EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
Transcript of EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
1/52
---
A 30.01.2012 ISSUED FOR INFORMATION O.Y O.Y E.D
Rev.
No. Date Description
Prepared Checked Contr. By Approved ------------
ORIGINATOR Published by
EDOPEC ENERJ PETROL MHENDSLK SANAY VE TCARET LMTEDRKET
Contractor
Document Title
Corrosion Management and Cathodic ProtectionOffice :
PalmiyeMah. Adnanmenderes Bulv. Oktay Sitesi
No: 9/8 PK = 33100 Yeniehir /Mersin TURKEYP:+90 324 3260595
F:+90 324 3260596
Ankara Office :UUR MUMCU CAD(krolucad) ERDL APT87/13 Gop-ankaya -Ankara-TURKYEP: +90 312 447 17 18 / 20
F:+90 312 447 17 21
stanbulOffice:BurhanyeMahalles amlca Caddesihlamurvi llalar no 28 / 6^RD3K Villa ^Beylerbeyi skdar stanbul / TURKEYP : +90 216 4220414 PBX
F: +90 216 4220415
Document No.
EDO PPP COE COR INT XXX 013 051 052 Rev ACo. Org.
Cod
Doc
Type
Disc.
Code
Unit
Code
Prj.
type
Prj.
NO
Prj.
Year
Pro.Doc.
Seq.No
DCC Seq.NoPage Scale
53
http://www.edopec.com/mailto:[email protected]:[email protected]:[email protected]://www.edopec.com/ -
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
2/52
Head Office : Palmiye Mah. Adnan menderes Bulv. Oktay Sitesi No: 9/8 PK = 33100 Yeniehir /MersinTURKEYP:+90 324 3260595 F:+90 324 3260596
Ankara Office : UUR MUMCU CAD(Krolu cad) ERDL APT 87/13 Gop-ankaya -Ankara-TURKYEP: +90 312 447 17 18 / 20 F:+90 312 447 17 21
stanbul Office: BURHANIYE MAHALLESI AMLICA CADDES HLAMUR VLLALARI NO 28 / 6 ^^RD 3K VLLA ^^Beylerbeyi skdar STANBUL / TURKEY P : +90 216 4220414 PBX F: +90 216 4220415
EDOPEC ENERJ PETROL MHENDSLK SANAY VE TCARET LMTEDRKET
www.edopec.com. [email protected]
Corrosion Management andCathodic Protection
http://www.edopec.com/mailto:[email protected]:[email protected]://www.edopec.com/ -
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
3/52
Edopec Corrosion divisions
is organized with a vision of providing engineering services and manufacturing
for Authorities and Clients located in Turkey , Iran , irak Syria and Middle-
east.Libya ,
Our focus is on complete Cathodic Protection services including all of the
Consultation, Survey, Design, production and installation related work for On-shore & Off-shore facilities, Off-shore & Marine inspection and Industrial
Automation for:
Oil and Gas Industries (offshore & onshore)
Petrochemical industry
Energy
Cement industry
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
4/52
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
5/52
Project
Manger
Procurementbody
QC and Testbody
Logisticcoordinator
TechnicalSupport
Erection Group
Documentation
GroupElectrical
Group
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
6/52
PROJECT ACTVTES
ACTIVITY DETAILS
ENGINEERING & DESIGN
Direct Assessments Services;
Soil Resistivity Survey, CAT (Current Attenuation Test) Survey, DCVG (Direct Current Voltage/Gradient) Survey, Current
Requirement/Drainage Survey, CIPS (Close Interval Potential) Survey, Stray Current Interference Survey, Polarization and On/Off Potential
Survey, Coating Resistance Survey, Anode bed Resistance Survey, Buried Structures Natural Potential Survey, Overhead line Effect on
Buried Structures Survey, (SRB) Sulphur Reduced Bacteria Survey, pH Survey, Carbonate And Sulphate Ions Survey, Grounding System
Resistance Survey, Internal Cathodic Protection and microbial corrosion monitoring and inspections.
Engineering Design;
Basic & Detailed Design of Cathodic Protection systems for Pipelines, Tank Forms, Petro-Chemical Plates, Power Plants, vessels, harbors,
Jetties, offshore and marine structures by both means of SACP and ICCP system (where applicable) Design of SCADA based ICCP
systems, Design of Stray Current and AC mitigation Systems.
Materials/Equipment Design;
Design and development of various types of CP Trans/rectifier Units, Design and development of Special Power Supply units, Design and
development of RRU systems ( Remote Rectifier Units), Design and development of RMU systems ( Remote Monitoring Units), Design anddevelopment CP Remote Monitoring and Control systems. Design and development of GPS synchronized On/Off control of T/R units,
Design and Development of Current Control boxes, Sacrificial anode design.
PROJECT MANAGEMENT Project management of SCADA based ICCP systems, Project management of ICCP and SACP systems, Project management of Local
Cathodic Protection of Oil and Gas and Energy Facilities.
COMMISSIONING
& START UP
Deepwell and shallow groundbed installations, ICCP systems for Pipelines and Storage Tanks, ICCP systems for Congested area and
Tank Farms, SACP installation for interior surfaces of storage tanks, SCADA based Cathodic Protection systems, CP Remote monitoring and
Control systems, Galvanic CP and ICCP systems for Pipelines, Storage Tanks and Tank Farms, CP systems for Marine Structures and
Offshore Pipelines, Galvanic CP and ICCP systems for Ships, Vessel, Jetties and Piers, Internal Galvanic CP and ICCP systems for Water
Tanks and Boilers, Galvanic CP and ICCP systems for Reinforcing steel in Concrete Structures, SCADA communication systems (Wireless,
Satellite, GSM, Fiber Optics) , Installation and replace of permanent reference electrodes under the tank bottom plate for further potential
monitoring proposes via. horizontal drilling technology.
