Pipe Stress Engineering

495 Pages·2009·41.31 MB·English

by  Liang-Chuan Peng

PiPe StreSS
engineering
by
Liang-Chuan (L.C.) Peng and
tsen-Loong (Alvin) Peng
Peng engineering, Houston, texas, USA

CONTENTS
Acknowledgments.........................................................................................................................................xi
Preface..............................................................................................................................................xiii
Nomenclature....................................................................................................................................xv
Chapter.1
Introduction........................................................................................................................................1
1.1. Scope.of.Pipe.Stress.Analysis....................................................................................................2
1.2. Piping.Components.and.Connecting.Equipment......................................................................4
1.3. Modes.of.Failure.......................................................................................................................9
1.3.1. Static.Stress.Rupture......................................................................................................9
1.3.2. Fatigue.Failure.............................................................................................................12
1.3.3. Creep.Rupture.............................................................................................................14
1.3.4. Stability.Failure............................................................................................................17
1.3.5. Miscellaneous.Modes.of.Failure..................................................................................18
1.4. Piping.Codes...........................................................................................................................19
1.5. Industry.Practice.....................................................................................................................22
1.5.1. Load.Cases...................................................................................................................23
1.5.2. Local.Support.Stresses.................................................................................................24
1.5.3. Local.Thermal.Stresses................................................................................................24
1.5.4. Pressure.Effect.on.Flexibility.......................................................................................25
1.5.5. Stress.Intensification.for.Sustained.Loads...................................................................25
1.5.6. Support.Friction..........................................................................................................25
1.5.7. Guide.and.Stop.Gaps...................................................................................................26
1.5.8. Anchor.and.Restraint.Stiffness....................................................................................26
1.5.9. Small.Piping.................................................................................................................26
1.6. Design.Specification...............................................................................................................26
1.6.1. Owner’s.Design.Specification......................................................................................26
1.6.2. Project.Specification....................................................................................................28
1.7. Plant.Walk-down....................................................................................................................30
Chapter.2
Strength.of.Materials.Basics..............................................................................................................33
2.1. Tensile.Strength......................................................................................................................33
2.1.1. Modulus.of.Elasticity...................................................................................................34
2.1.2. Proportional.Limit.......................................................................................................34
2.1.3. Yield.Strength,.S .........................................................................................................35
y
2.1.4. Ultimate.Strength,.S ...................................................................................................35
u
2.1.5. Stresses.at.Skewed.Plane.............................................................................................35
2.1.6. Maximum.Shear.Stress,.S ......................................................................................36
s,max
2.1.7. Principal.Stresses.........................................................................................................36
2.2. Elastic.Relationship.of.Stress.and.Strain................................................................................36
2.2.1. Poisson’s.Ratio............................................................................................................37
2.2.2. Shear.Strain.and.Modulus.of.Rigidity..........................................................................38
iv. Contents
2.3. Static.Equilibrium...................................................................................................................38
2.3.1. Free-Body.Diagram.....................................................................................................39
2.3.2. Static.Equilibrium........................................................................................................40
2.4. Stresses.due.to.Moments.........................................................................................................40
2.4.1. Stresses.due.to.Bending.Moments...............................................................................40
2.4.2. Moment.of.Inertia........................................................................................................42
2.4.3. Polar.Moment.of.Inertia..............................................................................................42
2.4.4. Moment.of.Inertia.for.Circular.Cross-Sections...........................................................43
2.4.5. Stresses.due.to.Torsion.Moment.................................................................................43
2.5. Stresses.in.Pipes......................................................................................................................45
2.5.1. Stresses.due.to.Internal.Pressure.................................................................................45
2.5.2. Stresses.due.to.Forces.and.Moments...........................................................................47
2.6. Evaluation.of.Multi-Dimensional.Stresses..............................................................................49
2.6.1. General.Two-Dimensional.Stress.Field.......................................................................49
