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Dr. Olaf StawickiROSEN Technology and Research Center, Germany
NACE TOL Conference Jakarta Indonesia 27-29 July-2015
COMBINED ILI APPROACH FOR PIPELINES WITH TOP OF LINE CORROSION AND CRA LAYER
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CONTENT
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
ILI Perception of top of line corrosion Overcoming TLC: Corrosion Inhibitor & Corrosion Resistant Alloy (CRA) ILI Technologies: Magnetic Flux Leakage & Eddy Current ILI Technologies: Combined world Inspection Example: Carbon Steel Pipe without CRA Trial Program with CRA Pipe Conclusions
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Top of Line Corrosion
Localized, small-scale corrosion (PINH, PITT) Dissolution of aggressive gases in
droplets support corrosion Can reveal high growth rates, up to several mm/year
ILI PERCEPTION OF TOP OF LINE CORROSION
TExt
Stratified Water Flow
Water Drain
Droplet Condensation TExt TGas
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015 Slide 4
Condensation rate depends on Temperature Temperature equilibrium between pipeline and surrounding TLC typically occurs in the first kilometers of pipelines
ILI PERCEPTION OF TOP OF LINE CORROSION
Corrosion Inhibitor or CRA pipes applied for such high risk areasNACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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OVERCOMING TLC: JET PIG APPROACH
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
Traditional Spray Pig Approach based on Venturi Effect and/or Bypass
Jet Pig Approach utilizes a battery powered motor with pump:a) Pig 1 and 2 include Corrosion Inhibitor (CI) batch. Pig 2 pumps CI out of
the batch and spread it to the top of line.b) Concept works effectively even under low pressure conditions.
c) No bypass or Venturi effect required
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Typical types of CRA Mechanical bonded (lining) Metallurgical bonded (cladding)
Typical CRA materials
Stainless steel 316L Inconel 625, 825
Prior to installment/construction No concerns for integrity Inspection not considered
Since installment/construction Concerns emerged Actual incidents occurred
OVERCOMING TLC: CORROSION RESISTANT ALLOY
Corrosion Resistant Alloy (CRA)Layer Thickness: ca. 3 mmLined or claddedAustenitic: Non-magnetic
Standard Carbon Steel
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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OVERCOMING TLC: CORROSION RESISTANT ALLOY
Expected defects in CRA pipe External defects in carbon steel (CS),
e.g. corrosion Internal defects between carbon steel
and stainless steel Erosion in CRA due to e.g. sand
Pitting in the CRA e.g. caused byseawater ingress or galvanic corrosion
Geometric deformations in CRA (e.g. wrinkles, dents)
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015 Slide 8
ILI TECHNOLOGIES
In offshore pipelinesa) reference outside measurements orb) local repairs
are impossible or at least difficult.
ILI is an inevitable measure for assessing the current state of the asset:
Ultrasonic inspection requires batching for gas pipelines=> cost intensive, environmental concerns
Magnetic Flux Leakage (MFL) and Eddy Current (EC) are robust ILI techniques with reliable data coverage even under harsh conditions
but are BOTH applicable to BOTH the CRA layer and CS carrier?
