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Catastrophic failure of marine loading arm

Health and Safety Executive - Safety alert

Department Name:
Chemical, Explosives, Microbiological Hazards Division 

Bulletin No:
CEMHD1-2021

Issue Date:
2021

Target Audience:

All users of marine loading arms, as well as suppliers and servicing companies

Industries:

  • Export and import of dangerous chemicals – Prior Informed Consent (PIC)
  • Offshore oil and gas
  • Ports and logistics

Topics – Carriage of dangerous goods, Control of Major Accident Hazards Regulations (COMAH) Strategic forum, Fire and explosion.


Key Issues:

Marine loading arms (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 an 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, 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. 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 should be followed up.

Introduction

Marine loading arms (MLAs) are used to transfer material from ship to shore. They are often located in arduous environments and are therefore subject to degradation. An incident where lack of lubrication on a pivot joint caused a catastrophic failure resulted in the collapse of the arm. This highlighted the importance of adequate inspection and maintenance even where access is difficult.

This safety alert is aimed at users and companies that service MLAs to ensure they carry out suitable and sufficient inspection and maintenance to help avoid similar incidents.

Background

The 8-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.

Figure 1 below identifies the location of the failed pivot pin.


Failed pin location
Figure 1: The location of the failed pivot pin

The MLA 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 establishment.


Loading arm colapsed onto railing
Figure 2: A section of the MLA fell backwards onto a jetty handrail

Investigation found that a failed pantograph pivot pin led to the resulting collapse of the arm.


Detail of the failed pivot pin
Figure 3 The failed pantograph arm pivot pin

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.

There was no convenient means of accessing the pivot pin for inspection and maintenance. As a result, it had not been lubricated during servicing by several different contractors.

Industry guidance provides information on maintenance and inspection requirements including lubrication. Further details can be found in the 'References' section below.

Action required

The failure to properly inspect and maintain an MLA could result in a serious risk of a joint failing, allowing the pantograph arm to fall – with the potential of causing death, serious injury or damage to process pipework.

A review of MLA designs suggests the problem of access to all parts requiring maintenance may not be specific to one manufacturer.

Anyone using or servicing MLAs should use a structured management system to ensure they have adequate inspection and maintenance preventing a possible catastrophic failure.

Examine what is in place and identify areas that need to be addressed (Plan)

Identify areas at risk and prioritise accordingly (Do)

Evaluate the work (Check)

Review your performance (Act)

Relevant legal documents

References

Further information

Health and Safety Executive, Redgrave Court, Merton Road, Bootle, Merseyside, L20 7HS

General note

Please pass this information to a colleague who may have this product/equipment or operate this type of system/process.

2021-06-15