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Structural Design of Air and Gas Ducts for Power Stations and Industrial Boiler Applications, 2020
- Structural Design of Air and Gas Ducts for Power Stations and Industrial Boiler Applications
- Contents
- PREFACE
- Acknowledgments
- Chapter 1: Introduction [Go to Page]
- 1.1 STATEMENT OF INTENT AND EXPECTED USE OF THIS BOOK
- 1.2 LIMITATIONS AND SCOPE OF THIS BOOK [Go to Page]
- 1.2.1 Scope
- 1.2.2 Limitations
- 1.2.3 Application of Building Codes and Design Codes
- 1.3 DUCTWORK SYSTEMS DESCRIPTIONS [Go to Page]
- 1.3.1 Ductwork Systems
- 1.3.2 Air Ducts
- 1.3.3 Flue-Gas Ducts or Flues
- 1.3.4 Typical Pressures and Temperatures
- 1.4 GLOSSARY/DEFINITIONS [Go to Page]
- 1.4.1 Ductwork
- 1.4.2 Duct Supports
- 1.4.3 Duct Appurtenances
- 1.4.4 Internal Flow Distribution Devices
- 1.4.5 Duct Service Conditions
- 1.4.6 Duct Conveyances
- 1.5 DESCRIPTIONS OF MAJOR DUCTWORK EQUIPMENT
- 1.6 DUCTWORK ACCESSORIES
- References
- Chapter 2: Ductwork Arrangement and Behavior [Go to Page]
- 2.1 OVERVIEW [Go to Page]
- 2.1.1 Flow Considerations
- 2.1.2 Design Process
- 2.2 INTERFACES WITH EQUIPMENT [Go to Page]
- 2.2.1 Isolation of Major Equipment from the Ductwork
- 2.2.2 Fans
- 2.2.3 Equipment Removal
- 2.2.4 Dampers
- 2.2.5 Flue-Gas Monitoring: Instruments
- 2.2.6 Access Doors
- 2.3 THERMAL EXPANSION [Go to Page]
- 2.3.1 Expansion Joints
- 2.3.2 Toggle Duct Sections
- 2.3.3 Location of Anchors and Guides
- 2.3.4 Slide Bearing Plates
- 2.3.5 Clearances
- 2.3.6 Support Eccentricities
- 2.3.7 Attachment of Cold Items to Ducts
- 2.4 SUPPORTS [Go to Page]
- 2.4.1 Support Locations
- 2.4.2 Structural Determinacy of Ductwork
- 2.4.3 Hangers versus Bottom Supports
- 2.4.4 Spring Hangers versus Rigid Hangers
- 2.4.5 Support Elevations
- 2.4.6 Support Structure Stiffness
- 2.4.7 Ductwork Stiffness
- 2.4.8 Supporting Ducts from Equipment
- 2.4.9 Retrofitting Ductwork
- 2.5 DUCT GEOMETRIES [Go to Page]
- 2.5.1 Basic Ductwork Configuration
- 2.5.2 Rectangular Ducts
- 2.5.3 Circular Ducts
- 2.5.4 Hoppers
- 2.5.5 Transition Duct Sections
- 2.6 INTERNAL TRUSSES AND STRUTS [Go to Page]
- 2.6.1 Location and Layout
- 2.6.2 Vibration Considerations
- 2.6.3 Erosion Considerations
- 2.7 EFFECTS OF THE ARRANGEMENT ON LOADS [Go to Page]
- 2.7.1 Static Pressure
- 2.7.2 Dynamic Pressure
- 2.7.3 Vibrations
- 2.7.4 Ash Deposition
- 2.7.5 Metal Expansion Joints
- 2.7.6 Thermal Gradients
- References
- Chapter 3: Structural Material: Selection, Application, and Properties [Go to Page]
- 3.1 INTRODUCTION
- 3.2 AVAILABILITY OF MATERIALS
- 3.3 MATERIAL PROPERTIES [Go to Page]
- 3.3.1 Coefficient of Thermal Expansion
- 3.3.2 Modulus of Elasticity
- 3.3.3 Yield Strength
- 3.3.4 Tensile Strength
- 3.3.5 Creep and Creep-Rupture
- 3.3.6 Temper Embrittlement and Graphitization
- 3.4 MATERIAL SELECTION [Go to Page]
- 3.4.1 Low-Temperature and Medium-Temperature Ducts
- 3.4.2 High-Temperature Ducts
