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Direct Assessment. Philip Sher Connecticut Department of Public Utility Control Gas Pipeline Safety Unit. Representing NAPSR National Association of Pipeline Safety Representatives November 4, 2003. NAPSR. NAPSR = National Association of Pipeline Safety Representatives
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Direct Assessment Philip SherConnecticut Department of Public Utility Control Gas Pipeline Safety Unit Representing NAPSR National Association of Pipeline Safety Representatives November 4, 2003
NAPSR • NAPSR = National Association of Pipeline Safety Representatives • non-profit organization • state pipeline safety directors, managers, inspectors and technical personnel • to support, encourage, develop and enhance pipeline safety regulation • Founded on December 2, 1982
Integrity Management Program Pipeline IMP = “a plan or system” “to handle or direct with a degree of skill” the “soundness” of a pipeline system
We Need Integrity Management Bellingham, WA Carlsbad, NM Edison, NJ
ANSI Gas Piping Technology Committee & ANSI B31.8SIntegrity Management Process.
Integrity Assessment Methods • Smart pig • Pressure test • Direct assessment • Other (new technology)
Smart Pigs • 1st smart pigs – mid 1960’s, primarily for the detection of wall thinning. Now other types of defects - cracks, coating disbondment, dents and gouges - are detectable • Smart pig digs have served to calibrate and validate smart pig results
Smart Pigs • Smart pigs need • launchers & receivers • long radius bends • full opening valves • constant pipe diameter • Smart pigs may require interruption • 25-30% of transmission pipelines are piggable
Pressure Testing • Require taking pipeline out of service • Water removal can be difficult • Water can promote internal corrosion • Pressure testing can grow subcritical flaws into critical flaws • Pressure test provides limited information and limited evaluation of future performance
Direct Assessment • ECDA = External Corrosion Direct Assessment • ICDA = Internal Corrosion Direct Assessment • SCCDA= Stress Corrosion Cracking Direct Assessment
ECDA 4 Step Process • Step 1 - Pre Assessment • Step 2 - Indirect Examination • Step 3 - Direct Examination • Step 4 - Post Assessment
Direct Assessment • Absolute need for DA • MUST be perfected • Must define parameters where it works • Must define parameters to evaluate it in use • Must develop body of knowledge and talent to utilize DA
Tools of ECDA • Cathodic Protection Readings (CP)
Tools of ECDA • Close Interval Survey (CIS)
Tools of ECDA • Direct Current Voltage Gradient (DCVG)
Tools of ECDA • C-Scan (The C-Scan mode or pulse-echo provides a planar view image at a specific depth. Illustrations of delaminations and void formation can be generated.)
Tools of ECDA • Current Mapper
Direct Assessment • Some DA tools are old and there is considerable experience • Some DA tools are new with little experience • The DA process is new incorporating old and new tools, old and new techniques, and significant new data integration and documentation
Direct Assessment • Just as smart pig needed calibration and verification, DA will also need to be proven for the many conditions that may exist. • DA must be repeatable • DA must have a high level of confidence • Operator must demonstrate compliance • Regulator must confirm compliance
Reassessment Period • Original proposed reassessment period • Final reassessment period?