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Jun 23, 2023

Lessons learned from near

After looking into circumstances surrounding a high-potential, near-miss

After looking into circumstances surrounding a high-potential, near-miss fatality during crane operations on the Outer Continental Shelf (OCS), the U.S. Bureau of Safety and Environmental Enforcement (BSEE) has come up with recommendations for oil and gas operators and contractors to assist in preventing such incidents in the future.

In a safety alert, BSEE explained that a 700-pound crane headache ball fell 24 feet while conducting crane operations during a decommissioning/well abandonment activity, crashing to the deck less than two feet from one of the riggers. The undisclosed operator reported this high-potential, near-miss fatality to BSEE on 20 September 2022.

At the time of the incident, the crane was moving a 400-pound well cap from one well access panel to an adjacent panel when a wedge socket on the auxiliary line snagged on the flange of a C-channel located at the edge of the platform's rig deck. The lift required running the crane's auxiliary line within inches of the edge of the platform rig structure.

With the wedge socket above the headache ball snagging on the C-channel flange that ran across the length of the edge of the deck, this snag temporarily held all the weight of the load and rigging, resulting in a false reading on the auxiliary winch. While the load cell sending a weight signal to the operator was located below the snagged wedge socket, the crane operator did not detect that the auxiliary winch was no longer holding the weight of the load.

According to the U.S. regulator, the blind lift was being directed using radio communications by a rigger standing on the pipe deck, thus, the rigger had a clear view of the load, line, pedestal crane, and crane operator and his location put him approximately 30 feet from the load line.

However, the rigger did not realise that the line had snagged on the C-channel and continued giving directions to keep lowering the well cap. As the load cell was positioned below the snag, there was no change in the load signal, even though the weight of the load was now being supported by the C-channel and not the auxiliary winch.

The BSEE explains that the load cell works by converting a specific type of mechanical force – typically tension, torque, compression, or pressure – into an output signal, which is then transmitted via a load cable to the scale's indicator where the precise weight can be measured and read by the crane operator.

Furthermore, as the rigger did not see any movement, he repeated a request to lower the load. On the other hand, the crane operator could not see the winch drum behind the crane cab, thus, he did not see that the load was not moving and responded that he was still lowering the load.

With the crane operator continuing to unwind the auxiliary line at the winch drum, the wedge socket slipped off the flange of the C-channel, releasing the snag and the 700-pound headache ball fell 24 feet, striking the deck less than two feet from one of the riggers guiding the load. After the incident, a third party inspected the crane, replaced a small three-inch pin for the hook latch, and the crane was placed back in service.

The contributing factors to this incident, identified by the U.S. regulator, reveal that the rigger and crane operator should have noticed the auxiliary winch was no longer detecting the weight of the load as the engineering controls – weight indicator – provided an inaccurate representation of the crane operator of weight on the winch due to wedge socket snagging on the flange of the C-channel above the load cell.

Furthermore, the BSEE points out that the crane operator and rigger failed to recognise something was wrong after repeated requests asking to lower the load and receiving the response that the line was being lowered and not seeing any movement in the load position.

In addition, the rigger did not check the path of the auxiliary line for potential snags while the work team should have noticed the potential hazards of working close to the C-channel at the edge of the platform rig. The regulator states that the work team should have recognised the potential snag points. While no formal risk assessment was conducted, a review of the task was performed.

With this at the forefront, BSEE recommends to operators and contractors to ensure a secondary device – weight indicator, camera – is accessible to detect any slack on the load line, identify all potential wireline contact points and include them in worksite instructions, risk assessments, and toolbox talks.

When working close to the equipment and facility structures, the U.S. regulator advises operators and contractors to identify potential contact and snag points and incorporate appropriate mitigation actions, including placing additional spotters at potential contact or snag points.

Additionally, the regulator recommends discussing what key controls are in place to remove oneself and one's team members from the potential line of fire, which is the zone within a work area where there is a risk of serious injury from machinery or equipment.

BSEE further underscores that operators and contractors should ensure all operations and contract personnel involved in lifting operations attend and participate in a pre-job meeting/toolbox talk and document.

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