- 3.4.3 Wet Ducts
- 3.5 BOLTS
- 3.6 WELDING ELECTRODES
- 3.7 DUCTWORK PROTECTION [Go to Page]
- 3.7.1 Corrosion Allowances
- 3.7.2 Coatings
- 3.7.3 Liners
- 3.8 HANGER ELEMENTS
- References
- Chapter 4 : Service Conditions and Design Loads [Go to Page]
- 4.1 SERVICE CONDITIONS [Go to Page]
- 4.1.1 Site Location
- 4.1.2 Indoor versus Outdoor Service
- 4.1.3 Mechanical Performance Considerations
- 4.1.4 Nature of the Media Flowing through Ducts
- 4.1.5 Operating Conditions
- 4.1.6 Excursion and Transient Conditions
- 4.1.7 Insulation and Lagging Requirements
- 4.1.8 Corrosion and Erosion Allowances
- 4.2 DESIGN LOADS [Go to Page]
- 4.2.1 Dead Load
- 4.2.2 Live Load
- 4.2.3 Environmental Loads
- 4.2.4 Pressure Loads
- 4.2.5 Ash Loads
- 4.2.6 System-Related Loads
- 4.2.7 Thermal Gradient Loads
- 4.2.8 Construction Loads
- REFERENCES
- Chapter 5 : Load Combinations and Associated Design Strengths [Go to Page]
- 5.2 STRESS-BASED VERSUS STRENGTH-BASED DESIGN
- 5.3 STRENGTH AT TEMPERATURES WITHIN THE CREEP RANGE
- 5.4 LOAD DEFINITIONS
- 5.5 DEVELOPING LOAD COMBINATIONS FOR DUCTWORK DESIGN [Go to Page]
- 5.5.1 General Requirements
- 5.5.2 LRFD Load Combinations That Include Loads Not Specified in ASCE 7
- 5.5.3 ASD Load Combinations That Include Loads Not Specified in ASCE 7
- 5.5.4 Considerations for Load Combinations with Excursion Temperature
- 5.5.5 Other Considerations in Developing and Using the Load Combinations
- 5.6 LOAD COMBINATIONS FOR ALLOWABLE-STRENGTH DESIGN [Go to Page]
- 5.6.1 Load Combinations at Ambient Temperature (Off-Line Condition)
- 5.6.2 Load Combinations at Operating Temperatures below Creep Range
- 5.6.3 Long-Duration Load Combination at Temperatures within the Creep Range
- 5.6.4 Short-Duration Load Combinations at Temperatures within the Creep Range
- 5.6.5 Load Combination at Excursion Temperature
- 5.6.6 Thermal Gradient Load Combinations at Operating Temperature
- 5.7 LOAD COMBINATIONS FOR LOAD AND RESISTANCE FACTOR DESIGN [Go to Page]
- 5.7.1 Load Combinations at Ambient Temperature (Off-Line Condition)
- 5.7.2 Load Combinations at Operating Temperatures below Creep Range
- 5.7.3 Long-Duration Load Combination at Temperatures within the Creep Range
- 5.7.4 Short-Duration Load Combinations at Temperatures within the Creep Range
- 5.7.5 Load Combination at Excursion Temperature
- 5.7.6 Thermal Gradient Load Combinations at Operating Temperature
- References
- Chapter 6 : Ductwork Global Structural Analysis [Go to Page]
- 6.1 INTRODUCTION
- 6.2 GLOBAL APPROACH [Go to Page]
- 6.2.1 Decoupling of Supports and Ductwork
- 6.2.2 Load Paths
- 6.2.3 Load Interactions
- 6.2.4 Classical Methods
- 6.2.5 Computer Models
- 6.2.6 Finite Element Analysis
- 6.3 STRUCTURAL MODEL CONSIDERATIONS [Go to Page]
- 6.3.1 Support Structures
- 6.3.2 Rectangular Ductwork
- 6.3.3 Circular Ductwork
- 6.3.4 Modeling Strategy
- 6.3.5 Interface Boundary Conditions
- 6.3.6 Load Path Assessment
