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

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

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

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 ( ) –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)

16” UT ILI C-Scan

16” Short term Integrity Strategy Identified couple of hundred –Depth 25-40%wt: 9 features – %wt: –<12.5%wt: 2002 digs validated ILI accuracy –Length and Depth range (grinding) API 579/BS7910; Level II and III; Well established J IC = 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 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

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 No Incident since Integrity strategy implemented; Continuous Improvement

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 (north to south) Sumas to Mt Vernon 44 miles Mt Vernon to Snohomish 46 miles Snohomish to Sumner 42 miles Sumner to Ft. Lewis 17 miles Ft. Lewis to Chehalis 46 miles Chehalis to Washougal 73 miles Segment specific Integrity Strategy

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

26” Segments of the System Segment (north to south) Sumas to Mt Vernon 44 miles Mt Vernon to Snohomish 46 miles Snohomish to Sumner 42 miles Sumner to Ft. Lewis 17 miles Ft. Lewis to Chehalis 46 miles Chehalis to Washougal 73 miles 2003 SCC failure Crack detection completed DA model being developed No SCC failure 3 insignificant SCC identified DA model being applied No SCC ever found DA model being applied No SCC susceptibility DA Model being developed SCC susceptible – ILI driven; No SCC – DA to establish susceptibility

SCC Integrity Strategy 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 SYSTEMATIC, DATA & MECHANISM-DRIVEN STRATEGY CRITICAL Life Cycle Modeling Confirmatory Excavations SCC Susceptibility Model Ongoing SCC Monitoring Sampling Model Existing Defect Size Distribution Cyclic Pressure History Future Integrity Model Integrity Actions Applicable SCC Rate Studies ILI Data Soils, Terrain, Topo Model Soils, Terrain, Topo Model Coating Disbondment Coating Disbondment Corrosion Linearity (MFL) Corrosion Linearity (MFL) Pipe Design Pipe Design Material Properties Material Properties CP Data CP Data