PSA Norway: Dropped object could have injured workers on West Venture rig

Norwegian petroleum safety watchdog has completed its probe into a dropped object incident which happened on an offshore rig in March.

The incident happened on North Atlantic Drilling’s West Venture semi-submersible drilling rig right before midnight on March 23, 2015, while the rig was working on the Troll field in the Norwegian sector of the North Sea.

According to the Petroleum Safety Authority Norway,  a test plug belonging to a test tool for the blowout preventer (BOP) fell to the drill floor and continued through a spider work platform and the rotary table opening. It was halted after falling eight metres and hit the top of the BOP before coming to rest between the kill-line hub and the BOP frame.

The test plug weighed 90 kilograms, and its kinetic energy just before impact was estimated at 5 297 Joules. Two people were standing on the other side of the BOP frame when the incident occurred.

“Under slightly different circumstances, the dropped test plug could have caused injury to personnel.”

The PSA’s investigation has identified nonconformities from the regulations related to preparations for lowering the test tool through the rotary table/spider
planning and leadership; and compliance with the management system for mechanical handling operations.

As for the consequences, the incident caused minor material damage to the BOP flange and the test plug. No other damage was caused to material assets or injury to personnel.

However, the PSA Norway says that under slightly different circumstances, the dropped test plug could have caused injury to personnel.

“The plug had an equal likelihood of falling on the side where people were present. Its kinetic energy just before impact was sufficient to cause serious personal injury or death from a direct hit. The position of the personnel, in this case, meant they could not have suffered a direct hit, but the plug might have hit the BOP in such a way that it changed direction and thereby struck one of the people beneath the drill floor,” the PSA said.

The PSA has now asked NAD to describe how it intends to deal with these nonconformities.