Download - 2008-11-Spetsneftegaz
“NPO SPETSNEFTEGAZ”
Efficient Ways of Increasing In-Line Inspection Reliability
Statistics of In-Line Inspection of GAZPROM pipelines during the last 5 years
• Total 77,900 km gas pipelines were
inspected in “GAZPROM” JSC
• More than 1.5 million pipeline defects
were detected
• 6947 stress corrosion cracking zones
were located and sized
Quantitative Statistics on Types of Detected Defects
Cracks Girth weld anomalyDents Anomaly and mill defectPitting General CorrosionCircumferential groove Axial groovePinhole
Main Disadvantages of MFL method
• High magnetization level
• Estimation of defect severity level strongly
depends on pipeline defect identification
High magnetization level
High magnetization level
High magnetization level
• Active electronic bypass (speed control) device
V = 0
V = 4 m/s
High magnetization level
• Advantages of ordinary SNG ILI tools
High magnetization level
• Alternative magnetization scheme
Very high friction
Disadvantages of MFL method
• In-line inspection of pipelines with thick walls is
limited due to necessity to magnetize full pipe
wall thickness up to outer pipe wall surface
• All new Russian pipelines including Nord-Stream
pipeline are thick wall pipelines
• Only limited inspection is possible on almost all
offshore pipelines
Comparison of ILI technologies detection of cracks
with superimposed general corrosion
Photo of cracks on corrosion background
Pipeline defects identification statistics
• Dig verification statistics reveals real ILI tool sensitivity
• Latest results of MFL &TFI methods usage:– POD of cracks less than 20% p.w.t. deep is
90%– POI of cracks less than 20% p.w.t. deep is
90%– POI of shallow cracks with superimposed tiny
corrosion is less than 60%
“NPO SPETSNEFTEGAZ”
Advantages of EMAT In-Line Inspection
EMAT in-line inspection
Pipe
Coating
EMA system
Waves
Artificial crack signals
EМАТ
TFI
CrackHole
Length 41 mmDepth 4 mmWidth 0.01 mm
Crack
Hole
EMAT in-line inspection
EМАТ
TFI
EMAT in-line inspection experience
EMAT in-line inspection experience
EMAT in-line inspection experience
EMAT in-line inspection challenge
• Cracks with nearly zero opening– Detection– Identification– Sizing
• Thick pipe wall corrosion damage– Detection– Identification– Sizing