NTSB Safety Recommendation P-22-006

NTSB safety recommendation P-22-006.

TO ENBRIDGE, INC.: Disqualify and require remedial training and requalification of the covered task(s) whenever an employee does not follow procedures when responding to an emergency shutdown, rupture, or other abnormal operation.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 2022-09-14

Adopted Date: 2022-08-15

Overall Date Closed: 2023-03-30

Synopsis: On August 1, 2019, at 1:23 a.m. local time, an Enbridge Inc. (Enbridge) 30-inch natural gas transmission pipeline ruptured in Danville, Kentucky, releasing about 101.5 million cubic feet of natural gas that ignited. The accident resulted in 1 fatality, 6 injuries, and the evacuation of over 75 individuals in the Indian Camp Subdivision. Five residences were destroyed by resulting structure fires, and an additional fourteen were damaged. A nearby railroad track was also damaged, and over 30 acres of land were burned.

Probable Cause: The National Transportation Safety Board determines that the probable cause of the August 1, 2019, rupture of an Enbridge Inc. natural gas transmission pipeline and resulting fire was hydrogen-induced cracking at the surface of Line 15 in an area of damaged coal tar enamel coating resulting from a 2014 gas flow reversal project that increased corrosion rates and hydrogen generation. Contributing to this accident was Enbridge’s integrity management program, which did not accurately assess the integrity of the pipeline or estimate the risk from interacting threats.

Ntsbnumber: PLD19FR002

Report Number: PIR-22-02

Addressee Name: Enbridge, Inc.

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 2023-03-30

Addressee Organization Type: P-Private Industry

Communication Date: 2022-09-14

Communication Type: Transmittal Letter

Communication Contents: This letter provides information about the National Transportation Safety Board’s (NTSB) August 15, 2022, report Enbridge Inc. Natural Gas Transmission Pipeline Rupture and Fire, Danville, Kentucky, August 1, 2019, NTSB/PIR-22/02. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov. As a result of this investigation, we identified the following safety issues: • Nonconservative assumptions used to calculate potential impact radius. • Incomplete evaluation of the risks caused by a change of gas flow direction. • Limitations in data analysis related to the 2011 in-line inspection. • Operators’ potential for incomplete assessment of threats and threat interactions. • Missed opportunities in training and requalification practices at Enbridge. Accordingly, the NTSB makes the following safety recommendations to the Pipeline and Hazardous Materials Safety Administration. Additional information regarding these recommendations can be found in the noted sections of the report. • Revise the calculation methodology used in your regulations to determine the potential impact radius of a pipeline rupture based on the accident data and human response data discussed in this report. (P-22-1) (See section 2.3) • Advise natural gas transmission pipeline operators on (a) the circumstances of this accident; (b) the need to evaluate the risks associated with flow reversal projects; and (c) the impacts of such projects on hydrogen-induced cracking. (P-22-2) (See section 2.4) • Advise natural gas transmission pipeline operators of the possible data limitations associated with hard spot magnetic flux leakage in-line inspection tools and analyses used in hard spot management programs and reinforce the need to follow industry best practices when conducting in-line inspection data analysis. (P-22-3) (See section 2.5) The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendations by number (Safety Recommendations P-22-1, -2 and -3). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response. From the pipeline investigation report (PIR-22-02), "Enbridge Inc. Natural Gas Transmission Pipeline Rupture and Fire, Danville, Kentucky, August 1, 2019." Published on September 14, 2022. 2.7 Training and Requalification Practices On May 8, 2019, an emergency shutdown occurred at the Danville CS. During this emergency shutdown, the station operator demonstrated a fundamental lack of knowledge of station operations when he failed to use the SCADA graphics to troubleshoot the problem and closed a valve irrelevant to the event. After this incident, the station operator was not disqualified or requalified for any covered tasks nor required to take remedial training. On August 1, 2019, the same station operator was on duty when the rupture occurred. After viewing the fireball caused by the rupture and receiving a call from the gas control center, the station operator did not refer to the Stanford Area Emergency Response Plan, which listed the specific valves that required closure for isolation, and failed to isolate Line 15 at the station until the area supervisor directly instructed him to close valve 15-393. Enbridge employees are required to follow the Stanford Area Emergency Response Plan in the event of an emergency. Valve 15-393 took less than 4 minutes to operate, but it was not closed until about 16 minutes after the rupture. The Danville CS on-duty station operator’s lack of knowledge of emergency response procedures resulted in a delay in the closure of valve 15-393. This delay increased the volume of gas released, which increased the duration and intensity of the fire. The NTSB concludes that had Enbridge disqualified, requalified, or provided remedial training to the Danville CS operator after he displayed a fundamental lack of knowledge during the May 8, 2019, emergency shutdown, the operator’s closure of valve 15-393 during the August 1, 2019, rupture may not have been delayed, potentially reducing the volume of gas released. Therefore, the NTSB recommends that Enbridge disqualify and require remedial training and requalification of the covered task(s) whenever an employee does not follow procedures when responding to an emergency shutdown, rupture, or other abnormal operation.

