WORK WITH US
  • About CADE
  • Sectors

    Thermosolar and Renewables

    More info

    Oil & Gas

    More Info

    Power Generation

    More Info

    Other Industries

    More Info
  • Consultancy

    Heat Transfer Equipment Technology

    Process Technology
    Thermal & Hydraulic Design
    Mechanical Design
    Detail Engineering
    Performance Assessment

    More info

    Simulation Engineering

    FEA - Finite Element Analysis
    CFD - Computational Fluid Dynamics
    CHT - Conjugated Heat Transfer

    More info

    Engineering Analysis

    Fitness For Service Assessment
    Mechanical Integrity Remaining Life
    Evaluation Failure Root Cause Analysis
    Performance Assessment

    More info

    Process & Mechanical Consulting

    3rd Party Engineers
    Expert Witness
    Due Dilligence Assessment
    Warranty Resolution

    More info

    Structural Engineering

    Design verification / validation by structural calculation
    Study and definition of loads
    Structural design (conceptual and detailed 3D-2D)

    More info
  • Engineering

    Basic & Detail Engineering

    Data Sheets
    Valve Specifications
    Control valves
    Detailing Engineering
    Plant Layouts and General Arrangement drawings
    Much more

    More info

    Process Engineering

    Chemical Processes
    Thermodynamic Processes
    Heat Transfer
    Hydraulics

    More info

    Equipment Engineering

    Pressure Vessels
    Heat Exchangers
    Reactors, Columns and Towers
    Tanks

    More info

    Piping Engineering

    2D / 3D Design Piping Design
    Flexibility Analysis
    Advanced Piping Flexibility
    Analysis (Finite Element Analysis)

    More info

    3D Laser Scanner

    Assessment of Existing Industrial Assets
    Equipment Manufacturing Dimensional Control
    Brownfield Projects and As-Built Engineering

    More info
  • R&D
    Edit Content

    Eclosion

    Generation, storage and transport of renewable hydrogen and biomethane.

    More info
    On going
    TES4Trig logo

    Tes4trig

    Innovative solution for the generation of heat, cold and electricity from solar energy

    More info
    On going
    Edit Content
    logo cade engineering cade soluciones de ingeniería - Servicios de Ingeniería y Consultoría

    Research, Development and Innovation

    CADE has develop its own R&D activities since 2009 around new disruptive technologies and industrial applications related to renewables and clean-tech industries

    Further information
    logo cade engineering cade soluciones de ingeniería - Servicios de Ingeniería y Consultoría

    Investigación, Desarrollo e Innovación (I+D+i)

    Desde 2009, CADE desarrolla actividades de Investigación, Desarrollo e Innovación (I+D+i) en torno a nuevas tecnologías disruptivas y aplicaciones industriales relacionadas con energías renovables e industrias de tecnología limpia.

    Más información
  • Technologies
    Edit Content

    process CSP

    Custom solutions for the integration of thermosolar heat in the industry

    More info

    solidTES

    Thermal energy storage system in concrete

    More info

    zeroSD

    Zero-Sludge-Disposal - Zero-Sludge-Disposal Solution using SCWG Technology

    More info

    zeroLD

    Zero Liquid Discharge - Zero Liquid Discharge Solution for Wastewater Treatment

    Más información
    Edit Content

    Cade Cobots

    CADE Cobots is a business line framed in our portfolio of solutions in Industry 4.0 of CADE for optimization of industrial processes, through collaborative robots or cobots, comprehensive process consulting, artificial vision, as well as development and supply and integration of complete turnkey solutions in hand. CADE Cobots allows us to respond to our idea of intelligent industrial models that are adaptable to needs and processes, applied to companies of all sizes.

    Más información
  • Publications
Search
Close this search box.

STRESS INTENSITY FACTOR (SIF) FOR SPECIAL GEOMETRIES IN PIPING STRESS ANALYISIS

SIF according to ASME B31J for special geometries not covered in ASME B31.1 and ASME B31.3 codes

PROBLEM DEFINITION

Piping Design is a critical component of engineering projects and process plants.  In order to get safety pipe systems, the flexibility analysis (stress analysis) is essential, because the pipe stress analysis predicts stresses in the pipeline due to thermal gradients, weights and pressures. 

Stress Intensification Factors (SIF) are  parameters that allow the designer to estimate the maximum stresses in the pipe line and the fatigue failure in a piping component or joints. Following paragraphs explain in detail the determination of the stress intensity factor  for special geometries not covered by ASME B31.1 or B31.3 codes.

WHAT IS THE STRESS INTENSIFICATION FACTOR?

The Stress Intensification Factor (SIF) is a multiplier factor on nominal stress for typically bends and intersection components so that the effect of geometry and welding can be considered in a beam analysis (as for example calculations performed with CAESAR II software). The stress intensity factor is used in a pipe stress analysis as follow:

                       (Beam stress)· (SIF) ≤ Allowable Stress

ASME piping codes (ASME B31.1 and ASME B31.3) stablish the formulation to obtain the stress intensification factor “I” and flexibility factor “k” for fitting geometries according to ASME B16.9.

CADE table D300, flexibility factor, k, and stress intensitification factor, i
Table D300 - ASME B31.3 - Examples of Stress Intensification Factor formulation for some geometries.

