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CROSS Safety Report

Blind bolt failure on offshore platform

Report ID: 170 Published: 1 January 2010 Region: CROSS-UK

This report is over 2 years old

Please be aware that it might contain information that is no longer up to date. We keep all reports available for historic reference and as learning aids.


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

Full Report

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The Full Report below has been submitted to CROSS and describes the reporter’s experience. The text has been edited for clarity and to ensure anonymity and confidentiality by removing any identifiable details. If you would like to know more about our secure reporting process or submit a report yourself, please visit the reporting to CROSS-UK page.


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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Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

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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