Marine Fenders: Distinction between Fender Damage and Failure due to unsafe practices.
CASE STUDY: Chhara LNG Terminal
It was reported in the media and consequent comments in LinkedIn thereafter by interested parties that the unloading of Vessel Maran Gas Mystras was abandoned due to fender failure. Whereas the fenders were supplied by IRM meeting and exceeding design Energy / Reaction Characteristics and specification provided by the Owner / Consultant. The fenders were inspected and load deflection tested in the presence of Third Party Inspection Agency and Client Representative. All stringent quality protocol was followed for both material and workmanship.
The sequence of events culminating into the damage of the fender can be summarized as follows:
- There was no effective breakwater in place to control the extreme swell of the sea.
- Due to the onset of monsoon, the sea was more turbulent with swell, currents, and winds.
- This did not allow the vessel to achieve mooring and it was continuously pitching, rolling and swaying.
- Despite this, the vessel was kept at the mooring dolphin, though the velocities of such impacts have exceeded three times the design velocity from 0.1 m/s to 0.32 m/s.
- There was continuous cyclic loading on the fenders of several thousand compressions and retractions.
- Generally, as per the international standards the fenders are conceptualized for hundred berthing operations in a year where in this instance considering a cycle time of 30 seconds fenders were compressed several thousand times.
When the velocities are more than three times, the berthing load works out the square of the above resulting in to nine times of the berthing load, hence the incident and outcome can be concluded as follows:
The fenders were damaged due to the continuous cyclic berthing exceeding the design velocity many times by two times or three times. Since the mooring could not be achieved, the vessel would have drifted away and came back at high pitching velocity, loading the fender both axially and laterally and dragging the fenders up and down due to the swell of the sea.
The climate deteriorated from the 3rd day onwards up to the 7th day and no efforts were undertaken to take out the vessel from the berth. This may have resulted in the damage of 5 loading arms too.
It is imperative that no fenders can withstand such abuse at such high velocity and such a small cycle duration resulting in several thousand compression and retraction in 5-6 days.
We, at IRM, are proud to have manufactured and supplied such good fenders of unparalleled quality which has prevented a major accident damaging both the vessel and the berth.