2.6.2. Mohr’s.Circle.for.Combined.Stresses..........................................................................51
2.6.3. Theories.of.Failure.......................................................................................................52
2.6.4. Stress.Intensity.(Tresca.Stress)....................................................................................52
2.6.5. Effective.Stress.(von.Mises.Stress)...............................................................................53
2.7. Basic.Beam.Formulas.............................................................................................................53
2.7.1. Guided.Cantilever........................................................................................................55
2.8. Analysis.of.Piping.Assembly...................................................................................................55
2.8.1. Finite.Element.............................................................................................................56
2.8.2. Data.Points.and.Node.Points......................................................................................57
2.8.3. Piping.Assembly..........................................................................................................58
Chapter.3
Thermal.Expansion.and.Piping.Flexibility........................................................................................61
3.1. Thermal.Expansion.Force.and.Stress.....................................................................................61
3.1.1. Ideal.Anchor.Evaluation..............................................................................................61
3.1.2. The.Real.Anchor..........................................................................................................62
3.2. Methods.of.Providing.Flexibility............................................................................................63
3.2.1. Estimating.Leg.Length.Required.................................................................................63
3.2.2. Inherent.Flexibility......................................................................................................65
3.2.3. Caution.Regarding.Quick.Check.Formulas.................................................................65
3.2.4. Wall.Thickness.and.Thermal.Expansion.Stress...........................................................66
3.3. Self-Limiting.Stress.................................................................................................................66
3.3.1. Elastic.Equivalent.Stress..............................................................................................67
3.4. Stress.Intensification.and.Flexibility.Factors..........................................................................67
3.4.1. Ovalization.of.Curved.Pipes........................................................................................68
3.4.2. Code.SIFs....................................................................................................................69
3.5. Allowable.Thermal.Expansion.Stress.Range..........................................................................71
3.6. Cold.Spring.............................................................................................................................76
3.6.1. Cold.Spring.Gap..........................................................................................................77
3.6.2. Location.of.Cold.Spring.Gap.......................................................................................78
3.6.3. Cold.Spring.Procedure.................................................................................................78
3.6.4. Multi-Branched.System...............................................................................................79
3.6.5. Analysis.of.Cold.Sprung.Piping.System.......................................................................79
3.7. Pressure.Effects.on.Piping.Flexibility.....................................................................................80
3.7.1. Pressure.Elongation.....................................................................................................80
3.7.2. Potential.Twisting.at.Bends.........................................................................................81
Contents. v
3.7.3. Pressure.Elongation.Is.Self-Limiting.Load..................................................................82
3.7.4. Pressure.Effect.on.Bend.Flexibility.and.SIFs...............................................................82
3.8. General.Procedure.of.Piping.Flexibility.Analysis...................................................................83
3.8.1. Operating.Modes.........................................................................................................83
3.8.2. Anchor.Movements.....................................................................................................84
3.8.3. Assignments.of.Operating.Values................................................................................84
3.8.4. Handling.of.Piping.Components..................................................................................85
3.8.5. The.Analysis................................................................................................................86
3.9. Problems.With.Excessive.Flexibility.......................................................................................86
3.9.1. Problems.Associated.With.Excessive.Flexibility.........................................................88
3.10. Field.Proven.Systems..............................................................................................................88
Chapter.4
Code.Stress.Requirements.................................................................................................................91
4.1. “Design”.Chapter.of.the.Piping.Codes...................................................................................91
4.2. Loadings.to.be.Considered.....................................................................................................92
4.2.1. Pressure.......................................................................................................................93
4.2.2. Temperature................................................................................................................93
4.2.3. Weight.Effects..............................................................................................................95
4.2.4. Wind.Load...................................................................................................................95
4.2.5. Earthquake...................................................................................................................96
4.2.6. Dynamic.Fluid.Loads..................................................................................................96
4.2.7. Harmonic.Anchor.Displacement.Loads......................................................................98
4.2.8. Passive.Loads...............................................................................................................98
