A New CP Approach on Non-Isolated and Aged Pipelines: A

Institute of Corrosion’s Corrosion Engineering Division (CED)Working Day and Symposium on “Corrosion Control in Transport and Infrastructure”April 29th 2020

A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study

Pablo Merino – CP Technical AuthorityICORR Level 3 BS EN ISO 15257

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An aged pipeline with anoversaturated CP SystemNOT achieving full extendprotection criteria

Can we change the protection criteria to a less restrictive one? Is this allowed?

If yes, how can we assess that we have achieved a suitable CP protection?

Int

ro

du

ct

ion

Practical approach to a pre-existing condition

What can we do?

Keep upgradingthe existing CP System?

Isolate or rehabilitate coating, etc.

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Configuration • 2X Ø10” operational pipelines running in parallel within the same easement

• Other 3X 10” mothballed pipelines running in parallel.• 2X abandoned water pipelines joins the scheme within

the last 12kms

Length 33,7 Kms

Coating Coal Tar Enamel

Construction 1957

Product Aviation Fuel

Isolation Isolating Joints (IJ) at each endNo IJs for the abandoned water pipes

Th

e P

ipe

lin

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Start: 5X parallel Pipelines

2X abandoned pipes joins the scheme

Last 12 Kms

AGI Isolating Joints

AGI Isolating Joints

No Isolating Joints

Th

e P

ipe

lin

e

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Type Impress current cathodic protection (ICCP)

Configuration • A total of 20 CP Stations (CPS) are installed along the pipelines easement

• All 7X pipelines are electrically bonded• Not all bonding locations are known (buried direct bonds)• Most of the CPSs drain points are used as bonded

facilities

d.c. Current Output 560 Amps

Current Density 7-10 mA/m2

T h e C P S y s t e m

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CPSs spaced between 1 to 8 kms

T h e C P S y s t e m

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Last CP interim/annual inspections shows several locations NOT achieving BS EN12954 criteria (confirmed also over d.c. coupons)

Last On-line Inspection (CIPS) confirmed several pipeline sections with potentials less negative than -850mV

In-line inspection (ILI) results shows several corrosion features (*)

Coating condition is considered to be DEFICIENT. One of the mothballed pipelines is considered to be almost bare

How can we address the problem?

(*) Not necessarily related to ineffective CP condition

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❑ Electrical isolation

❑ Upgrade of the existing CP system

❑ Coating rehabilitation

❑ Change CP criteria for a less restrictive one

W h i c h a r e t h e O P T I O N S ?

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❑ Electrical isolation

Isolate the 2X operational pipelines from the rest of pipelines and re-balance the existing CP system

• Not possible to remove all bonds• Several unknown directs bonds exist along the

pipelines route which are not controlled• Not all bonds are able to be identified by ILI

Feasible? NO


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❑ Coating rehabilitation

Repair/rehabilitate the pipelines coating on those sections/locations where CP criteria is not achieved

Feasible? NO

• All 7X pipelines shall be considered for re-coating• Long term solution• Costs involved are considered as unaffordable!


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❑ Upgrade of the existing CP system

Install New CP Stations to cover all sections/ locations not achieving criteria

Feasible? NO

• The pipeline is already oversaturated with CPSs• Not achieving locations are close to existing CP Stations (Duplicate CPS?)• Increase current output = Increase stray currents to other 3rd parties


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❑ Change CP criteria for a less restrictive one

Re-classify the pipelines scheme as “Complex Structure” under standard BS EN 14505

Feasible? POSSIBLE

• Confirm if BS EN 14505 criteria is suitable for the pipeline integrity

• Scheme shall comply with BS EN 14505 classification


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“It is applicable to structures, which are to be cathodically protected, but cannot be electrically isolated, whether for technical or safety reasons, fromforeign metallic structures situated in the same electrolyte as the structure to be protected. Such a structure is referred to as a “complex structure”

“For complex structures, the cathodic protection criteria defined in BS EN 12954 should be used where possible. Indeed, the characteristics of complex structures and the special influential factors (see Clause 5) which can occurmeans that it is not always possible on every part of the complex structure to determine by measurement whether these criteria of cathodic protection are met. In this case alternative methods of verification may be selected to ensure an adequate reduction of the corrosion rate”

Does the pipeline scheme meet the

Complex Structure Description?

Wh

at d

oe

s B

S EN

14

50

5 s

ay?

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This is Unknow!!!

What is missing?

Confirm that the reduction of the

corrosion rate is enough to comply with the pipeline remaining

thickness Do

es

BS

EN 1

45

05

su

its

the

p

ipe

line

Inte

grit

y

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STOP upgrading the existing CP system to comply with BS EN 12954 criteria

Confirm which BS EN 14505 “alternative methods of verification” suits thepipeline integrity

FINALLY: Re-balance the existing CP system based on the ECMS and theadopted BS EN 14505 alternative method of verification (CP currentoptimization)

Re-classify the pipeline scheme as “Complex Structure” as per BS EN 14505

Implement an External Corrosion Monitoring System (ECMS) to verify that thereduction of the corrosion rate suits the pipeline integrityT

he

Ne

w S

tr

at

eg

y

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• “On-line" method of monitoring the rate of corrosion and the extent of total metal loss for any metallic equipment or structure.

• Measures the effects of both the electrochemical and the mechanical components of corrosion.

• An ER system consists of an instrument connected to a probe. The instrument may be permanently installed to provide continuous information, or may be portable to gather periodic data from a number of locations.

• The probe is equipped with a sensing element having a composition similar to that of the process equipment of interest.

External Corrosion Monitoring System (ECMS)Electrical Resistance (ER) Technique

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Selection of the most

suitable ER probe system

External Corrosion Monitoring System (ECMS)Electrical Resistance (ER) Technique

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I m p l e m e n t a t i o n

What? Confirm if under a less restrictive CP criteria the corrosion rate isacceptable for the pipeline integrity

What’s the

plan?

Where? Select those more suitable/representative locations along the pipelinewhere BS EN 12954 criteria is not met (both pipeline & permanent coupon). ILIhistoric corrosion feature location is a PLUS

How? Implement a combined CP/ECMS monitoring system = ER probe +Permanent ref cell/d.c. coupon

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I m p l e m e n t a t i o n


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A n d t h e O u t c o m e s a r e …

And if the corrosion rate is not

acceptable?

What comes next?

Institute of Corrosion’s Corrosion Engineering Division (CED)Working Day and Symposium on “Corrosion Control in Transport and Infrastructure”April 29th 2020


END OF PRESENTATION

Documents

A New CP Approach on Non-Isolated and Aged Pipelines: A