a new cp approach on non-isolated and aged pipelines: a case … · 2020. 5. 13. · integrity...
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
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ipe
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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
W h i c h a r e t h e O P T I O N S ?
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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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!
W h i c h a r e t h e O P T I O N S ?
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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
W h i c h a r e t h e O P T I O N S ?
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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
W h i c h a r e t h e O P T I O N S ?
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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
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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
A New CP Approach on Non-Isolated and Aged Pipelines: A Case Study
END OF PRESENTATION