ASSDA Member and Accredited Fabricator Aflex has played a pivotal role in supporting the seismic resilience of one of New Zealand’s most important cultural infrastructure projects – the new Archives New Zealand building in Wellington.
Engaged by Motion NZ, Aflex was tasked with designing and delivering seismic bellows assemblies for the 10-storey archival facility at the corner of Aitken and Mulgrave Streets. Built to preserve more than 12 million irreplaceable documents and cultural taonga, the new building sits on a major fault line, necessitating an innovative approach to seismic protection.
Engineering a stainless steel solution
With space constraints for mechanical services and the requirement to accommodate ±500 mm axial movement in all directions (X, Y, Z), the project presented a unique and complex design challenge. Traditional bellows systems would not withstand this scale of movement while remaining stable under operational pressure.
The solution? Aflex designed bespoke multi-element, double gimbal pantograph bellows assemblies – a sophisticated, self-supporting system built to handle high-magnitude seismic movement with precision and durability.
Over 1,800kg of laser-cut plate, pipe, flanges and fittings were used in the fabrication of the bellows assemblies, with materials supplied by ASSDA Member Stirlings Performance Steels. The stainless steel sheet for the bellows elements were supplied by ASSDA Member Midway Metals. Grade 316 stainless steel was chosen for its superior corrosion resistance and mechanical properties, delivering a projected service life exceeding 20 years. Its high elongation values are critical for the hydraulic forming of the bellows elements, ensuring proper convolution profiles without risk of failure.
Conventional bellows systems typically involve one or two elements and standard hardware such as tie rods or gimbal rings. In contrast, this project’s assemblies featured multiple bellows elements (typically eight) arranged centrally, single gimbals on each end, and pantograph arms connecting the central bellows.
The pantograph system is key to managing overall stress within the bellows assembly. As the building shifts during a seismic event, the pantograph evenly distributes movement across each bellows element, preventing overstressing of any single component and enhancing both longevity and reliability. Each arm is connected via pivot points and linked to single gimbals at either end, enabling the assemblies to accommodate multidirectional displacement.
To verify performance, Aflex used Fusion 360 software to model dynamic movement and ensure hardware clearance, and EJMA (Expansion Joint Manufacturers Association) design calculations to assess bellows stress, spring rates, and cycle life against industry benchmarks. The result was a precision-engineered solution, unique in complexity and scale – considered among the most intricate gimbal-pantograph assemblies ever manufactured in Australia.
Built to last, built to perform
Aflex’s commitment to quality is embedded in every weld. Their Sydney-based facility operates with custom bellows-forming equipment and leading-edge, energy-efficient TIG and MIG welding systems. Certified to ISO 9001 and ISO 45001, Aflex employs a fully digital system across all manufacturing processes and utilises advanced welding fume extraction technology. All welding parameters are recorded digitally – including operator, weld speed, current, voltage, and filler materials – supporting a paperless workflow and ensuring full traceability and unmatched quality assurance.
Through stainless steel expertise and engineering innovation, Aflex has demonstrated the critical role of local design and fabrication capability in delivering world-class infrastructure that is safe, sustainable, and built to last.
This article was featured is Australian Stainless Magazine 82.
