Meena Rezkallah, P.Eng.

3.0 Modeling And Analysis Of The Piping System

Updated: Dec 20, 2020

The first two sections of these pipe stress analysis notes have served to give the user an overview of the requirements of pipe stress analysis. This section presents the task on a detailed level, presenting ideas for modeling of various piping configurations and explaining specific analyses which may be performed to evaluate individual piping components.

Included in this section is information on the following subjects:

  1. Computer representation of basic elements

  2. Piping configuration modeling techniques

  3. Expansion joint modeling and evaluation

  4. Nozzle evaluation, including evaluation of equipment loads, determination of nozzle/vessel stresses, and estimation of nozzle/vessel connection flexibilities

  5. Piping restraints/structural modeling

  6. Miscellaneous topics (cold spring, underground pipe, plastic pipe, jacketed pipe, flange leakage analysis, etc.)


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Pipe Stress Analysis Notes


 

 
3.1 Computer Representation Of Basic Elements
 
3.2 Piping Configuration Modeling Techniques
 
3.3 Expansion Joint Modeling And Evaluation

3.3.1 Expansion Joint Stiffnesses
 
3.3.2 Evaluation of Expansion Joint Allowable Movements
 
3.3.3 Use of the ERATE Program
 
3.3.4 Modeling of Unbalanced Pressure Force
 
3.3.5 Modeling of Tie Rods
 
3.3.6 Expansion Joint Assemblies

3.4 Piping Nozzle Evaluation

3.4.1 Equipment Nozzle Load Analysis

3.4.1.1 NEMA SM23 Standard for Steam Turbines
 
3.4.1.2 API 610 Standard for Centrifugal Pumps
 
3.4.1.3 API 617 Standard for Centrifugal Compressors
 
3.4.1.4 API 661 Standard for Air Cooled Heat Exchangers
 
3.4.1.5 HEI Standard for Closed Feedwater Heaters

3.4.2 Calculation of Vessel Stresses Due to Nozzle Loads

3.4.2.1 Calculation of Vessel Stresses Due to Nozzle Loads
 
3.4.2.2 Running a Sample WRC 107 Calculation
 
3.4.2.3 Evaluating Vessel Stresses
 
3.4.2.4 Completing the Sample Calculation

3.4.3 Estimation of Vessel Nozzle Flexibilities

3.4.3.1 Use of WRC Bulletin 297
 
3.4.3.2 Modeling Nozzles for Flexibility Calculations

3.5 Restraint Modeling

3.5.1 Restraint Types

3.5.1.1 Anchor
 
3.5.1.2 Restraint
 
3.5.1.3 Spring Hanger
 
3.5.1.4 Hanger
 
3.5.1.5 Support

3.5.1.6 Snubber
 
3.5.1.7 Sway Brace

3.5.2 Non-linear Effects

3.5.2.1 Friction
 
3.5.2.2 One-Way Restraints
 
3.5.2.3 Gaps
 
3.5.2.4 Large Rotation Restraints
 
3.5.2.5 Bi-linear Stiffnesses

3.5.3 Evaluation of Restraint Stiffness

3.5.3.1 Use of the Structural Steel Modeler

3.5.4 Use of CNODES When Modeling Restraints

3.6 Miscellaneous Topics

3.6.1 Consideration of Cold Spring
 
3.6.2 Fiberglass Reinforced Plastic Pipe
 
3.6.3 Underground Pipe

3.6.3.1 Modeling Soil Restraint
 
3.6.3.2 Automated Underground Piping Modeler

3.6.4 Jacketed Pipe
 
3.6.5 Flange Leakage Analysis

3.6.5.1 Equivalent Pressure Calculation
 
3.6.5.2 Flange Leakage Analysis Module

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