CROSS Safety Report
Risk of failure of untested vibration isolators with seismic restraint
A reporter found apparently counterfeit copies of devices used to protect and isolate mechanical equipment from seismic vibration. These copies are being marketed as original equipment and appear identical to the original brand. They are being supplied with test data for seismic restraint from the manufacturer of the genuine product.
The reporter notes that, if the performance of a vibration isolator has not been tested under appropriate conditions, there is a significant risk the equipment will fail when it is most needed. This could result in catastrophic failure of a critical life-safety system.
Key Learning Outcomes
For all design engineers:
- Ensure that, if specifying a non-structural product where an equivalent is permitted, the specification should state the 'product or an independently certified approved equivalent'
For certifying engineers/building authorities:
- Conduct inspection on site to ensure the non-structural product, or an independently certified approved equivalent, has been installed and has authentic paperwork to support its installation
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A reporter found apparently counterfeit copies of devices used to protect and isolate mechanical equipment from seismic vibration. The copies are being supplied with test data for seismic restraint from the manufacturer of the genuine product and look identical to the original brand except for some small differences between models which would only be identified by a specialist.
Vibration isolators are typically installed under chilling equipment, diesel generators, and other mechanical plant and equipment used for life-safety systems (e.g. in hospitals). The reporter is concerned purchasers may be unaware they are not receiving genuine products and may install those products to protect equipment in their projects.
There is a significant risk the equipment will fail when it is most needed if the performance of a vibration isolator from seismic restraint has not been tested under appropriate conditions. This could, depending on the importance level of the structure, result in catastrophic failure of a critical life-safety system.
In the reporter's opinion, independent third-party testing must be undertaken to ensure the adequacy of systems for vibration control and isolation under seismic conditions.
Expert Panel Comments
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This report is of particular interest in that it deals with fixings to equipment considered to be in the category of non-structural building components.
In their keynote address, Seismic Design of Nonstructural Building Components: The New Frontier of Earthquake Engineering, for the 2020 Australian Earthquake Engineering Society Virtual Conference, Prof. A. Filiatrault of the School for Advanced Studies IUSS Pavia, Italy, points out that in typical cases:
'the investment in non-structural components and building contents is far greater than that of structural components and framing'. Moreover, since 'damage to non-structural components occurs at seismic intensities much lower than those required to produce structural damage, … in many past earthquakes losses from damage to non-structural components have exceeded losses from structural damage'.
Therefore, even if the structure survives a seismic event relatively intact, 'failure of architectural, mechanical or electrical components can lower the performance level of the entire building system'. Furthermore, 'the failure of non-structural components can become a safety hazard or can hamper the safe movement of occupants evacuating buildings, or of rescue workers entering buildings'.
It is noted that, while the Australian Standard relating to earthquake loading (AS1170.4) nominates requirements for design restraint of non-structural elements, structural design engineers generally exclude responsibility for such details on the basis that they are outside of scope. A contractual risk assessment identifying which party is ultimately responsible for such devices should be a consideration for the Contract Manager and Client body. It also raises questions outside the contractual framework such as reliance, whether there was an objectively real risk of a foreseeable consequence and a risk assessment of the potential severity and magnitude of the consequence that might have to be taken into account. In the paper quoted above, the author proposes a separate appointment of a specialist 'non-structural coordinator' to fulfil this role.
In the particular case raised by the reporter, it would appear seismic restraint details have been nominated by the services designer by virtue of the particular equipment specified – equipment that, if supplied as nominated, would be provided with the relevant test certificates. However, the reporter has suggested that counterfeit copies of the equipment may have been supplied, along with test certificates pertaining to the genuine equipment. This raises the issue of fraud, misrepresentation and non-compliance regarding the installation of potentially untested equipment, along with other risks.
In such a situation, the relevant parties to the Contract should consider whether misleading or deceptive conduct, or even fraudulent activity, has occurred and whether they should report it to the relevant regulators, statutory authorities (e.g. SafeWork NSW, WorkSafe QLD/VIC, WorkSafe NZ, etc) and/or the manufacturer of the original equipment for further action.
Furthermore, the practice often adopted of specifying 'product xx or equivalent' could be better served by specifying instead 'product xx or independently certified approved equivalent' so that a measure of review is introduced.
Another important implication that comes from this report is the need for inspectors to know first-hand what measures suppliers have taken to differentiate their products in the marketplace and action taken to verify compliance on site. This report demonstrates that simply viewing the relevant paperwork may not be a suitable substitute for hands-on verification.
Unfortunately, this is not an isolated incident and an earlier CROSS Alert “Anomalous documentation for proprietary products” published in February 2013 noted that there had been a number of instances reported to CROSS where certification accompanying proprietary products had stated compliance with standards or specified requirements, but the products were found not to be in accordance with those specifications. On several occasions, this has led to premature structural failure of the components at loads well below the intended design capacity.
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