Case Study: Structural Compliance of Mining Tank Frame FEA, Redesign, and Welding Strategy for AS 4991 Compliance

The Challenge

A client-supplied side-lift mining tank frame was found to be structurally unsuitable under actual vehicle-mounted load conditions. The design was intended for use in mining environments and required certification to AS 4991 for lifting and transport, including a 1.5g dynamic amplification factor. Engineering Assessment

Kleidouchos Engineering performed a full structural analysis using FEA, applying:

• Vehicle-mounted load case with dynamic amplification

• Stress threshold of 350 MPa, based on yield strength requirements

• Conservative modeling assumptions: no weld throat, minimal plate thickness, and aggressive mesh refinement.

The original design showed localized over-stress, breaching the allowable threshold and posing a compliance risk. Our Solution

We proposed a revised tank frame design to:

• Strengthen critical joints

• Improve load path uniformity

• Maintain ease of fabrication

• Ensure all global stresses remained below 350 MPa

The improved design successfully passed structural compliance without excessive material addition. Localized Hotspot Interpretation

A peak of ~390 MPa was observed at a sharp joint due to mesh singularity. Based on previous field experience and identical builds by the client (Stemtite), this was deemed non-critical and justifiable with fabrication tolerance. Weld Procedure Specification

To support fabrication integrity, we developed a welding strategy tailored to the frame’s material and application:

• GMAW (ER70S-6 / ER80S-D2): For shop welds with clean finish

• SMAW (E7018): For on-site or critical low-hydrogen joints

• FCAW (E71T-1 / E80T-1): Optional for higher deposition or positional welding

Inspection standard: Visual + MT/UT on critical joints per AS/NZS 1554.1 SP Outcome

✅ AS 4991-compliant structure

✅ No design overbuild

✅ Practical weldability on-site or in-shop

✅ Full engineering sign-off and traceability Need help validating custom lifting frames or structural systems?

We combine FEA, code compliance, and practical design insight for certified, fabrication-ready outcomes.

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