- 6.3.7 Load Development and Application
- 6.3.8 Model Validation
- 6.3.9 Member Forces and Reactions
- 6.3.10 Displacements
- References
- Chapter 7: Plate Design [Go to Page]
- 7.1 INTRODUCTION [Go to Page]
- 7.1.1 Global Behavior
- 7.1.2 Duct Support Scheme Effects on Plate Forces
- 7.2 RECTANGULAR DUCTWORK PLATE DESIGN [Go to Page]
- 7.2.1 Typical Plate Thickness and Stiffener Spacing
- 7.2.2 Stiffener Contributory Areas and Plate Analysis
- 7.2.3 Plate Analysis Deflection Theories
- 7.2.4 Secondary versus Primary Stresses
- 7.2.5 Combined Local and Global Interaction
- 7.3 CIRCULAR DUCTWORK PLATE DESIGN [Go to Page]
- 7.3.1 Designing for Buckling
- 7.3.2 Longitudinal Stress
- 7.3.3 Shell Hoop Stress
- 7.3.4 Tangential Shear Stress
- 7.3.5 Factors of Safety
- 7.3.6 Material Handling Considerations
- 7.4 OTHER CONSIDERATIONS [Go to Page]
- 7.4.1 Fatigue, Endurance Limits, and Crack Control
- 7.4.2 Solutions to Problems
- References
- Chapter 8: Structural Element Design [Go to Page]
- 8.1 GENERAL CONSIDERATIONS
- 8.2 RECTANGULAR DUCTS [Go to Page]
- 8.2.1 Stiffener Layout
- 8.2.2 Stiffener Design
- 8.2.3 Stiffener End Connections
- 8.2.4 Corner Configurations
- 8.3 CIRCULAR DUCTS [Go to Page]
- 8.3.1 Ring Stiffeners
- 8.3.2 Internal Struts
- 8.4 INTERNAL TRUSSES AND STRUTS [Go to Page]
- 8.4.1 Analysis Methods
- 8.4.2 Truss Element Design
- 8.4.3 Truss Member End Connections
- 8.5 DUCT SUPPORTS
- 8.6 LATERAL EXTERNAL TIE ELEMENTS
- 8.7 SERVICEABILITY AND DEFLECTION LIMITS [Go to Page]
- 8.7.1 Duct Plate and Stiffeners Serviceability Criteria
- 8.7.2 Internal Truss Serviceability Criteria
- References
- Chapter 9: Structural Design of Flow Distribution Devices [Go to Page]
- 9.1 FUNCTION OF FLOW DISTRIBUTION DEVICES
- 9.2 FLOW DEVICES FOR PROCESS EQUIPMENT
- 9.3 FLOW LAYOUT AND STRUCTURAL CONSIDERATIONS [Go to Page]
- 9.3.1 Flow Resistance
- 9.3.2 Physical Arrangement Considerations
- 9.4 SUPPORT CONSIDERATIONS
- 9.5 STRUCTURAL ANALYSIS [Go to Page]
- 9.5.1 Stiffness Requirements
- 9.5.2 Dynamic Loads
- 9.5.3 Static Loads
- 9.5.4 Minimum Loads
- 9.6 STRUCTURAL DESIGN [Go to Page]
- 9.6.1 Local Design Requirements
- 9.6.2 Global Design Requirements
- References
- Chapter 10: Drawing, Fabrication, and Construction: Techniques and Considerations [Go to Page]
- 10.1 GENERAL CONSIDERATIONS [Go to Page]
- 10.1.1 Shipping Modes and Dimension Considerations
- 10.1.2 Construction Economy
- 10.1.3 Field Splices
- 10.2 DRAWINGS AND SPECIFICATIONS [Go to Page]
- 10.2.1 Drawing Preparation
- 10.2.2 Fabrication Specification
- 10.2.3 Erection Specification
- 10.3 FABRICATION [Go to Page]
- 10.3.1 Plate Fit-Up
- 10.3.2 Fit-Up of Stiffeners, Flanges, and Attachments
- 10.3.3 Assembly of Duct Sections
- 10.4 WELDING [Go to Page]
- 10.4.1 Welding Codes and Standards
- 10.4.2 Types of Welding Processes
- 10.4.3 Welding Electrodes
- 10.5 SHOP INSPECTION
- 10.6 SURFACE PREPARATION
- 10.7 HANDLING AND SHIPPING [Go to Page]
