Overall Finding: Both the Bureau of Safety and Environmental Enforcement (BSEE) and the oil and gas industry has made important advances in improving bolting reliability for deep sea drilling operations. However, there are multiple opportunities for the industry and BSEE to work together to further enhance the safety culture and to increase fastener reliability.
The options and recommendations presented below are a reiteration of the options and recommendations that are discussed in detail in Chapters 2 through 5. In accordance with the statement of task (Appendix A), the committee developed options for the regulatory agency, BSEE, to consider for action but no recommendations. The committee has offered recommendations for the oil and gas industry.
Summary Option 6.1 is a synthesis of recommendations in the report that deal with actions that BSEE could take to guide the oil and gas industry in constructing a multi-faceted roadmap for actions that could lead to improvements in subsea bolting reliability. New regulatory action would be guided not only by the statutory requirement to determine which best available and safest technology options meet an economic feasibility hurdle. But also by working within the standards development process, by promulgating new regulations to supplement standards, or by requesting statutory changes.1
1 Bureau of Safety and Environmental Enforcement, “Statutory Requirements of OCSLA Regarding the Use of BAST,” https://www.bsee.gov/what-we-do/regulatory-safety-programs/statutory-requirements, accessed November 13, 2017.
Summary Option 6.1: BSEE could undertake the proactive role of working with the oil and gas industry to construct a comprehensive roadmap that could advance the safety of threaded subsea fasteners. The multi-faceted roadmap would contain key objectives and priorities that could be executed and implemented by the industry, much as was done in the Federal Aviation Administration’s (FAA’s) Jet Engine Titanium Quality Consortium and the U.S. Navy’s SUBSAFE efforts. Industry should have a large role in determining the priority for addressing potential improvements. The roadmap could be divided into several sections:
- Investigate bolting cluster failures using a large-scale fully instrumented flange test rig that simulates subsea conditions on fasteners in bolted joints including structural loads, environmental conditions and cathodic protection. [Option 2.9]
- Research and development of specific innovation opportunities that have the potential to significantly advance the reliability of offshore fasteners in critical service. [Options 2.2, 2.4, 5.1]
- Identification of gaps in current standards and obtaining the necessary data to guide updating the standards. [Options 2.5, 2.10, 3.1, 3.2, 3.3]
- Promotion of a strategic vision for the safety culture throughout the oil and gas industry. This would include collecting and disseminating information about fastener performance, failures, and near misses across different disciplines and organizations, and using this information to guide roadmap priorities. [Options 2.1, 2.3, 2.6, 3.4, 3.5]
Summary Recommendation 6.2 is a synthesis of the six recommendations in the report that address actions which the oil and gas industry should take in concert to improve subsea bolting reliability. The activities to implement these recommendations could be incorporated into the comprehensive roadmap activity mentioned in Summary Option 6.1.
Summary Recommendation 6.2: Actions that the oil and gas industry should take to improve subsea bolting reliability include the following:
- Establish a comprehensive methodology/program to optimize the cathodic protection (CP) practice for critical assets containing fastener metallic materials. [Recommendation 2.7]
- Review the usage of materials in contact with fasteners that are known to poison the chemical reaction of atomic hydrogen converting to hydrogen gas. [Recommendation 2.8]
- Establish a standard accepted laboratory standard test method to assess the susceptibility to environmentally assisted cracking/hydrogen embrittlement
- of bolting materials and their coatings used in offshore applications [Recommendation 2.10]
- Conduct systematic studies to assess effect of bolt designs on hydrogen embrittlement susceptibility. [Recommendation 2.11]
- Review the standards relating to bolt tensioning, both in terms of loading as a percent of yield strength and in terms of preloading technique, to minimize the probability for excessive stress on bolts operating in subsea environments. [Recommendation 2.12]
- The oil and gas industry should promote an enhanced safety culture across organizations and disciplines that is reflected in work rules and that involves encouragement at all levels of the organization to improve the reliability of subsea bolts. [Recommendation 4.1]
- Support activities related to Summary Options 6.1
Option 2.1: BSEE could convene an industry study group to investigate flange bolt design and installation standards. Options which could be considered include:
- Put a hold on requirements for industry to use more accurate torqueing equipment.
- API Spec 17D could be revised to “require” rather than “recommend” that bolts be accurately preloaded. Eliminate the term “torque” as torque has been determined to be inherently inaccurate.
- Suggest the use of a more accurate bolt pre-tensioning method for critical flange bolt preloading on all new equipment fabrication and at 5-yearly inspections. (Appendix J lists some alternative bolt pre-tensioning methods.)
- Consider commissioning engineering design studies to determine realistic tension loading safety margins for flange bolts. Such a study could initially concentrate on the preload variability that results from torqueing, however assessments of operational loading uncertainty and in-service material degradation could also be considered.
- Consider commissioning a study to evaluate the impact of a single bolt failure on overall connector reliability. This study could cover a range of flange sizes (i.e. number of flange bolts).
- Consider new and revised specifications, standards and recommended practices to be incorporated into Code of Federal Regulations (CFR) 30 section 250 based on proactive assessment of risk areas.
