CROSS Safety Report
Blind bolt failure on offshore platform
This report is over 2 years old
A reporter describes how there was a failure on an offshore platform of a 20t winch base under load testing.
Key Learning Outcomes
For civil and structural design engineers:
Connections can often be the weak link in structures and attention to detail is required
If you are uncertain with technical information provided by the fixing manufacturer, seek clarification from their technical support team
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A reporter describes how there was a recent failure on an offshore platform of a 20t winch base under load testing. There were no injuries, but significant business impact. Failure occurred in tension of a holding down arrangement of blind bolts which were of the locking pin/cam variety. There were three primary causes of the failure, two of which related to competence and checking of calculations.
However, the third cause was concluded to result from the presentation quality of the downloadable information on the manufacturer’s website, which led to confusion by the designer between ultimate and allowable capacities. The failure also raised concerns over the application of blind bolts in tension where failure is rapid and catastrophic, with no ductile warning of overload.
Expert Panel Comments
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Details on the cause of failure are not known but clarity of information on manufacturers’ websites is a concern. The web is unregulated, and it requires experience to write technical information unambiguously and to include all relevant material; at the very least this requires input from a competent structural engineer.
However, it is for users to ensure they are satisfied with the data presented and for manufacturers to ensure they have correctly presented their material: their reputation will depend upon it. Issues around blind bolts have been raised previously to CROSS. You can search for safety information on ceilings on the CROSS website. One of the aims of CROSS is have such data available so that future failures of the same type can be avoided.
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