Dropped object Risk Study as part of safety assessment studies is predominantly required to support the design of an onshore and offshore platform. It is to assess the risk involved in the falling object and swinging load impacts during lifting activities in industrial facilities of both onshore and offshore. The focus of the study on impacts to Platforms, structures, process equipment and subsea pipeline.
The possible lifts will be categorized per potential drop area in order to evaluate the impact energy. Some of the causes of dropped objects are mechanical failure during lifting of components, overload protection failure, using a non-certified equipment for lifting, poor inspection of critical mechanical components, inappropriate procedures, human error, high wind, & inadequate communication during lifting activities. The guidelines for the dropped object probability is based on the international guidelines / standards. The probability of dropped objects in offshore facility is divided into two categories as fall into deck and fall into the sea. The frequency of the dropped object is based on the lifting activities. The number of lifts per year is the parameter to take the probability of drop. The impact energy of the dropped object is directly proportional to the height from which the object dropped. The projected area shall be identified with the shape & angle of the dropped object.
The Methodology of Dropped Object Study procedure encloses dynamic features into the risk assessment procedure with respect to the conduction of load lifting or handling by using cranes or other lifting equipment in the oil and gas sector.
Fall energy, Ef=mgh,
where m = weight of the object in kg,
h = height at which the object is dropped,
g = gravitational acceleration (9.81m/s2).
Any Object that falls over from its initial place and has a possibility to incur injury, fatality, equipment damage and environmental damage. Dropped objects are classified as Static Dropped Object and Dynamic Dropped Object.
A Dropped Object scenario occurs where personnel injury or death, equipment damage, is caused by an Object dropping down from height. These scenarios put at risk not only the safety of personnel but also critical instruments placed in the potential impact region.
The risks caused by the dropped object need to be addressed and prevented / eliminated in order to avoid the occurrence of event. This can be done by reducing the frequency of the event, reducing the consequences of the event or a combination of both frequency and consequences.
The risk can be avoided by implementing safety management system, so that the risk associated with load lifting operations are as low as reasonably practicable (ALARP). Besides this there are other factors which can be considered to prevent Dropped Objects. They are as follows.
An object that falls from its initial position as a result of applied force is called Dynamic Dropped Object. Example; Collisions involving travelling loads or Objects.