Recommendation Date
Recipient Name
MNZ
Text
The cylinder failed at below its normal working pressure because severe external corrosion had reduced the wall thickness from 4.81 mm to 1.45 mm (about 30% of its original thickness).
The failed nitrogen cylinder and several other pressure cylinders within the stored energy system were not fit for purpose and should not have been in service.
There is an urgent need for consistent and proper standards to be developed at a global level for maintaining, inspecting, testing and, where necessary, replacing high-pressure cylinders associated with stored energy systems on board ships.
Under the applicable IMO requirements, the stored energy systems were to be examined annually for “satisfactory condition and operation”; however, the IMO did not provide any recommended minimum standards for the inspection, testing and rejection of pressure vessels that were part of a stored energy system. This resulted in different flag states having different minimum requirements for ensuring that pressure vessels remained in ‘satisfactory condition’. Some flag states had no minimum testing and rejection requirements for pressure vessels associated with stored energy systems.
On 22 November 2018 the Commission recommended that the Director of Maritime New Zealand raise through the appropriate International Maritime Organization safety committee for its consideration, the implications for maritime safety of not having adequate minimum standards for the inspection, testing and rejection of pressure vessels that are part of a stored energy system.
The failed nitrogen cylinder and several other pressure cylinders within the stored energy system were not fit for purpose and should not have been in service.
There is an urgent need for consistent and proper standards to be developed at a global level for maintaining, inspecting, testing and, where necessary, replacing high-pressure cylinders associated with stored energy systems on board ships.
Under the applicable IMO requirements, the stored energy systems were to be examined annually for “satisfactory condition and operation”; however, the IMO did not provide any recommended minimum standards for the inspection, testing and rejection of pressure vessels that were part of a stored energy system. This resulted in different flag states having different minimum requirements for ensuring that pressure vessels remained in ‘satisfactory condition’. Some flag states had no minimum testing and rejection requirements for pressure vessels associated with stored energy systems.
On 22 November 2018 the Commission recommended that the Director of Maritime New Zealand raise through the appropriate International Maritime Organization safety committee for its consideration, the implications for maritime safety of not having adequate minimum standards for the inspection, testing and rejection of pressure vessels that are part of a stored energy system.
Reply Text
To address the recommendation Maritime New Zealand intends to raise the issue with the relevant IMO body as soon as practicable, whether this is the Maritime Safety Committee, or one of its technical sub-committees. Once we are in a position to do so we will also ensure that New Zealand delegations to relevant IMO meetings are briefed to support work on the issue being progressed.
Related Investigation(s)