Dropped Object Study

A Dropped Object (DO) study, usually conducted in part with other risk assessment studies, is predominantly required to support the design of onshore and offshore facilities. It is undertaken to assess the hazards and risks involved in potential falling objects and swinging load impacts during lifting activities in industrial facilities. Typical studies involve impacts to onshore and offshore platforms, subsea pipelines and flowlines, structures and process equipment.

Method of DO Study

The methodology for conducting DO studies is very similar to that of conducting Quantitative Risk Assessment (QRA) studies, ultimately determining the hazards and resulting risk associated with the activity/process in question. However, not all fallen objects or swinging loads will result in perforation of the equipment or facility under review, hence the impact energy of such fallen objects must be determined. This will ultimately decide if such hazardous events can occur and if so, in what ways can this be mitigated in order to avoid the occurrence of the event. 


As a minimum, the following information would be required to conduct the study:

– Existing PHA / HAZID / HAZOP report

– Consequence Analysis Models

– Platform / pipeline / equipment layout drawings

– Type and frequency of lifts, including movable object data (weight, size, etc.)

– Lift Plan, Crane and Supply Boat movements

Based on the project requirements, additional information may be required. This will be highlighted within the Terms of Reference (ToR).

On award of the study ES will issue a project ToR. This will highlight the assumptions that will be made in the study. It will also include the methodology that will be utilised as well as any further information required from the client.
Upon acceptance of the ToR, ES will conduct the analysis and prepare a DOS report. The report will describe the facility, the scope of work, include a detailed methodology, the potential frequency of dropped objects and the consequence shall be assessed. Overall risk evaluation will be carried from the results.

ES have conducted several DOS for clients around the world. ES can also conduct the preceding consequence analysis, as well as other risk analyses such as QRA’s to quantify the total risk to the facility. For more information, or to discuss your needs for conducting a DOS, please contact us using the form below or email [email protected]