4.3. Basic.Allowable.Stresses.........................................................................................................98
4.3.1. Bases.for.Establishing.Allowable.Stresses....................................................................98
4.3.2. Code.Allowable.Stress.Tables......................................................................................99
4.3.3. Weld.Strength.Reduction.Factor...............................................................................100
4.4. Pressure.Design....................................................................................................................101
4.4.1. Straight.Pipe..............................................................................................................102
4.4.2. Curved.Segment.of.Pipe.............................................................................................104
4.4.3. Miter.Bends...............................................................................................................106
4.4.4. Branch.Connections..................................................................................................109
4.4.5. Pressure.Design.for.Other.Components....................................................................113
4.5. Stresses.of.Piping.Components.............................................................................................113
4.5.1. Calculations.of.Component.Stresses..........................................................................113
4.5.2. Sustained.Stresses......................................................................................................117
4.5.3. Occasional.Stresses....................................................................................................119
4.5.4. Thermal.Expansion.and.Displacement.Stress.Range.................................................121
4.5.5. Code.Stress.Compliance.Report................................................................................124
4.6. Class.1.Nuclear.Piping..........................................................................................................125
Chapter.5
Discontinuity.Stresses......................................................................................................................133
5.1. Differential.Equation.of.the.Beam.Deflection.Curve............................................................133
5.2. Infinite.Beam.on.Elastic.Foundation.With.Concentrated.Load............................................135
5.3. Semi-Infinite.Beam.on.Elastic.Foundation...........................................................................138
5.4. Application.of.Beam.on.Elastic.Foundation.to.Cylindrical.Shells........................................139
5.5. Effective.Widths....................................................................................................................141
5.6. Choking.Model.....................................................................................................................142
vi. Contents
5.7. Stresses.at.Junctions.Between.Dissimilar.Materials.............................................................143
5.7.1. Uniform.Pipes.With.Similar.Modulus.of.Elasticity....................................................144
5.7.2. A.Pipe.Connected.to.a.Rigid.Section.........................................................................146
5.8. Vessel.Shell.Rotation............................................................................................................147
Chapter.6
Pipe.Supports.and.Restraints..........................................................................................................151
6.1. Device.Terminology.and.Basic.Functions............................................................................151
6.2. Support.Spacing....................................................................................................................157
6.3. Analysis.of.Piping.Systems.Resting.on.Supports..................................................................159
6.4. Variable.Spring.and.Constant.Effort.Supports......................................................................162
6.4.1. Variable.Spring.Hanger.Selection.Procedure.............................................................163
6.4.2. Constant-Effort.Supports...........................................................................................165
6.4.3. Spring.Support.Types.and.Installations.....................................................................166
6.4.4. Setting.of.Loads.—.Hot.Balance.and.Cold.Balance..................................................168
6.5. Support.of.Long.Risers.........................................................................................................170
6.5.1. Support.Schemes.......................................................................................................170
6.5.2. Support.Loads...........................................................................................................171
6.5.3. Analysis.Method........................................................................................................172
6.6. Significance.of.Support.Friction...........................................................................................172
6.6.1. Effects.of.Support.Friction........................................................................................172
6.6.2. Method.of.Including.Friction.in.the.Analysis............................................................174
6.6.3. Application.of.Friction.Force....................................................................................176
6.6.4. Methods.of.Reducing.Friction.Force.........................................................................176
6.7. Support.of.Large.Pipes..........................................................................................................178
6.7.1. Saddle.Supports.Using.Roark’s.Formula...................................................................179
6.7.2. Ring.Girder.Supports.................................................................................................180
6.7.3. Saddle.Supports.by.Zick’s.Method............................................................................185
6.7.4. Support.Types............................................................................................................190
6.8. Pipe.Stresses.at.Integral.Support.Attachments.....................................................................194
6.8.1. Power.Boiler.Formulas.for.Lug.Stresses....................................................................194
6.8.2. Kellogg’s.Choking.Model..........................................................................................198
6.8.3. WRC-107.Stress.Evaluation.......................................................................................202
6.9. Treatment.of.Support.Stiffness.and.Displacement................................................................205
Chapter.7
Flexible.Connections........................................................................................................................209