Option 2.2: BSEE could request an industry-led consortium with academic participants to initiate systematic studies to investigate and evaluate the environmentally assisted cracking/hydrogen embrittlement susceptibility of continuous cast and ingot cast steels. The results on continuous cast steels could also include “modern”
product produced in newer facilities and characterized with non-destructive testing techniques to assess soundness. The consortium could also evaluate alternate steel alloys and processing histories leading to improved in-service performance. The prohibition of banding to maintain product quality for subsea bolting could also be reviewed.
Option 2.3: Under the oversight of BSEE, the industry could collect data on the service conditions and performance of bolting in all critical riser/BOP applications for every deepwater drilling operation. This would include subjecting all fasteners, failed and un-failed, in these critical applications to a thorough post-operational inspection—requiring a full dimensional check and metallurgic post-mortem, with root-cause analysis being performed when the equipment did not perform according to design.
Option 2.4: The oil and gas industry should pursue technologies that offer more effective NDT inspection of bolts in situ, on the deck, and in the shop. Employment of these technologies should be made mandatory by BSEE as they have been qualified in other industries.
Option 2.5: BSEE could establish inspection requirements for un-failed bolts during the 5-year shop inspection, or could require that all critical bolts be replaced during this inspection. BSEE should also establish/require serial numbers on all critical bolts so that inspections of any specific bolt could be documented and catalogued. The results from inspections could be reported as determined by mutual agreement between BSEE and the organization performing the 5-year shop inspection.
Option 2.6: BSEE could take steps to incorporate the following API specifications and recommended practices, (in total or in part) into CFR 30 section 250 by reference to ensure that the best known maintenance practices are instituted:
- API Spec 16F, “Specification for Marine Drilling Riser Equipment”
- API RP 17G, “Recommended Practice for Completion/Worker Risers”
- API RP 16Q, “Recommended Practice for Design, Selection, Operation and Maintenance of Marine Drilling Riser Systems”
Recommendation 2.7: The oil and gas industry should establish a comprehensive methodology and or program to optimize the cathodic protection (CP) practice for critical assets containing fastener metallic materials. For current structures, CP monitoring and assessment practice should be instituted. As new
structures are designed, the industry should establish CP design requirements optimized for materials in use, based on electrochemical fundamentals. This project should evaluate the use of “low voltage” aluminum anodes currently being used by the U.S. Navy and the French Navy to reduce the risk of hydrogen embrittlement of their high-strength alloys.
Recommendation 2.8: The industry should review the usage of materials (e.g. lubricants containing sulfides) in contact with fasteners that are known to poison the chemical reaction of atomic hydrogen converting to molecular hydrogen (hydrogen gas), and identify substitute materials so that the concentration of atomic hydrogen at the metal surface is reduced.
BSEE could consider immediately prohibiting the use of sulfide-containing lubricants until such a study indicated that they can be used without enabling hydrogen uptake.
Option 2.9: The committee suggests that cluster failures be investigated by BSEE in large-scale fully instrumented flange test rig that simulates subsea conditions on fasteners in bolted joints including structural loads, environmental conditions, and cathodic polarization. These investigations are necessary to definitively establish the origins of these cluster failures and to prove the effectiveness of mitigation strategies.
Recommendation 2.10: The oil and gas industry should establish through adequate research an accepted laboratory standard test method to assess the susceptibility to hydrogen-assisted cracking of bolting materials and their coatings used in offshore applications.
Recommendation 2.11: The oil and gas industry should:
- Assess various thread designs and manufacturing methods for maximum resistance to environmentally assisted fracture.
- Conduct systematic studies to assess effect of bolt designs (including the tread geometry) on hydrogen-assisted cracking susceptibility.
- Pursue research into thread designs which could reduce the stress concentration in bolt threads.
Recommendation 2.12: The oil and gas industry should review the standards relating to bolt tensioning, both in terms of loading as a percent of yield strength and in terms of preloading technique, to minimize the probability for under or over-tensioning bolts operating in subsea environments.
Option 3.1: BSEE could leverage the results of the study at Argonne National Laboratory that is evaluating fastener standards to bring industry together in addressing detailed standards and best practices in design, materials, manufacture and operation of offshore structures.
Option 3.2: The committee endorses the Summary Recommendation 6.1 contained in the National Academy of Engineering/National Research Council 2012 report on the Macondo Well Deepwater Horizon blowout:2 “The United States should fully implement a hybrid regulatory system that incorporates a limited number of prescriptive elements into a proactive, goal-oriented risk management system for health, safety, and the environment.” BSEE could implement this Summary Recommendation.
Option 3.3: Safety critical standards and specifications could be enforced by BSEE throughout the supply chain by incorporation of such standards into the Code of Federal Regulations.
Option 3.4: The committee agrees with the BSEE 2016 QC-FIT report, Evaluation of Fastener Failures Addendum that recommended that all bolts used in critical service in US OCS waters shall be manufactured by organizations that maintain sufficient quality certifications.3 BSEE could consider fully implementing this recommendation.
Option 3.5: The FAA and U.S. Navy regulatory approach and governing authorities have elements that BSEE could tailor for their domain of interest. In some cases, additional statutory authority may be necessary.
