Skip to content

Loose bolts on turbine engine exhaust stack

The following near miss on an offshore installation has been reported.

During high winds a 21m exhaust slack from one of the turbine engines on an offshore installation was seen to be moved abnormally. It appeared that the point of movement was at a joint halfway up the stack. Concerned that the top section might fall off, the installation was shut down and depressurised.

When scaffolding was erected and lagging removed, all 64 bolts around the joint were found to be loose and many bolts had come off – this is assumed to be due to vibration. It transpired that this part of the stack installed ten years ago had not been inspected since, while other parts of the stack were included on the maintenance schedule. Also the bolts used were not the ones specified in the design. These have since been replaced with bolts with a locking nut to prevent them from loosening during service.

This near miss highlights the need for inaccessible joints to be included in planned maintenance routines.


IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of all. The effectiveness of the IMCA Safety Flash system depends on Members sharing information and so avoiding repeat incidents. Please consider adding [email protected] to your internal distribution list for safety alerts or manually submitting information on incidents you consider may be relevant. All information is anonymised or sanitised, as appropriate.

IMCA’s store terms and conditions (https://www.imca-int.com/legal-notices/terms/) apply to all downloads from IMCA’s website, including this document.

IMCA makes every effort to ensure the accuracy and reliability of the data contained in the documents it publishes, but IMCA shall not be liable for any guidance and/or recommendation and/or statement herein contained. The information contained in this document does not fulfil or replace any individual’s or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.