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Wall Thickness Data Collection -Southern Nevada Division -Southern Arizona Division

Wall Thickness Data Collection -Southern Nevada Division -Southern Arizona Division. Presented by Doug Gapp Pipeline Safety Planning Dept Southwest Gas Corporation August 19, 2014 Western Region Gas Conference. Timeline of Items Prompting Wall Thickness Data Collection Program.

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Wall Thickness Data Collection -Southern Nevada Division -Southern Arizona Division

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  1. Wall Thickness Data Collection-Southern Nevada Division-Southern Arizona Division Presented by Doug Gapp Pipeline Safety Planning Dept Southwest Gas Corporation August 19, 2014 Western Region Gas Conference

  2. Timeline of Items Prompting Wall Thickness Data Collection Program • San Bruno Incident, September 9, 2010 • Pipeline Hazardous Materials Safety Administration (PHMSA) Advisory Bulletin ADB 11-01, Jan 10, 2011 • Evaluate risk – physical and operational characteristics • California Independent Review Panel San Bruno (Recommendation 5.6.4.2), June 24, 2011 • Program to collect…construction and operating data • PHMSA 2011 Advanced Notice of Proposed Rulemaking (Section D), August 25, 2011 • Requirements for collecting, validating, integrating and reporting pipeline data

  3. Timeline of Items Prompting Wall Thickness Data Collection Program • National Transportation Safety Board (NTSB), August 30, 2011 • San Bruno 29 Recommendations • Recommendations specific to Integrity Management Program (IMP) • Completeness/Accuracy Integrity Management Program Data • Federal legislation, January 3, 2012 • Confirm material strength • Pipelines operating in high-consequence areas (HCAs) • Greater than 30 % specified minimum yield strength (SMYS) • California Public Utilities Commission 17 Hazards Report (Item 4), March 14, 2012 • Verifiable and traceable records

  4. Timeline of Items Prompting Wall Thickness Data Collection Program • PHMSA • Integrity Verification Process • Likely will require action on transmission pipe operating in HCAs and Class 3 and 4 locations

  5. Common Theme • Focus of NTSB, federal legislators, regulatory agencies • Transmission pipelines • HCAs • Data – Know your pipelines so you can properly evaluate risk

  6. Southwest GasChallenges • 1979 Acquired gas system from Tucson Gas and Electric • 1984 Acquired gas system from Arizona Public Service

  7. SWG Proactive Approach • November 2012 proposed field data collection initiative-wall thickness pilot • Goal: improve knowledge and records of company pipeline characteristics • Specifically: • Collect wall thickness data where not documented • Accurately classify pipeline • Appropriate integrity management application • Transmission Integrity Management Program (TRIMP) • Distribution Integrity Management Program (DIMP) • pipe that meets transmission classification by actual properties, not lack of records

  8. Approaches for obtaining wall thickness data • Conventional In-line Inspection (ILI) • Other ILI tools • Pipetel Explorer – Southern Nevada Division (SND) • Dig and inspects (D&Is) • Southern Arizona Division (SAD)

  9. Explorer Inspection Tool • Available for pipe sizes 6” to 36” • Either live or de-gassed pipeline • Wireless/battery operated • ~ 3300 foot range • Camera (front and back) • Remote Field Eddy Current Sensor (RFEC) • Magnetic Flux Leakage (MFL) • Maneuver through standard fittings

  10. Southern Nevada Division Explorer Project Las Vegas

  11. Objective • Successful launch and recover robotic tool (tetherless) • Into a non-live natural gas pipeline • Obtain wall thickness (WT) data • Identify potential metal loss • First SWG commercial application

  12. Southern Nevada Division-Commercial Application • Crossing that prohibited conventional inline inspection tools from passing • Pipeline diameter – 6-inch • Maximum operating pressure (MOP) – 125 psig • 5522 feet unconfirmed wall thickness (WT) • Conservative assumption of 0.083 inches WT • 21 feet 0.156 inches WT • Specified Minimum Yield Strength (SMYS) unknown • Conservative assumption of 24,000 psi • 20.78% SMYS at MOP • Vintages • 1964, 1968, and 1972

  13. ILI Overview • Originally planned for 3 bellholes, ended up with 4 • Tool run twice for each distance • Wall thickness data • Metal loss data

  14. Challenges • Urban location traffic & noise • Night work • Crossing over storm drain • Question: What if it gets stuck? • Answer: Put a leash on the pig

  15. Work site congestion

  16. Manual Tether

  17. Planning/Lessons Learned • Pre excavate pits, larger than standard bell-holes • Horizontal launch • Opted for out of service • Night work due to heat of summer • Reduce project complexity • Heat impacted equipment (no flow to cool) • Improvised air conditioning pipeline

  18. PATENT PENDING

  19. What did we find? • Anomalies • No Immediate or Scheduled repair required • No metal loss locations • 7 suspected dents • 3 suspected dents or material deposits • Wall Thickness data • Majority of pipe is 0.156 inches (11.1% SMYS) • some 0.188 inches WT (9.2% SMYS) • Not the 0.083 inches WT

  20. What’s next? • Validate data – field work • Two locations for inspection • Dent • Lowest WT reading • Updated WT attribute data • Final follow-up with vendor

  21. Explorer Tool in So. NV-Results • Experience with Explorer tool • Once confirmatory digs completed able to correctly classify pipe • Avoided replacement • Explorer cost between $200K-$300K per mile • Compared to $2+ million/mile to replace

  22. Questions on Explorer project?

  23. Southern Arizona Division Dig and Inspect (D&I) Project Yuma

  24. Southern Arizona Division Dig and Inspects -Yuma • Pipeline Diameter – 6-inch • Maximum Operating pressure – 150 psig • 1.3 miles Unconfirmed wall thickness (WT) • Conservative assumption of 0.083 inches • 1.2 miles confirmed WT upstream classified as transmission • Specified Minimum Yield Strength (SMYS) unknown • Conservative assumption of 24,000 psi • 24.9% SMYS • 7 HCAs • Vintages • 1954, 1955

  25. Dig and Inspect Overview • 35 D&I Bellholes • Wall thickness data

  26. Dig and Inspects in So. AZ

  27. Dig and Inspects in So. AZ-Results • 1954 vintage changed to 0.250 wall – 8.3% SMYS • 1955 vintage changed to 0.188 wall – 11.0% SMYS • Cost Comparison • Actual cost was approximately $50K • Allowed reclassification 2.5 miles of pipe to high-pressure distribution • Lowered comparative risk

  28. What next? • Southern Arizona Division D&I: • Yuma-Wellton • Approximately 93,000 feet of 4-inch pipe unknown WT • 2 HCAs • Central Arizona Division Explorer ILI: • Litchfield Ave • Approximately 2500 feet of 6-inch pipe unknown WT • Almost entirely in an HCA

  29. Summary • Pipe with: • Unknown wall thickness? • Operating at high % SMYS? • Actual wall thickness likely higher? • Unpiggable? • Determining actual wall thickness: • Lowers relative risk in HCAs • Accurately classify pipe • Appropriate integrity management application

  30. Questions??? Thank You

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