.2.2 Operational experiences 209 12.2.3 Inspection . 210 12.3 Ladders, stairways, platforms/railings and lighting . 210 12.4 Side entry mixe