[US GOM] Transocean Deepwater Pontus Dropped BOP

escveritas
Site Admin
Posts: 3186
Joined: Sat Aug 29, 2020 5:40 am
Location: Singapore
Contact:
Singapore

[US GOM] Transocean Deepwater Pontus Dropped BOP

Unread post by escveritas »

On February 27, 2021, an incident occurred onboard the Transocean Deepwater Pontus working for Shell Offshore Inc. Drilling operations were being conducted at Walker Ridge Block 508 OCS-G 17001 Well #016. The Subsea Supervisor was in the process of tracking the Blow Out Preventer (BOP) gantry crane from the starboard side setback area when a loud “pop” was heard and the operation was stopped. He noticed the encoder pinion and shaft assembly had parted on the crane and fell 72 feet to the transporter deck below. No injuries were reported and an onsite investigation was
initiated.

On February 27,2021, the Subsea Supervisor needed to position the BOP gantry crane to align the starboard auxiliary winch over the spare subsea BOP stack to install a coflex conduit. A Toolbox Talk and the procedure to move the BOP gantry crane was signed by all involved subsea crew members. The Subsea Supervisor ensured that the proper rigging was in place and the travel path was clear of obstructions. The Subsea Supervisor maneuvered the BOP gantry crane remotely from the Lower Marine Riser Package (LMRP) level from the starboard to port side, to align the auxiliary winch over the BOP to install the conduit. While operating the crane, a loud “pop” was heard, and the subsea crew called a Time Out for Safety (TOFS) to investigate. The
crew noticed the encoder pinion and shaft assembly came apart and fell 72 feet to the BOP transporter cart below. No personnel were in the area due to restricted access under the Red Zone Management Policy. The encoder pinion is made of teflon and coupled with the shaft assembly weighed approximately 2 pounds. The Subsea Supervisor notified the proper personnel about the incident and was instructed to return the gantry crane back to the starboard setback area for inspection.

The scope of work to be performed was to move the BOP gantry crane from the starboard setback area approximately 20 feet to the port side to align the starboard auxiliary winch over the BOP in order to assist installing a coflex conduit line. The Subsea Supervisor proceeded to operate the gantry crane remotely from the LMRP deck level when he heard a strange noise and immediately stopped the movement of the crane to investigate. It was discovered that the 2-pound teflon pinion broke off the encoder shaft assembly on the gantry crane and fell approximately 72 feet to the BOP transporter deck located in the moonpool area. The gantry crane was not performing a lift or bearing any weight but simply traversing from starboard to port. The encoder is mounted vertically on the BOP gantry crane and its function is to track the crane’s location as it travels. An electric cable sends a signal regarding the crane’s position which penetrates the encoder through a top cable gland. Over time, the top cable gland allowed water to settle and penetrate the encoder causing corrosion. This extensive corrosion caused deterioration to all the connecting points that held the pinion and shaft assembly together. When the gantry crane began to move, the shaft assembly snapped and the pinion fell from the bottom of the encoder, which did not have a secondary retention device.
Post Reply

Return to “Health, Safety and Environment”

Who is online

Users browsing this forum: No registered users and 3 guests