- 10.7.1 Piece Marking
- 10.7.2 Lifting Lugs
- 10.7.3 Temporary Bracing
- 10.7.4 Loading, Receiving, and Unloading
- 10.8 ERECTION [Go to Page]
- 10.8.1 Erection Sequencing
- 10.8.2 Special Erection Considerations
- References
- Chapter 11: Insulation and Lagging [Go to Page]
- 11.1 INTRODUCTION
- 11.2 PURPOSE OF INSULATION AND LAGGING [Go to Page]
- 11.2.1 Thermal Efficiency
- 11.2.2 Corrosion Prevention
- 11.2.3 Personnel Protection
- 11.2.4 Protection against Water
- 11.2.5 Reduction of Steel Temperature in Very Hot Ducts
- 11.2.6 Sound Attenuation
- 11.3 TYPES OF INSULATION AND LAGGING [Go to Page]
- 11.3.1 Insulation
- 11.3.2 Lagging
- 11.3.3 Subgirts and Standoffs
- 11.4 EFFECTS OF INSULATION AND LAGGING ON THE STRUCTURAL DESIGN OF DUCTS [Go to Page]
- 11.4.1 Layout Considerations
- 11.4.2 Duct Design Considerations
- 11.4.3 Dead Load Determination
- 11.4.4 Wind Load Determination
- 11.5 METHODS OF INSTALLATION AND QUALITY OF THE WORK [Go to Page]
- 11.5.1 Construction Details
- 11.5.2 Installation Methods
- 11.6 CONSTRUCTION DETAILS [Go to Page]
- 11.6.1 Insulation at Expansion Joints
- 11.6.2 Insulation around Hoppers
- 11.6.3 Insulation around Duct Appurtenances
- 11.6.4 Attachment of Lagging
- 11.6.5 Attachment of Subgirts
- References
- Chapter 12: Maintenance Examination of Existing Duct Systems [Go to Page]
- 12.1 FACTORS THAT INFLUENCE THE NEED FOR STRUCTURAL EXAMINATIONS [Go to Page]
- 12.1.1 Original Design Basis versus Operating Basis
- 12.1.2 Exposure to Weather, Chemical, and Thermal Conditions
- 12.1.3 Duct Erosion
- 12.1.4 Operations Records
- 12.1.5 Cumulative Effect of Exposure and Operating Conditions
- 12.1.6 Ensuring Structural Integrity
- 12.2 FIELD EXAMINATION TECHNIQUES [Go to Page]
- 12.2.1 Preparation and Planning
- 12.2.2 Safety Considerations
- 12.2.3 Equipment
- 12.2.4 Identification of Critical Duct Sections
- 12.2.5 Exterior Walkdowns
- 12.2.6 Interior Walkdowns
- 12.2.7 Thickness Measurements
- 12.2.8 Temperature Monitoring
- 12.2.9 Displacement Measuring
- 12.2.10 Infrared Survey
- 12.2.11 Laboratory Test Samples
- 12.2.12 Documentation
- 12.3 POTENTIAL DAMAGE AREAS [Go to Page]
- 12.3.1 Indicators
- 12.3.2 Structural Elements
- 12.4 EXAMINATION DATA, EVALUATION, AND DISPOSITION [Go to Page]
- 12.4.1 Examination Data Assimilation
- 12.4.2 Repairs
- 12.4.3 Evaluation and Disposition Considerations
- 12.4.4 Final Report
- References
- Chapter 13: Reinforcement of Existing Ductwork [Go to Page]
- 13.1 INTRODUCTION
- 13.2 EVALUATION OF EXISTING DUCTWORK
- 13.3 DUCTWORK WALKDOWN
- 13.4 DUCTWORK MODIFICATION
- 13.5 REINFORCEMENT [Go to Page]
- 13.5.1 General
- 13.5.2 Duct Plate
- 13.5.3 Duct Stiffeners
- 13.5.4 Internal Trusses
- 13.5.5 Support Stubs
- 13.5.6 Support Assemblies
- 13.6 OTHER CONSIDERATIONS [Go to Page]
- 13.6.1 Replacement of Metallic Expansion Joints
- 13.6.2 Higher Flow and Flow Velocities [Go to Page]
- References
- Index [Go to Page]