METHODOLOGY

STRESS INTENSIFICATION FACTOR (SIF) FOR SPECIAL FITTING GEOMETRIES

For special geometries (such as valves, strainers, anchor rings, bands, etc.) or modified geometries from ASME B16.9  codes (as for instance trimmed elbows), it is necessary to obtain a valid stress intensification factor in order to avoid problems due to flexibility analysis. These values of SIF are out of the scope of design codes as ASME B31.1 or ASME B31.3. However, ASME B31J code provides the standard method for determining the stress intensification and flexibility factor required.

According to ASME B31J, there are two ways in order to obtain SIFs:

  • Real test specimen with the real geometry.
  • Virtual test specimen, FEM analysis.

The advantage of the virtual test specimen (FEM analysis) is obvious because a real test specimen (especially for larger diameters) can be very expensive compared with the finite element analysis.

ANALYSIS METHODOLOGY - STRESS INTENSIFICATION FACTOR FEM ANALYSIS

FEM analysis will allow to simulate the standard test method for determining stress intensification factors (i-factors) for metallic components as per ASME B31J and stress-life (S-N) fatigue model per Markl fatigue test curve.

Following steps summarizes analysis methodology to determinate stress intensification factor “i”:

analysis methodology stress intensification factor fem analysis
Steps to obtain the stress intensification factor

FEM SIF CALCULATIONS ACCORDING TO ASME B31J AND PIPE FLEXIBILITY CALCULATIONS

CADE is pleased to have participated in many relevant worldwide projects where the bi-directional calculations (between FEA analysis and pipe flexibility analysis with CAESAR II software) are required. A correct evaluation of the stress intensity factors in special geometries reduces the risk of failure in the pipeline, therefore, this part of the calculation must be essential in the flexibility stress analysis. Nowadays, most of c piping specifications require this calculation.

Following images show an example of project conducted by CADE, which results obtained in the determination of the stress intensity factor (SIF) in a modified geometry (trimmed elbow) was used in the flexibility calculations performed with CAESAR II software.

Stress intensity factor for special geometries in piping stress analysis
Trimmed elbow test specimen results. FEM analysis.
FEM SIF Calculations
Table. SIF Comparison Trimmed vs Untrimmed elbow.
Pipe flexibility analysis with the SIF obtained in the trimmed elbow
Caesar II Pipe flexibility analysis with the SIF obtained in the trimmed elbow.

SUMMARY AND CONCLUSIONS​

  • Stress Intensification Factor (SIF) is a multiplier factor on nominal stress obtained in a beam analysis (as for instance, calculations performed with CAESAR II software).
  • ASME B31.1 and ASME B31.3 codes established the stress intensification factor (SIF) for geometries show in ASME B16.9 code (normal geometries).
  • For special or modified geometries (such as valves, strainers, anchor rings, bands, trimmed elbows, etc.) the stress intensification factor shall be calculated according to a specimen show in ASME B31J code which establish two ways in order to obtain the stress intensification factor: real test specimen in a laboratory or virtual test specimen with a FEM analysis.
  • FEM (Finite Element analysis) is the cheapest option to simulate the test specimen mandatory in ASME B31J in order to obtain a real SIF.
  • CADE engineering is the best option to perform these types of multidisciplinary analyses, because it has the engineering knowledge (with more than a thousand projects in more than 15 years of activity), highly skilled and committed team of engineers, together with a solid business management, which make CADE an independent leading engineering and consultancy company around technology, equipment and plants within oil&power industries.

FURTHER INFORMATION ABOUT PIPING STRESS ANALYSIS

CADE provides engineering, simulation and consulting services aimed to assess critical plant equipment, high temperature piping, pressure vessels and structures when they are not performing as expected, a failure has occurred or their mechanical integrity and remaining life must be evaluated. 

OTHER PROJECTS

See more

CADE Engineering Contact

Seeking engineering and consulting services? Tell us about your project on the following form and one of our specialists will reach out to you as soon as possible.

Also, you can call +34 967 19 01 72 or send an email to cade@cadesoluciones.com.

Follow us in our social networks

Linkedin Youtube Instagram

SERVICES

TECHNOLOGIES

SECTORS

ABOUT US

legal notice

CADE Engineered Technologies

CADE Soluciones de Ingeniería, S.L.

HEADQUARTERS

Parque Científico y Tecnológico
Paseo de la Innovación 3, 02006 Albacete – Spain

Tel. +34 967 19 01 72

MADRID OFFICE

Santiago Bernabéu, 3 Entreplanta
28036
Madrid – Spain

© Copyright 2003-2024 Cade Soluciones de Ingeniería S.L. - Terms and Conditions of Use

Albacete

Parque Científico y Tecnológico

Paseo de la Innovación 3, 02006 Albacete – España

Tel. +34 967 19 01 72

Madrid

Santiago Bernabéu, 3 Entreplanta


28036

Madrid – España

 

Cargar más

Albacete

Parque Científico y Tecnológico

Paseo de la Innovación 3, 02006 Albacete – España

Tel. +34 967 19 01 72

Madrid

Santiago Bernabéu, 3 Entreplanta
28036 Madrid – España

Contact us

I guess you are interested in what we do

If you please, contact us and tell us about your project to inform you what we can do for you

Can we call you?

We inform you about our engineering solutions