Last reviewed 4 June 2021
The Health and Safety Executive (HSE) has issued a safety alert after what it described as the catastrophic failure of a marine loading arm (MLA).
MLAs are commonly used throughout UK ports and jetties to load and unload liquids and compressed gas products from river barges, ships and tankers.
Evidence obtained during the HSE investigation of a failed MLA revealed concerns that not all components were being suitably inspected and maintained due to problems accessing the highest pivot joint.
“The lack of lubrication of this greased joint presents a serious risk of the joint failing with the potential for complete collapse of the arm,” HSE explained, “leading to possible death, serious injury or damage to process equipment and subsequent loss of containment.”
Anyone using or servicing MLAs should check, review and identify inspection and maintenance work required by the manufacturer and industry guidance.
They should plan how the work will be conducted (including the parts that are difficult to access) and ensure it is completed. Records should be kept and outstanding actions followed up.
The eight-inch nominal bore, hydraulically operated MLA involved in the incident had been in service for 11 years and had been regularly maintained by various recognised industry contractors.
It had a rigid link pantograph balancing system with independent primary and secondary counterweights linked to the inboard and outboard arms.
However, it failed as it was being manoeuvred towards a ship manifold for connection. A section of the MLA fell backwards onto a jetty handrail narrowly avoiding live plant and pipework on an upper-tier COMAH (Control of Major Accident Hazards) establishment.
Investigation found that a failed pantograph pivot pin led to the resulting collapse of the arm. The immediate cause of the failure was from corrosion of the bearing that led to a complete fracture, emanating from the circumference.
The underlying causes were inadequate inspection and maintenance practices which had led to the corrosion. See https://www.hse.gov.uk/safetybulletins/marine-loading-arm-failure.htm for full details of the alert.