Pressure Pipe Wall Thickness and Flange Rating Calculation Using a Script and a Generic 4D Chart

Pressure Pipe Wall Thickness and Flange Rating Calculation Using a Script and a Generic 4D Chart Popular

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Pressure Piping Thickness and Flange Rating Calculation Rev 3.zip

Pressure Pipe Wall Thickness and Flange Rating Calculation Using a Script and a Generic 4D Chart


In the oil and gas industry high pressure applications are the norm rather than the exception. Process engineers may employ Flownex® to model liquid or gas piping systems as part of their heat and mass balance, and pipe sizing calculations. However, in high pressure applications it is also necessary to design the pressure piping and associated connected flanges to safely contain the high pressure fluid. The process engineer often has to rely on others to determine the required pipe schedules (wall thickness) and flange ratings. This is less than ideal since pipe schedule changes which occur after the process design stage could mean changes in pipe sizes to reduce velocities and / or pressure losses. This will inevitably lead to significant rework of the Flownex® model, initial datasheets and Piping and Instrumentation Diagrams (P&IDs) and add to the cost of the project.

Flownex® does not offer the facility to perform wall thickness and flange checks in a built-in component or script since almost every nation has their own pressure vessel and pressure piping standards. However, Flownex®has a very powerful facility in terms of its scripting capability, and combined with the Generic 4D chart library, all the tools required are available to implement pressure piping calculations according to any design standard. In fact, any data table oriented calculation procedure may be implemented using this approach. This case study demonstrates the implementation of three such international standards – ASME B31.3, AS 1210 and AS 4041 – in a simple script. ASME B31.3 is a widely used US Standard for pressure piping and AS 1210 is an Australian and New Zealand Standard for pressure vessels and AS 4041 is the pressure piping equivalent. It is also further demonstrated how to use the Generic 4D charts as a material property library to be used by the script. The script demonstrates the implementation of:

  • Corrosion allowances
  • Under-tolerance
  • Minimum required wall thickness to safely contain the fluid at design pressure and temperature
  • Calculation of a design margin
  • Selection of an ASME B16.5 flange rating

Using this simple script and Generic 4D chart in any Flownex® model, pressure piping and flanges can be easily checked for compliance with any international standard well before piping engineers are required to verify the structural integrity of the piping system.


The model has been updated to include the following materials:

  • ASTM A106 Grade B with ASTM A105
  • ASTM A312 TP304 with ASTM A182 Gr.F304
  • ASTM A312 TP316 with ASTM A182 Gr.F316
  • ASTM A790-S31803 with ASTM A182 Gr.F51

Furthermore, the Generic 4D charts have been modified to allow data entry in the same units as those found in the ASME standards, i.e. bar-g and MPa-g. Three run-time warnings have also been added to check operating conditions against specified design conditions.


The full case study discussion document is available on the Flownex® web page in the Case Studies section: