201003 Chemical cargo hose rupture
Chemical cargo hose rupture
MARS Report 201003
A chemical tanker was loading a cargo of paraxylene simultaneously into two tanks. To facilitate this, a jumper hose was inserted between the manifold connections of the two tanks on the offshore side manifold. Soon after the change of watch at midnight, the deck watch rating reported a minor (pinhole) leak on the jumper hose which rapidly developed into a major rupture. He immediately activated the shore emergency shut down (ESD) device. The terminal was advised of the situation, confirmed that the shut down had been effective, and the authorities and company were informed about the incident. No abnormal manifold pressures were noted at any time prior to or at the time of the hose failure.
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Figure 5: View of hoses stowed on catwalk showing corrosion and |
Figure 6: View of rupture on cargo jumper hose
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As a result of the hose failure, some 100 litres of cargo spilled into the manifold drip tray and approximately 20 litres overflowed on to the main deck. The cargo quickly solidified as the ambient temperature was below the melt point of the cargo and no cargo was lost overboard.
Root cause/contributory factors
Inadequate SMS procedures for proper pressure-testing of cargo hoses. However these hoses had been tested as per the practice that existed at the time of testing;
Inadequate SMS procedures for physical examination of hoses prior to use. The jumper hose's outer coiled wire sleeve was evidently rusty and it had been stowed for a prolonged period in an exposed location on the catwalk;
There was evidence that the use of rope slings to lift the jumper hose in the past had probably caused the coiled wire sleeve to be displaced, causing the hose to kink in places. In addition, the hose sling or bun was not used properly to distribute the load more evenly over the width of the sling;
Improper maintenance – the procedure of flushing of the hose with fresh water and drying was not followed properly after previous cargo operations;
Exposure to elements – the jumper hose was not covered to protect against sea water / sun which could have accelerated general deterioration;
Improper length – the jumper hose was probably longer than optimum length and the resulting sharp nip resulted in kinking of the hose.
Corrective/preventative actions
Following the failure of the hose, all the other hoses were hydraulically pressure-tested. During the test, one more cargo hose developed a pinhole leak; this was disposed of ashore. Additionally, some hoses were also landed for further testing and certification.
Recommendation to use only jumper hoses of optimum length.
All hoses supplied subsequently were equipped with permanent hose handling slings.
Suitable amendments have been made to the company SMS.
Information was being promulgated to the fleet by way of a safety bulletin to avoid a recurrence; it was also shared with the industry.