Wall Thickness Data Collection Southern Nevada Division Southern

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 � 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

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

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

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

Southwest Gas Challenges � 1979 Acquired gas system from Tucson Gas and Electric � 1984 Acquired gas system from Arizona Public Service

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

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)

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

Southern Nevada Division Explorer Project Las Vegas

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

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

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

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

Work site congestion

Manual Tether

Planning/Lessons Learned � Pre excavate pits, larger than standard bellholes � 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

T N E G T N I A P ND E P

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

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

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

� Questions on Explorer project?

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

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

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

Dig and Inspects in So. AZ

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 $50 K �Allowed reclassification 2. 5 miles of pipe to highpressure distribution �Lowered comparative risk

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

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

� Questions? ? ? k n a Th You