7.1. Basic.Flexible.Joint.Elements.and.Analytical.Tools.............................................................211
7.1.1. Generic.Flexible.Connections....................................................................................211
7.1.2. Bellow.Elements........................................................................................................213
7.2. Using.Catalog.Data...............................................................................................................218
7.2.1. Background.of.Catalog.Data.....................................................................................218
7.2.2. Using.the.Catalog......................................................................................................219
7.2.3. Calculating.Operational.Movements.........................................................................223
7.2.4. Cold.Spring.of.Expansion.Joint.................................................................................224
7.3. Applications.of.Bellow.Expansion.Joints..............................................................................225
7.3.1. Application.of.Axial.Deformation.............................................................................225
7.3.2. Lateral.Movement.and.Angular.Rotation..................................................................230
7.3.3. Hinges.and.Gimbals...................................................................................................232
7.4. Slip.Joints.............................................................................................................................235
Contents. vii
7.5. Flexible.Hoses.......................................................................................................................237
7.5.1. Types.of.Metallic.Hoses.............................................................................................237
7.5.2. Application.and.Analysis.of.Flexible.Hoses..............................................................238
7.5.3. Analysis.of.Hose.Assembly........................................................................................241
7.6. Examples.of.Improper.Installation.of.Expansion.Joints.......................................................241
7.6.1. Direction.of.Anchor.Force........................................................................................241
7.6.2. Tie-Rods.and.Limit.Rods..........................................................................................242
7.6.3. Improperly.Installed.Anchors....................................................................................244
Chapter.8
Interface.with.Stationary.Equipment..............................................................................................247
8.1. Flange.Leakage.Concern.......................................................................................................247
8.1.1. Standard.Flange.Design.Procedure...........................................................................248
8.1.2. Unofficial.Position.of.B31.3.......................................................................................250
8.1.3. Equivalent.Pressure.Method......................................................................................251
8.1.4. Class.2.Nuclear.Piping.Rules.....................................................................................254
8.2. Sensitive.Valves.....................................................................................................................255
8.3. Pressure.Vessel.Connections................................................................................................256
8.3.1. Loadings.Imposed.to.Piping.from.Vessel..................................................................257
8.3.2. Vessel.Shell.Flexibility...............................................................................................258
8.3.3. Allowable.Piping.Load.at.Vessel.Connections..........................................................264
8.3.4. Heat.Exchanger.Connections....................................................................................265
8.4. Power.Boiler.and.Process.Heater.Connections....................................................................265
8.5. Air-Cooled.Heat.Exchanger.Connections.............................................................................268
8.6. Low-Type.Tank.Connections...............................................................................................270
8.6.1. Displacement.and.Rotation.of.Tank.Connection......................................................270
8.6.2. Stiffness.Coefficients.of.Tank.Nozzle.Connection.....................................................272
8.6.3. Allowable.Piping.Loads.at.Tank.Connections...........................................................274
8.6.4. Practical.Considerations.of.Tank.Piping...................................................................280
Chapter.9
Interface.with.Rotating.Equipment.................................................................................................285
9.1. Brief.Background.of.Allowable.Piping.Load.on.Rotating.Equipment..................................286
9.1.1. When.Nobody.Knew.What.to.Do..............................................................................286
9.1.2. First.Official.Set.of.Allowable.Piping.Loads..............................................................287
9.1.3. Factors.Behind.the.Low.Allowable.Piping.Load.......................................................287
9.2. Evaluation.of.Piping.Load.on.Rotating.Equipment..............................................................288
9.2.1. Effect.of.Piping.Loads................................................................................................288
9.2.2. Movements.of.Nozzle.Connection.Point...................................................................289
9.2.3. Analysis.Approach.....................................................................................................290
9.2.4. Selecting.the.Spring.Hangers.to.Minimize.the.Weight.Load.....................................292
9.2.5. Multi-Unit.Installation...............................................................................................293
9.2.6. Fit-up.the.Connection................................................................................................294
9.3. Steam.Power.Turbine...........................................................................................................295
9.4. Mechanical.Drive.Steam.Turbines........................................................................................296
9.4.1. Allowable.Loads.at.Individual.Connection...............................................................296
9.4.2. Allowable.for.Combined.Resultant.Loads.................................................................297
9.4.3. Basic.Piping.Layout.Strategy.....................................................................................298
9.5. Centrifugal.Pumps................................................................................................................300.
