Technical Review of Connector and Bolt Failures -BSEE
The Bureau of Safety and Environmental Enforcement (BSEE) released a technical review following the failure of connectors and bolts used in critical equipment. The technical review, entitled Evaluation of Connector and Bolt Failures, was completed by the bureau's Quality Control-Failure Incident Team (QC-FIT) and submitted to BSEE Director Brian Salerno.
BSEE will continue to monitor information related to the performance of connectors and bolts, and will update this technical review as new information becomes available.
Background
On December 18, 2012, while the Transocean Discoverer India was performing drilling operations at the Keathley Canyon (KC) KC-736 lease block in the Gulf of Mexico, the rig’s lower marine riser package (LMRP) separated from the blowout preventer (BOP) stack resulting in the release of approximately 432 barrels of synthetic-based drilling fluids into the Gulf of Mexico. Chevron, the designated operator, reported to the Bureau of Safety and Environmental Enforcement (BSEE) that the incident was the result of the failure of H4 connector bolts manufactured by GE Oil and Gas (formerly Vetco-Gray), on the LMRP.
Based on the initial analysis of the failure performed by Transocean, Chevron, and GE, GE sent replacement bolts for all known H4 connectors to customers worldwide. After learning of the December 18th incident, BSEE worked with GE to ensure that the company replaced any faulty bolts that were in use in equipment deployed on the Outer Continental Shelf (OCS), in a timely manner. This process resulted in the replacement of more than 10,000 bolts over a relatively short time frame and short-term disruption of related deepwater activities.
Verification of the structural integrity of a critical component like H4 connector bolts, which are currently deployed on the OCS and globally, is essential for both worker safety and the protection of the environment. Accordingly, in January 2013, BSEE tasked the Quality Control-Failure Incident Team (QC-FIT) to evaluate the possibility of additional bolt failures and make recommendations to mitigate potential risks of future failures, either domestically or internationally. BSEE charged the team, comprised of BSEE engineers and other technical personnel, with evaluating the currently available information including: (1) the Chevron/Transocean/GE root-cause analysis, (2) GE ’s connection design, manufacturing, and quality control processes, and (3) other information related to the performance of this equipment. During its inquiry, the QC-FIT was made aware of other offshore oil and gas failures related to bolts, studs, inserts and connectors, appearing to share similar contributing factors. BSEE management requested the QC-FIT to evaluate whether the causes of these other failures were related and whether evidence existed of an industry-wide issue.
The QC-FIT conducted visits with drilling contractors, equipment manufacturers, and a classification society; contacted BSEE’s counterparts in the International Regulators’ Forum (IRF); met with three operators- BP, Shell, and Chevron in the Gulf of Mexico; reviewed reports of similar incidents of bolt and connector failures in subsea environments; and researched technical documents and standards. These activities provided significant information on the material properties used in subsea applications, corrosion behaviors, manufacturing processes and protective coatings of bolts in environments similar to those of this application.
Read the full report, which includes key findings, open issues and recommendations.