09 - Olaf Stawicki (ROSEN) - Combined ILI Approach for Pipelines With Top of Line Corrosion and CRA Layer

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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

Slide 2

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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Slide 3

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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Slide 5

OVERCOMING TLC: JET PIG APPROACH


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

Slide 6

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


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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)


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?


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Slide 9

ILI TECHNOLOGIES - MAGNETIC FLUX LEAKAGE

48 RoCombo MFL-A/IEC

Internal and external metal loss can be sized



Without CRA Layer With CRA Layer

FEM simulations for 8: 10 mm CS, 3 mm CRA Layer


Speed effects are worsening magnetization and detection capabilities

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Slide 11


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


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


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Slide 13

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


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


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Slide 15

CARBON STEEL PIPE WITHOUT CRA

1m Offshore Pipeline with Internal Pinholes AUT 1 mm sampling; significant depth values in % of wall thickness



MFL picks up smallest indications, but blooming dominatesData interpretation is ambiguous examples a,b,c


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Slide 17


EC data reflect even tiniest pinholesAccurate shape from EC, subsequent more accurate depth from MFL

EC

MFL



MFL Stand Alone Result


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Slide 19


Combined result, higher accuracy, significantly reduced oversizing


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


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Slide 21


Defect #1: ext. in CS, 6.5 mm depth

Defect #2: ext. in CS & CRA, 13.0 mm depth

MFL (NIC) IEC



Defect #3: int. in CRA, 3.0 mm depth

Defect #4: int. in CS & CRA, 10.9 mm depth

MFL (NIC) IEC


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Slide 23

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


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THANK YOU FOR JOINING THIS PRESENTATION.

09 - Olaf Stawicki (ROSEN) - Combined ILI Approach for Pipelines With Top of Line Corrosion and CRA Layer

Documents

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droplets support corrosion

smallscale corrosion

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cra pipe external defects