Addressee Organization Type: P-Private Industry

Communication Date: 2023-03-31

Communication Type: Official Correspondence

Communication Contents: -From Garrett Wilkie, Director Operational Excellence Enbridge GTM- Engineering and Asset Management, Enbridge, Inc.: Enbridge Inc. (Enbridge or the Company) appreciates the National Transportation Safety Board’s (NTSB or the Board) March 30, 2023 letter classifying Enbridge’s actions performed in response to the above-referenced recommendations issued by the NTSB. Footnote: On September 14, 2022 the NTSB issued recommendations P-22-4, P-22-5, and P-22-6 to Enbridge, concerning the NTSB’s August 15, 2022 Pipeline Investigation Report on the rupture of natural gas pipeline, Line 15 on Enbridge’s TETLP pipeline system that occurred in Danville, Kentucky on August 1, 2019. The recommendations are associated with the NTSB’s investigation of the rupture of natural gas pipeline, Line 15 on Enbridge’s Texas Eastern Transmission, L.P. (TETLP) pipeline system that occurred in Danville, Kentucky on August 1, 2019. The NTSB determined that Enbridge’s actions performed in response to recommendations P-22-5 and P-22-6 satisfy the Board’s recommendations and classified them as “Closed-Acceptable Action.” With respect to recommendation P-22-4, the NTSB determined that the actions outlined by Enbridge may satisfy the recommendation, once completed, and classified it as “Open Acceptable Response.” Enbridge submits this update to its December 13, 2022 letter to confirm completion of outstanding actions associated with P-22-4. At the time of its December 13, 2022 letter, Enbridge was finalizing (1) a third party review of historical operating data on TETLP Line 15 and (2) implementing changes associated with Enbridge’s internal management of change process (MOC), a part of Enbridge’s integrated management system (IMS) consistent with the American Petroleum Institute’s Recommended Practice (RP) 1173, Pipeline Safety Management Systems. Below is a summary of the reviews that have now been completed and procedural revisions that have been implemented. 1. Third Party Review of Historical Operating Data: Enbridge engaged third party experts to conduct a review of historical operating data on TETLP Line 15 since before the flow reversal projects began in 2014 to the present for any impacts on corrosion control effectiveness. The historical review integrated data from 2010 to 2022 on Line 15 to review cathodic protection (CP) levels and pipeline coating effectiveness through evaluation of annual survey data, CP ground bed and rectifier current output history, supplemental CP ground bed installations, compressor discharge temperatures in both flow direction, and corrosion in-line inspection data. Other than what the NTSB identified in its Pipeline Investigation Report (PIR-22/02), there has not been any indication that the flow reversal project adversely impacted corrosion control equipment effectiveness. Enbridge concluded that revisions to the Gas Transmission and Midstream (GTM) integrity management plan (IMP) are not warranted as a result of this historical data review. Footnote: Enbridge GTM includes pipeline transmission systems located in the U.S. and Canada where operated by Enbridge or its subsidiaries. See https://www.enbridge.com/about-us/natural-gas-transmission-and-midstream 2. MOC Process: Enbridge completed a review and revision of its program level processes in alignment with the IMS MOC process requirements and incorporated consideration of the NTSB’s recommendation. Specifically, Enbridge identified certain areas of improvement within the MOC process and implemented associated revisions to account for adequate MOC reviews for potential impacts to integrity performance and integration into ongoing integrity assessment planning of major projects, including gas flow reversals. Consistent with its goal of continuous improvement, Enbridge also regularly incorporates appropriate updates to these processes based on lessons learned and when implementing new rulemakings. With this update, Enbridge’s entire Gas Transmission and Midstream business unit, including TETLP, has fully implemented all of the NTSB recommendations. The initiatives that Enbridge has undertaken in response to the Danville, Kentucky incident and the relevant NTSB recommendations have enhanced Enbridge’s programs and efforts. Enbridge believes they will lead to significant advancement of the industry’s management of the hard spot threat. Enbridge is determined to continually improve its safety culture, performance, and to lead industry in safety best practices. Please do not hesitate to contact me if you have any questions or concerns regarding this update.

Addressee Organization Type: P-Private Industry

Communication Date: 2022-12-13

Communication Type: Official Correspondence

Communication Contents: -From Al Monaco, President and Chief Executive Officer, Enbridge Inc.: Enbridge agrees with NTSB recommendation P-22-6. The Enbridge GTM Operator Qualification (OQ) Plan outlines an incident investigation and disqualification process which requires disqualification, remedial training, and requalification when an employee does not follow procedures while performing a covered task, including responding to an emergency shutdown, rupture, or other abnormal operation. See Enbridge GTM OQ Plan, Section 12.1-12.3. If the performance of a covered task caused or contributed to an incident, the investigation will include an assessment of: (1) the appropriateness of the re-qualification interval; (2) the adequacy of the evaluation method; (3) the evaluation; and (4) an assessment of the evaluator’s credentials and ability to conduct evaluations. During this time period, the individual’s qualifications for the covered task(s) in question will be suspended. If disqualified, an individual must successfully complete training related to the task before the individual may be evaluated to again establish qualified status. If the investigation establishes that the incident was not a result of improper performance of the covered task at issue, the individual’s qualification may be reinstated. Since the Danville, Kentucky incident, Enbridge has improved this process to require completion of a qualification reassessment form to document the disqualification process. This GTM OQ Plan enhancement was incorporated on August 17, 2020, and Enbridge believes that its revised OQ investigation and disqualification process satisfies the NTSB’s recommendation to disqualify and require remedial training and requalification when an employee responding to an emergency shutdown, rupture or other abnormal operation does not follow procedures.

Addressee Organization Type: P-Private Industry

Communication Date: 2023-03-30

Communication Type: Official Correspondence

Communication Contents: We note that you revised your operator qualification plan to strengthen your disqualification process, requiring a qualification reassessment form to be completed after every incident. You wrote that the Enbridge Gas Transmission Midstream Operator Qualification Plan requires disqualification, remedial training, and requalification when an employee does not follow procedures when performing a covered task, including responding to an emergency shutdown, rupture, or other abnormal operation. These actions satisfy Safety Recommendation P-22-6, which is classified CLOSED-- ACCEPTABLE ACTION.