Case Study: Transportation Load Analysis of MEGCs Using Equivalent Static Loads

Project Overview

This project outlines the use of advanced Finite Element Analysis (FEA) to evaluate the structural response of Multiple Element Gas Containers (MEGCs) under representative transportation loads. Equivalent static accelerations derived from applicable international transport standards were applied to ensure structural integrity and compliance with regulatory load requirements.

Objectives of the Study

The primary objective of this case study is to:

• Define and apply equivalent static transportation loads for MEGCs based on international regulations

• Evaluate stresses and structural response under each transportation load case

• Identify critical load cases governing MEGC structural performance

• Support design decisions for verification and certification of MEGCs under transportation conditions

Geometry

MEGC System

The MEGC assembly modeled in this case study represents a bundle of pressurized gas cylinders mounted within a support frame for road, rail, and maritime transportation. Key geometric features include:

• Cylindrical gas cylinders

• Welded structural frame

• Lifting lugs, tie-down points, and handling interfaces

• CAD geometry directly imported into FEA software

Material Properties

Material properties used for the FEA model include:

• Elastic modulus (E)

• Poisson’s ratio (ν)

• Yield strength (Sy)

• Mass density (ρ)

These properties are defined for the frame, cylinders, and connection hardware. Accurate mass properties are necessary to derive equivalent static forces from acceleration factors.

Contact and Structural Modeling

• Fully bonded contacts at welded interfaces

• Frame and cylinder interfaces modeled to avoid separation under applied loads

• Local mesh refinement at lifting points, frame junctions, and supports

• Rigid and flexible constraints representing mounting conditions

Governing Equations:

Equilibrium (Static)

Equivalent static forces are applied as body accelerations

Simulation Methodology

Step 1: Geometry Import

• MEGC CAD model imported into FEA environment

• Symmetry was identified per load case (Only lateral load case shown in the images)

• For the Longitudinal load case, different symmetry plane was used (entirely different model)

• Cylinders were modelled as point masses

• Critical load application points identified

Step 2: Meshing

• Solid 3D elements used across MEGC and frame

• Local refinement at high stress regions

• Mesh convergence verified for global and local stress accuracy

Step 3: Load Definition

• Equivalent static accelerations applied to body mass

• Separate load cases for each transportation direction. The images are shown for lateral direction load case only

Step 4: Boundary Conditions

• Mounting restraints applied to simulate transport mountings

• Loads applied independently and in critical combinations

• Symmetry was also applied to the mid plane.

Step 5: Solver Execution

• Linear static analysis performed for each load case

• Reaction forces and stress distributions extracted

Post-Processing and Key Results

Key outputs analyzed include:

• von Mises stress distributions

• Maximum stress regions in support frame and lifting points

• Comparison of stress results among load cases

• Identification of governing load cases

Results showed that longitudinal braking and maritime combined loads produced the highest stress intensities in the MEGC support frame. All evaluated stresses remain below allowable limits for the selected material properties.

Engineering Insights Gained

• Longitudinal and vertical combinations govern structural design

• Lifting and handling loads require careful reinforcement at attachment points

• Equivalent static approach provides conservative yet practical evaluation

Industrial Applications

Multiple Element Gas Containers (MEGCs)

Transportation load analysis using FEA is critical for MEGC systems used for bulk transport of compressed and liquefied gases. The defined equivalent static load cases ensure structural integrity of the cylinder bundle, frame, lifting lugs, and tie-down points during road, rail, and maritime transportation in compliance with international regulations.

Tube Trailers and Gas Cylinder Transport Systems

Tube trailers transporting high-pressure gas cylinders are subjected to severe longitudinal, lateral, and vertical loads during braking, cornering, and road irregularities. The methodology presented in this study is directly applicable for assessing structural adequacy of tube supports, saddles, trailer frames, and end restraints under transportation loading conditions.

Skid-Mounted Process Equipment

Skid-mounted assemblies such as gas regulation skids, compressor skids, and pressure reduction skids experience similar transportation and handling loads as MEGCs. Equivalent static load analysis ensures that skids, base frames, pipe supports, and equipment anchoring systems remain within allowable stress limits during shipment and installation.

Modular Pressure Equipment and Transport Frames

Modular pressure vessels, ISO frames, and packaged equipment units designed for intermodal transport require verification under combined acceleration and lifting loads. The presented FEA approach supports structural evaluation of transport frames, corner fittings, and lifting points for safe handling and transport.

Hazardous Goods Transportation Systems

For systems transporting hazardous or high-energy contents, including industrial gases and specialty chemicals, transportation load analysis provides a critical verification step. The defined load cases help mitigate risks associated with accidental impacts, handling mishaps, and extreme transport conditions.

Benefits to Industry

• Code-aligned structural assessment

• Identification of critical transport load conditions

• Design guidance for load path reinforcement

• Reduced risk of in-service failure during transit

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