Overcoming Beam Modeling Limitations in Piping Design

As piping systems evolve, engineering methods must adapt to meet their increasingly complex demands. Traditional beam modeling, while foundational in piping analysis, often falls short in addressing the intricate realities of modern designs.

At Paulin Research Group, we offer advanced solutions that bridge these gaps, providing enhanced accuracy through nonlinear and Finite Element Analysis (FEA) approaches. Let’s dive in.

Challenges with Beam Modeling?

Beam modeling is a widely used method in the piping industry for stress analysis, relying on simplified representations of pipes and fittings to calculate stresses. However, this approach is inherently limited, particularly when applied to large-diameter piping systems, complex geometries, or conditions involving high pressure and temperature variations. Stress Intensification Factors (SIFs), derived from decades-old research, are still often used to approximate local stress conditions, leading to potentially inaccurate or overly conservative results.?

In some cases, large-diameter piping exists and can operate under extreme conditions, and traditional beam modeling may not provide the precision needed to ensure safety and reliability.

The ASME B31.3 code, while comprehensive, only offers broad guidance on critical issues such as vibration and high fluid momentum loads, stating they "shall be taken into account." This leaves engineers and designers navigating a gray area where more accurate and detailed analysis is essential.

The PRG Solution: Advanced Analysis in Minutes

PRG's software solutions, including FEPipe, NozzlePRO, and PCLGold, address these limitations by employing nonlinear and FEA-based approaches, providing more comprehensive modeling capabilities than conventional beam methods.

1. Nonlinear Analysis for Realistic Simulations?

PRG's tools utilize nonlinear analysis to account for material behavior under extreme loads. In situations where piping systems must endure significant stress, such as thermal expansion or high fluid momentum loads, beam models can underestimate deformation risks. By capturing non-linear material behavior, PRG’s software enables engineers to anticipate and design for real-world scenarios.

2. Finite Element Analysis (FEA) for Precision?

Unlike beam modeling, FEA allows for detailed representation of actual pipe geometries, accounting for both membrane and bending actions. This is particularly important for large diameter-to-thickness (D/t) ratios and complex geometries such as pipe intersections, where SIFs may be inadequate. FEA provides a more nuanced view of stress distribution, including the identification of local hotspots that beam models might miss.

3. Shell Modeling for Complex Load Cases?

PRG software incorporates shell modeling, which goes beyond traditional beam elements by capturing local stresses and providing a more accurate assessment of the piping system’s response to high fluid momentum loads and other complex conditions. This is crucial for understanding the true behavior of piping systems and ensuring the design is both efficient and safe.

ASME Research and Shell vs. Beam Modeling?

In past ASME research, several have advocated for the inherent limitations of beam modeling, particularly for systems facing high fluid momentum loads and dynamic forces. Some have emphasized that while beam modeling is convenient for simple systems, more detailed analysis is often required for modern piping applications.1?

PRG’s use of 18-degree-of-freedom beam elements, as implemented in FEPipe, allows for improved evaluation of ovalization and more precise stiffness calculations. However, the transition to shell elements is sometimes necessary to fully understand stress conditions, particularly for large piping or non-linear scenarios where traditional methods fall short.

Real-World Applications: Advancing LNG Plant Safety?

The LNG plant in Australia has revealed significant shortcomings in relying solely on traditional beam modeling methods for piping systems that handle cryogenic temperatures, high pressures, and dynamic loads. Through the use of PRG's FEPipe and NozzlePRO, engineers were able to employ shell modeling to accurately simulate local stresses, thus ensuring a more reliable and safe design [2][3].

For example, pneumatic testing—a standard procedure for verifying system integrity—has historically been fraught with risks, particularly when industry codes provide insufficient guidance. Using PRG’s software, engineers could better predict and mitigate risks, enhancing safety protocols and reducing the likelihood of catastrophic failure.

The Future of Piping Design: Modern Solutions for Modern Challenges?

As piping design continues to grow in complexity, engineers must leverage modern analysis tools to overcome the inherent limitations of outdated methods. PRG’s software not only fills the gaps left by traditional beam modeling but also offers capabilities that ensure compliance with modern standards while pushing the boundaries of what is achievable in piping system design.?

With FEA and advanced shell modeling, PRG provides engineers and designers with the tools needed to tackle today’s most challenging piping scenarios, ensuring designs that are safe, reliable, and capable of meeting the demands of the energy industry. By adopting these advanced methods, engineers can move beyond conservative assumptions, delivering more efficient and resilient piping solutions for the future.?

To learn more, visit www.paulin.com.

References

1 Weyer, R. (2022).?OVERVIEW OF PIPING STRESS ANALYSIS USING SHELL ELEMENTS. PVP Conference. 17 July 2022, Las Vegas, Nevada.?

2?Weyer, R. (2020).?IMPROVING LNG PLANT PIPING (OR HOW LNG PLANTS ARE IMPROVING PIPING). PVP Conference, 20 July 2020, Virtual, Online.?

3 Chevron Policy, G. and P. A. Gorgon Project.?https://australia.chevron.com/our-businesses/gorgon-project. 2022, February 22.?

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