METAL BELLOWS FATIGUE & DAMAGE ASSESSMENT

Sample Project — DN500 Metal Bellows Expansion Joint

Compare EJMA 10th Edition, EN 14917, ASME VIII Division 1 Mandatory Appendix 26, and AD 2000 B13 results on a single dashboard.

U-Shaped · UnreinforcedCustom MaterialSingle Bellows

—Overall assessment

Calculating inputs…

N

Governing fatigue life——

D

Maximum Miner damage—Limit ≤ 1.000

Δq

Equivalent movement—mm / convolution

F

Estimated pressure thrust—At maximum pressure

Fatigue Life Comparison by Standard

Allowable cycles and design target

Calculated lifeRequired cycles

Quick Results

Current load cycle

Critical Warnings

Scope and input checks

Stress Components

Automatic result for unreinforced U-shaped bellows

INPUT CONTROL CENTER

Project and Design Inputs

Highlighted fields feed directly into the calculation engine. Material selection updates E at the design temperature.

Project Identification

Report title and traceability information

Project / customer name Calculation number Customer Prepared by Checked by Revision Date Project notes

Expansion Joint Configuration

Defines the scope of the automatic stress calculation

Bellows type Configuration Number of bellows elements Manufacturing condition Circumferential weld Required cycles Nspe

Standards included in the governing assessment EN 14917 ASME App.26 EJMA 10 AD 2000 B13

Bellows Geometry

SI units: mm

Dm = Di + np·ep + w

Inside diameter Di

mm

Single-ply thickness ep

mm

Number of plies np Forming factor Convolution height w

mm

Convolution pitch q

mm

Mean radius rm

mm

Number of convolutions N Bellows flexible length lB

mm

Universal effective length l*

mm

End tangent length Lt

mm

Pressure and Material

Verify preliminary material values against the material certificate or applicable code tables

Material Position 1 pressure P1

MPa

Position 2 pressure P2

MPa

Metal temperature

°C

Material family EJMA class Poisson ν E0

MPa

EB

MPa

Proof / yield strength K

MPa

Standard Correction Factors

Change defaults only with a documented engineering justification

ASME Kg EJMA fc AD safety factor SL AD R(p) AD R(w) AD plasticity factor B AD weld factor f1 EN cσ manual EN cPy EN cPθ

Manual Total Stress Inputs

Used for reinforced or toroidal geometries and validated external analyses. 0 = automatic.

EN σeq

MPa

ASME St

MPa

EJMA St

MPa

AD Δσvges

MPa

AD torsion ΔσT

MPa

PARAMETRIC DESIGN SCREENING

Design Laboratory

Sweep the number of convolutions and ply thickness to compare lower-spring-rate alternatives that meet the fatigue-life target.

Sweep Range

Candidate geometries derived from the current project

Not run yet

Minimum N Maximum N Minimum thickness

mm

Maximum thickness

mm

Thickness increment

mm

Target life factor

× Nspe

Maximum candidates Sensitivity variable

This module is a parametric screening tool, not a final automated design. Manufacturing feasibility, squirm stability, tolerances, welding, hardware, and code approval must be verified separately.

Recommended Alternative

Balances low spring rate and compact flexible length among acceptable candidates

The best candidate will appear here after the sweep is run.

#

Candidates evaluated—Parametric combinations

✓

Meeting target—Including critical checks

N

Best governing life—Cycles

K

Recommended spring rate—N/mm

Candidate Geometry Table

First 60 results; acceptable candidates are listed first

Rank	N	t	Lb	Δq	Governing life	Miner D	Kb	Check
The sweep has not been run.

Sensitivity Curve

Effect of the selected parameter on governing life

Current Design / Recommendation

Key engineering differences

TWO-ENDPOINT MOVEMENT METHOD

Movement and Critical-Fiber Analysis

Axial, lateral, and angular movements are converted to equivalent movement per convolution using two endpoint positions.

Cycle Endpoint Positions

Enter signs according to the actual installation coordinate system

Position 1

Name

x

mm

y

mm

θ

°

Description

Position 2

Name

x

mm

y

mm

θ

°

Description

Critical-Fiber Movement Envelope

Full range between the positive and negative critical fibers

Δq

ASME / EJMA—mm/convolution

EN

EN-corrected Δq—mm/convolution

x

Axial component—mm/convolution

y

Lateral component—mm/convolution

Position Calculation Table

The two critical fibers are evaluated separately at each position

Position	Δqx	Selected Δqy	Δqθ	Fiber +	Fiber −	EN Fiber +	EN Fiber −

MINER LINEAR DAMAGE

Multi-Level Load Spectrum

Define start-up, shutdown, and operating cycles in separate rows. The total usage factor D must be ≤ 1.

Active	Load case	ni	Pmax MPa	Δq mm/convolution	EN St manual	ASME St manual	EJMA St manual	AD 2ε % manuel	EN Ui	ASME Ui	EJMA Ui	AD Ui

Cumulative Damage Overview

The 1.0 line is the acceptance limit

CODE-BY-CODE TRACEABILITY

Standard Results and Formula Traceability

Each result is presented with its scope of applicability, stress components, and fatigue curve.

SCOPE & INPUT VALIDATION

Geometry and Applicability Checks

Code scope conditions are evaluated together with the supplied AD 2000 preliminary-geometry formulas.

Code Scope Checks

Critical failures affect the governing result

Preliminary Geometry Envelope

Guidance values derived from the source Excel formulas

This envelope is not a final code calculation; the manufacturing method, tolerances, and forming-induced thinning must be verified separately.

PRINT-READY ENGINEERING OUTPUT

Engineering Calculation Report

Use your browser’s PDF printer to generate a professional report.

TECHNICAL BASIS

References and Application Limits

This application is an engineering aid that combines the supplied standards and calculation workbook.

Important engineering notice

Results depend on the accuracy of the entered geometry and material properties. This application does not replace verification of manufacturing tolerances, weld details, corrosion, vibration, flow-induced effects, hardware, anchors, guides, pressure-thrust restraint, NDT, or PED conformity assessment. The final design must be reviewed by a qualified metal bellows expansion joint engineer.