Wall Thickness Allowances

The RF-PIPING and RF-PIPING Design add-on modules allow you to design piping systems according to EN 13480-3 [1], ASME B31.1 and B31.3. In the case of the European standard, the determination of pipe stresses is based on the formulas of Section 12.3 Flexibility Analysis. Depending on the stress type, one or more resulting moments is applied without regard to each other. This differentiation occurs when determining the stresses due to occasional loads, for example.

For stress calculations, some standards use the "wall thickness analysis". We get the wall thickness by subtracting corrosion, abrasion allowance, manufacturing allowances (threading, grooving, and so on), and mill tolerances from the nominal wall thickness. All necessary values can be entered in the "Piping Cross‑Section" dialog box, "Stress Analysis Parameters" tab.

Not all structural elements of a real building are included in a structural model. As an example, we can look at a pipe that runs along a steel girder frame.

• Graphical input of piping systems and piping components
• Illustrative visualization of piping systems and piping components in RFEM graphic window
• Comprehensive libraries for piping cross‑sections and materials
• Comprehensive libraries for flanges, reducers, tees, and expansion joints
• Consideration of piping structure (insulation, lining, tin‑plate)
• Automatic calculation of stress intensification factors and flexibility factors
• Specific piping action categories for load cases
• Optional automatic combinatorics of load cases
• Consideration of material properties (modulus of elasticity, coefficient of thermal expansion) either during operating temperature (default setting) or during reference (assembly) temperature of material
• Consideration of strain and uplift due to pressure (Bourdon effect)
• Interaction between the supporting structure and the piping system

After modeling piping systems in RFEM using RF‑PIPING and defining loads as well as load and result combinations, you can carry out pipe stress analysis in the RF‑PIPING Design add‑on module.

You can select all or only some pipelines and loads, load or result combinations for piping design. The material library provides various materials according to EN 13480‑3, ASME B31.1‑2012, and ASME B31.3‑2012 standards.

After the calculation, the results are displayed in clearly arranged windows; for example, by cross‑section, by pipeline, or by members. You can also display the design ratio graphically on the entire model in RFEM. This way, you can quickly recognize critical or oversized areas of the cross-section.

In addition to the input and result data, including design details displayed in tables, you can add all graphics into the printout report. This way, comprehensible and clearly arranged documentation is guaranteed. You can select the report contents and extent specifically for the individual designs.

• Design according to EN 13480-3, ASME B31.1-2012, and ASME B31.3-2012
• Check of the minimum required wall thickness of the pipes, taking into account manufacturing allowances, corrosion, and welding factor
• Analysis of stresses due to sustained loads, sustained and occasional loads as well as due to thermal expansion
• Result documentation with tables and graphics in the RFEM printout report