9.5.1. Characteristics.Related.to.Piping.Interface...............................................................300
viii. Contents
9.5.2. Basic.Piping.Support.Schemes...................................................................................302
9.5.3. Non-API.Pumps........................................................................................................303
9.5.4. API.Standard.610.Pumps..........................................................................................304
9.6. Centrifugal.Compressors.......................................................................................................308
9.7. Reciprocating.Compressors.and.Pumps...............................................................................313
9.7.1. Pulsating.Flow...........................................................................................................313
9.7.2. Pulsation.Pressure......................................................................................................315
9.7.3. Pulsation.Dampener.for.Reciprocating.Pumps..........................................................316
9.7.4. Some.Notes.on.Piping.Connected.to.Reciprocating.Machine...................................319
9.8. Problems.Associated.With.Some.Techniques.Used.in.Reducing.Piping.Loads...................321
9.8.1. Excessive.Flexibility...................................................................................................321
9.8.2. Improper.Expansion.Joint.Installations.....................................................................322
9.8.3. Theoretical.Restraints................................................................................................322
9.9. Example.Procedure.for.Designing.Rotation.Equipment.Piping............................................324
Chapter.10
Transportation.Pipeline.and.Buried.Piping.....................................................................................329
10.1. Governing.Codes.and.General.Design.Requirements...........................................................330
10.1.1..B31.4.Liquid.Petroleum.Pipeline.............................................................................331
10.1.2..B31.8.Gas.Transmission.Pipeline............................................................................333
10.2. Behavior.of.Long.Pipeline.....................................................................................................335
10.2.1..Pressure.Elongation.................................................................................................335
10.2.2..Anchor.Force...........................................................................................................335
10.2.3..Potential.Movement.of.Free.Ends...........................................................................336
10.2.4..Movement.of.Restrained.Ends.................................................................................337
10.2.5..Stresses.at.Fully.Restrained.Section.........................................................................337
10.3. Pipeline.Bends......................................................................................................................339
10.4. Basic.Elements.of.Soil.Mechanics........................................................................................340
10.4.1..Types.of.Soils...........................................................................................................340
10.4.2..Friction.Angle..........................................................................................................340
10.4.3..Shearing.Stress.........................................................................................................341
10.4.4..Soil.Resistance.Against.Axial.Pipe.Movement........................................................341
10.4.5..Lateral.Soil.Force....................................................................................................343
10.4.6..Soil-Pipe.Interaction................................................................................................344
10.5. Example.Calculations.of.Basic.Pipeline.Behaviors...............................................................346
10.5.1..Basic.Calculations....................................................................................................346
10.5.2..Soil-Pipe.Interaction................................................................................................347
10.6. Simulation.of.Soil.Resistance................................................................................................348
10.7. Behavior.of.Large.Bends.......................................................................................................349
10.8. Construction.of.Analytical.Model.........................................................................................351
10.9. Anchor.and.Drag.Anchor.....................................................................................................353
Chapter.11
Special.Thermal.Problems...............................................................................................................357
11.1. Thermal.Bowing....................................................................................................................357
11.1.1..Displacement.and.Stress.Produced.by.Thermal.Bowing..........................................357
11.1.2..Internal.Thermal.Stresses.Generated.by.Bowing.Temperature................................359
11.1.3..Occurrences.of.Thermal.Bowing..............................................................................360
11.1.4..The.Problem.Created.by.a.Tiny.Line.......................................................................364
11.2. Refractory.Lined.Pipe...........................................................................................................365
Contents. ix
11.2.1..Equivalent.Modulus.of.Elasticity.............................................................................365
11.2.2..Hot-Cold.Pipe.Junction...........................................................................................366
