SCC Management

1. SCC Management 16” Camas to Eugene 26” Sumas to Washougal

2. Outline • 16” Camas to Eugene • Background /Issues • Integrity Strategy Execution • Current Status • 26” Sumner to Washougal • Background / Issues • Segment by Segment Strategy • SCC strategy

3. NWP I-5 Corridor 16” Camas - Eugene 16” Camas to Eugene

4. 16” Background / Issues • Oregon City Requalification in 1994 • 22 hydrostatic test failures • Most of these 6 miles downstream at 1000 to 1100 psi • 16” x 0.250” wall; X52; Bitumastic coating; ERW Lonestar steel • MAOP 896 psig • Cracking is SCC (classical high??; near–neutral pH??) • Continued SCC Management (1994-2001) • Through excavations • SCC coupons • Strategy to build & apply ILI • 16” UT Crack Detection (Sept. 2001) • Liquid slug; no fun in a gas pipeline, max elevation 300+ feet • Ensure longer term integrity (where are the subcritical cracks)

5. 16” UT ILI C-Scan

6. 16” Short term Integrity Strategy • API 579/BS7910; Level II and III; Well established • JIC = 257lbs/in; SMYS=52 ksi; SMUTS=66 ksi • Pressure 1.39 MAOP (1245 psi) • Crack size = upper bound value from ILI + 10%wt • Immediate Repairs • Nine of several hundred features un-acceptable • Identified couple of hundred • Depth 25-40%wt: 9 features • 12.5-25%wt: • <12.5%wt: • 2002 digs validated ILI accuracy • Length and Depth range (grinding) • Elastic-Plastic Fracture Mechanics Type • Industry Standards: API 579, BS7910:1999 • Level 2 Assessment • Low bound FAD Equation • Very conservative • Level 3 Assessment • Based on measured stress-strain curve • Based on measured R-curve • Accurate and less conservative

7. 16” Future Integrity & Current Status • Based on 2001 ILI and 2003 Field • Establish growth rate using linear assumption • Excavation data from the field • Growth Rate = 0.03 in/year • Excavation and Re-inspection driven • 22.5 to 35% requires action in 4-6 yrs • NO INCIDENT • Validates Strategy • ILI identify sub critical • Fracture mechanics evaluation • Continued monitoring & repairs 2004+ No Incident since Integrity strategy implemented; Continuous Improvement

8. 26” Snohomish to Washougal • Primarily 26” O.D. , 0.281” wt • DSAW pipe, X-52 • Field applied bitumastic asphalt • Installed in 1956 • Regular Corrosion Inspection • Only Snohomish to Sumner SCC susceptible • One Incident (at MAOP 674 psi – 59% SMYS) • SCC in 2003 • Lake Tapps Segment specific Integrity Strategy

10. 26” Critical Size & Crack Growth Rate • Maximum survived flaw size is a function of (FAD Level II): • length and depth,& Pressure applied (Class Location) • Actual yield, tensile, and toughness properties (upper bound value used) • Crack growth rates (literature & field) • Re-hydro re-inspection was 2 years • Re-inspection was 6 – 9 years Sub critical crack size defines integrity strategy

11. 26” Segments of the System No SCC failure 3 insignificant SCC identified DA model being applied No SCC ever found DA model being applied • 2003 SCC failure • Crack detection completed • DA model being developed • No SCC susceptibility • DA Model being developed SCC susceptible – ILI driven; No SCC – DA to establish susceptibility

12. SCC Integrity Strategy • ILI Data • Soils, Terrain, Topo Model • Coating Disbondment • Corrosion Linearity (MFL) • Pipe Design • Material Properties • CP Data • Susceptibility • DA driven • Extent of susceptibility defines IMP • Life Cycle Modeling • Fracture mechanics driven • Crack growth rate driven • Mitigation strategy (data and analyses driven) • ILI or Hydro • Repair, grind out, or replace SCC Susceptibility Model Sampling Model Confirmatory Excavations Cyclic Pressure History Existing Defect Size Distribution Life Cycle Modeling Applicable SCC Rate Studies Future Integrity Model Integrity Actions Ongoing SCC Monitoring SYSTEMATIC, DATA & MECHANISM-DRIVEN STRATEGY CRITICAL