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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ILI TECHNOLOGIES - MAGNETIC FLUX LEAKAGE
48 RoCombo MFL-A/IEC
Internal and external metal loss can be sized
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015 Slide 10
ILI TECHNOLOGIES - MAGNETIC FLUX LEAKAGE
Without CRA Layer With CRA Layer
FEM simulations for 8: 10 mm CS, 3 mm CRA Layer
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
Speed effects are worsening magnetization and detection capabilities
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ILI TECHNOLOGIES - MAGNETIC FLUX LEAKAGE
MFL susceptible to ferromagnetic material only, but not to austenitic steel CRA layer results in degradation in magnetization Austenitic CRA layer roughly represents air gap
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
FEM simulations for 8: External defect in CS, 24 mm x 24 mm, depth 65%
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ILI TECHNOLOGIES - EDDY CURRENT
Sensor over metal lossSensor over full pipe wall
Pipe wall
Internal metal loss can be sized from response signal
48 RoCombo MFL-A/IEC
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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ILI TECHNOLOGIES - EDDY CURRENT
Radius Measurement =
Lift-Off Sensor+
Electronic Angle Sensor
4
6
8
10
12
0 0.04 0.08 0.12 0.16 0.2 0.24 0.28 0.32 0.36 0.4 0.44 0.48
Time (sec)
C
o
m
p
e
n
s
a
t
e
d
S
i
g
n
a
l
Absolute sensor position is known in every moment: compensate scaling (negative radius impact), size general metal loss (positive radius anomaly) monitor for ID anomalies
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015 Slide 14
ILI TECHNOLOGIES COMBINED WORLD
General Material Response MFL is suitable for ferromagnetic materials only (CS) MFL is not suitable for non-magnetic steels (316L, alloys 625 & 825)
EC is suitable for ferromagnetic materials (CS) and non-magnetic, but conductive materials (316L, alloys 625 & 825)
For Carbon Steel Pipe without CRA:MFL and EC complement each other for internal metal loss (TOLC) Direct assessment of defect shape via EC Indirect improvement of MFL depth sizing based on EC shapeFor Carbon Steel Pipe with CRA:MFL and EC complement each other MFL for detection of metal loss in CS carrier EC for monitoring inner surface of CRA layer
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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CARBON STEEL PIPE WITHOUT CRA
1m Offshore Pipeline with Internal Pinholes AUT 1 mm sampling; significant depth values in % of wall thickness
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015 Slide 16
CARBON STEEL PIPE WITHOUT CRA
MFL picks up smallest indications, but blooming dominatesData interpretation is ambiguous examples a,b,c
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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CARBON STEEL PIPE WITHOUT CRA
EC data reflect even tiniest pinholesAccurate shape from EC, subsequent more accurate depth from MFL
EC
MFL
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015 Slide 18
CARBON STEEL PIPE WITHOUT CRA
MFL Stand Alone Result
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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CARBON STEEL PIPE WITHOUT CRA
Combined result, higher accuracy, significantly reduced oversizing
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015 Slide 20
LARGE SCALE TRIAL PROGRAM WITH CRA PIPE
8 Pump testsMFL, EC and UT ILI tools
Ext. Feature CS
Ext. FeatureCS &CRA
Int. Feature CRA
Int. FeatureCRA &CS
Test spool 8, 10 mm WT CS, 3.9 mm WT CRA (cladded, Alloy 825)with artificial defects of class Pitting
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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LARGE SCALE TRIAL PROGRAM WITH CRA PIPE
Defect #1: ext. in CS, 6.5 mm depth
Defect #2: ext. in CS & CRA, 13.0 mm depth
MFL (NIC) IEC
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015 Slide 22
LARGE SCALE TRIAL PROGRAM WITH CRA PIPE
Defect #3: int. in CRA, 3.0 mm depth
Defect #4: int. in CS & CRA, 10.9 mm depth
MFL (NIC) IEC
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
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CONCLUSIONS
Systematic and even single metal loss over-sizing is of specific concern for offshore and specifically TOLC affected pipelines.
Oversizing is reduced significantly by employing different but complementing ILI technologies: Eddy Current & Magnetic Flux Leakage.
TOLC monitoring is complemented with the accurate assessment of severe general and embedded corrosion, with the high definition caliper component.
Jet Principle Pig for effective CI distribution is considered Combined MFL/EC approach allows to inspect CRA and CS in
lined/cladded pipes
Liquid coupling (cost intensive batching) as for UT inspection not required
NACE TOL Conference Jakarta Indonesia 27-29th July 2015 Dr. O. Stawicki ROSEN Group 2015
www.rosen-group.com
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