11.3. Un-Insulated.Flange.Connections........................................................................................369
11.4. Unmatched.Small.Branch.Connections................................................................................369
11.5. Socket-Welded.Connections.................................................................................................370
Chapter.12
Dynamic.Analysis.—.Part.1:.SDOF.Systems.and.Basics..................................................................373
12.1. Impact.and.Dynamic.Load.Factor........................................................................................373
12.2. SDOF.Structures...................................................................................................................375
12.2.1..Working.Formula.for.SDOF.Systems......................................................................376
12.2.2..Un-Damped.SDOF.Systems....................................................................................376
12.2.3..Damped.SDOF.Systems..........................................................................................382
12.2.4..Summary.of.the.Characteristics.of.SDOF.Vibration................................................386
12.3. Damping...............................................................................................................................387
12.4. Sonic.Velocity.Versus.Flow.Velocity....................................................................................389
12.4.1..Sonic.Velocity..........................................................................................................390
12.4.2..Flow.Velocity...........................................................................................................392
12.5. Shaking.Forces.due.to.Fluid.Flow........................................................................................395
12.6. Safety.Valve.Relieving.Forces...............................................................................................397
12.6.1..Open.Discharge.System...........................................................................................397
12.6.2..Closed.Discharge.System.........................................................................................401
12.7. Steam.Turbine.Trip.Load.....................................................................................................403
Chapter.13
Dynamic.Analysis.—.Part.2:.MDOF.Systems.and.Applications......................................................409
13.1. Lumped-Mass.Multi-Degree.of.Freedom.Systems................................................................409
13.1.1..Mass.Lumping.........................................................................................................410
13.1.2..Free.Vibration.and.Modal.Superposition................................................................412
13.2. Piping.Subject.to.Ground.Motion.........................................................................................413
13.2.1..Response.Spectra.Method.......................................................................................415
13.2.2..Combination.of.Response.Spectra.Analysis.Results................................................417
13.2.3..Comparison.of.Modal.Combination.Methods.........................................................419
13.2.4..Puzzles.of.Absolute.Closely.Spaced.Modal.Combination.......................................421
13.2.5..Compensation.for.the.Higher.Modes.Truncated.....................................................422
13.2.6..Design.Response.Spectra.........................................................................................423
13.3. Account.for.Uncertainties.....................................................................................................426
13.4. Steady-State.Vibration.and.Harmonic.Analysis....................................................................428
13.4.1..Basic.Vibration.Patterns..........................................................................................428
13.4.2..Allowable.Vibration.Displacement.and.Velocity.....................................................429
13.4.3..Formulation.of.Harmonic.Analysis..........................................................................437
13.4.4..Evaluation.of.Vibration.Stress.................................................................................444
13.5. Time-History.Analysis..........................................................................................................446
13.5.1..Treatment.of.Damping.............................................................................................446
13.5.2..Integration.Schemes.................................................................................................448
13.5.3..Time.Step,.Stability,.and.Accuracy..........................................................................450
13.5.4..Example.Time-History.Analysis..............................................................................451
x. Contents
Appendix.A......................................................................................................................................459
Appendix.B......................................................................................................................................461
Appendix.C......................................................................................................................................462
Appendix.D......................................................................................................................................464
Appendix.E......................................................................................................................................466
Appendix.F......................................................................................................................................474
INDEX.............................................................................................................................................475