Recommendation 4.1: The oil and gas industry should promote an enhanced safety culture across organizations and disciplines that is reflected in work rules and that involves encouragement at all levels of the organization to improve the reliability of subsea bolts. This would include:
2 National Academy of Engineering/National Research Council, Macondo Well Deepwater Horizon Blowout: Lessons for Improving Offshore Drilling Safety, Washington, D.C.: The National Academies Press, 2012.
3 Bureau of Safety and Environmental Enforcement, QC-FIT Evaluation of Fastener Failures—Addendum, QC-FIT Report #2016-04, Office of Offshore Regulatory Programs, Washington, D.C., February 2016, https://www.bsee.gov/sites/bsee_prod.opengov.ibmcloud.com/files/memos/public-engagement/qc-fit-bp-bolts-report-final.pdf.
- The creation of a dedicated organizational Human Systems stakeholder
- Attention to the individual worker and skill development through training, selection and work process design
- Company and industry-wide sharing of best practices for collecting and disseminating information about fastener performance, failures, and near misses
- Assessing gaps that could be mitigated by technology developments
Option 5.1: BSEE could take a leadership role in forming a consortium with components from industry, academia and government to evaluate the innovative concepts presented, potentially add to these, and implement those that are deemed beneficial and require little development. The oil and gas industry should have a strong role in determining the priorities of which ideas to pursue. BSEE, using the recommendations of the consortium, could also initiate research and development efforts for those innovations that may offer considerable safety advantages but are not currently available as products or systems.
Two recent BSEE Quality Control-Failure Incident Team (QC-FIT) reports4 contain recommendations that are related to the above recommendations. Table 6.1 is a summary relating QC-FIT recommendations to those contained in this appendix.
4 Bureau of Safety and Environmental Enforcement, Evaluation of Fasteners Failures—Addendum, QC-FIT Report #2016-04, Office of Offshore Regulatory Programs, February 2016, https://www.bsee.gov/sites/bsee.gov/files/qc-fit-nov-bop-bsr-bolt-report-7282017.pdf; Bureau of Safety and Environmental Enforcement, Evaluation of Connector and Bolt Failures—Summary of Findings, QC-FIT Report #2014-01, Office of Offshore Regulatory Programs, August 2014, https://www.bsee.gov/sites/bsee.gov/files/bolt_report_final_8-4-14.pdf.
TABLE 6.1 BSEE QC-FIT Report Recommendations
|QC-FIT Report||QC-FIT Recommendation||Report Options and Recommendations|
|2016a||Industry should: (1) ensure that API Specification (Spec) Q1 contains sufficient controls over second- and third-tier vendors, (2) ensure that the API monogram program provides sufficient audit mechanisms to ensure that OEMs are in full compliance with API Spec Q1, and (3) review current regulations and standards to ensure that the sections on mechanical integrity and contractor qualification are sufficiently robust.||3.1, 3.2, 3.3, 3.4|
|2016||Industry should perform a comprehensive review of industry standards related to fasteners and develop consistent guidance for ideal material property requirements for subsea fastener manufacturing. The review should also include a comprehensive analysis of manufacturing best practices and environmental service conditions for subsea fasteners.||2.7, 2.8, 2.11, 3.1|
|2016||BSEE should consider incorporating API Spec 20E First Edition, August 2012 “Alloy and Carbon Steel Bolting for Use in the Petroleum and Natural Gas Industry” into regulations to provide consistency in material property requirements for use of subsea fasteners on the OCS.||3.1|
|2016||The failure mechanism of the subsea fasteners is not fully understood. Industry and/or BSEE should perform technical studies to evaluate the combined effect of fastener material properties, coatings, and load and environmental conditions to better understand fastener performance and prevent such failures from happening in the future. It should be noted that due to the natural dissipation of hydrogen, direct evidence of a hydrogen embrittlement (HE) failure is not possible. Other possible causes of a brittle fracture of the fasteners were not evaluated, and environmentally-assisted cracking (EAC) was the likely failure mode of the fractured studs. There are well established laboratory analysis protocols to study the brittle fracture of steel. Micro-cracks were also observed at the root of the threads in some of the samples analyzed, which would be due to inadequate heat treatment procedures that contributed to premature failure of the fasteners under normal loading condition.||2.9|
|2014b||Improve industry standards||2.10|
|2014||Initiate joint industry research initiatives||2.2, 2.4, 5.1|
|2014||Promote failure reporting||2.3, 2.5, 4.1|
a Bureau of Safety and Environmental Enforcement, Evaluation of Fasteners Failures—Addendum, QC-FIT Report #2016-04, Office of Offshore Regulatory Programs, February 2016, https://www.bsee.gov/sites/bsee.gov/files/qc-fit-nov-bop-bsr-bolt-report-7282017.pdf.
b Bureau of Safety and Environmental Enforcement, Evaluation of Connector and Bolt Failures—Summary of Findings, QC-FIT Report #2014-01, Office of Offshore Regulatory Programs, August 2014, https://www.bsee.gov/sites/bsee.gov/files/bolt_report_final_8-4-14.pdf.