EQUIPMENT MANUFACTURE Fabrication and production of TR units ICCP anodes, Sacrificial anodes, current control and junction boxes, Coupons and reference
electrodes.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
7/52
PRODUCTION and SUPPLY
Item Product
1 Transformer Rectifier Units
2 Test, Junction, Bond Boxes
3 Current Control and Compensation Boxes
4 Reference electrodes and coupons
5 Cables and connections
6 Remote Monitoring System& Software
7 MMO coated Ti anodes
8 Silicon Iron Chromium Anodes
9 Magnesium anodes
10 Zn Anodes
11 Al Anodes
12 Backfill Materials
13 Miscellaneous
14 Cathodic Protection Software
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
8/52
CATHODIC PROTECTION SYSTEM
SCADA SOFTWARE
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
9/52
CATHODIC PROTECTION SYSTEM
SCADA SOFTWARE
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
10/52
CATHODIC PROTECTION RECTIFIER
UNIT
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
11/52
PRODUCTION and SUPPLY
MAJOR CP SERVICES OFEDOPEC
SITE SURVEYS & INSPECTIONS
SERVICES
ENGINEERING DESIGN, PLANNINGAND R&D SERVICES
INSTALLATION AND COMISSIONING
SERVICES
BACK-UP SERVICES
TRAINING
SITE SURVEYS & INSPECTIONSSERVICESSite surveys are undertaken to evaluate
the corrosion behaviour of different
environments, Cathodic Protectionmonitoring, underwater inspection of
structures, anodes, and coatings ,Earthing and lightning activities by
means of soil, water, location, stray
current and so on testing.
EDOPEC , undertakes the followingsurveys and inspections
Soil Resistivity Survey
CAT (Current Attenuation Test) SurveyDCVG (Direct Current Voltage/Gradient) SurveyCurrent Requirement/Drainage SurveyCIPS (Close Interval Potential) SurveyStray Current Interference SurveyPolarization and On/Off Potential Survey
Coating Resistance SurveyAnode bed Resistance Survey
Buried Structures Natural Potential Survey
Overhead line Effect on Buried Structures Survey(SRB) Sulphur Reduced Bacteria SurveypH Survey
Carbonate And Sulphate Ions SurveyGrounding System Resistance Survey
Contact Voltage (Touch and Step Voltages) SurveyLightning Protection Installation SurveyLightning Protection Level SurveyInternal Cathodic Protection and microbial corrosion monitoringand inspections.
Potential Profile, Current Distribution Survey of Power Plants,
Take-off yards and substations
Sub-sea Platform inspection for maximum deep of 40
meters including repair, wet welding, cutting, anode
inspection ( Cleaning, montage, re-montage,photography)and NDT tests (MPI, FMD, Thicknesstestes)
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
12/52
BACK-UP SERVICES
EDOPEC . maintains close contact with the market so that it cantailor its product offering to the needs of the clients. The
considerable experience has ensured that the Company can
provide complete back-up services from initial design to final
commissioning and maintenance. The aim is to give customers an
efficient, professional service of the highest quality. Comprehensive
range of maintenance and support services provides a further levelof back up, as appropriate.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
13/52
ENGINEERING DESIGN, PLANNING AND R&DSERVICES
The engineering and design phase is one of the key processes during the project execution stage. EDOPEC.
Currently has a core staff of several engineers. All of these have been selected because of their unique alternativeexperience.
We are more than able to provide our clients with the project teams to meet the challenges presented by
mature fields.
Advantages have been successfully involved in almost every advanced engineering project carried out in EDOPEC..Clients have recognised, through the provision of project services, EDOPECs ability to efficiently provide their
requirements.
Basic & Detailed Design of Cathodic Protection systems for Pipelines, Tank Forms, Petro-Chemical Plates, Power Plants,
vessels, harbours, Jetties, offshore and marine structures by both means of Galvanic and ICCP system (where applicable).
Design and development of various types of CP Trans/rectifier UnitsDesign and development of Special Power Supply units
Design and development of RRU systems ( Remote Rectifier Units)
Design and development of RMU systems ( Remote Monitoring Units)
Design and development CP Remote Monitoring and Control Systems
Design and development of GPS synchronized On/Off control of T/R units
Project Design of SCADA based ICCP systems
Project Management of ICCP Galvanic CP systems
Project Design of Local Cathodic Protection of Oil and Gas and Energy Facilities
Design and Planning of CP installation of special ICCP anodes
Design and Planning of Subsea and Offshore Structure CP systemsDesign and Planning of Ships and Vessels ICCP systems
Design and Planning SCADA communication systems
Design and Planning of ICCP Systems for Internal Cathodic Protection
R & D of CP systems of Reinforcing steel in Concrete Structures
R & D on AC interference analysis and mitigation system design
R & D on Projects Safety and Economics
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
14/52
INSTALLATION AND COMISSIONING SERVICES
Edopec Co. have ability to provide installation and commissioning services for the following projects and systems relevant to
Oil & Gas and Energy Industries.
Deepwell and shallow groundbed installations
ICCP systems for Pipelines and Storage Tanks
ICCP systems for Congested area and Tank Farms
Galvanic CP installation for interior surfaces of storage tanks
SCADA based Cathodic Protection systems
CP Remote monitoring and Control systems
Galvanic CP and ICCP systems for Pipelines, Storage Tanks and Tank Farms
CP systems for Marine Structures and Offshore Pipelines
Galvanic CP and ICCP systems for Ships, Vessel, Jetties and Piers
Internal Galvanic CP and ICCP systems for Water Tanks and Boilers
Galvanic CP and ICCP systems for Reinforcing steel in Concrete Structures
Ribbon anode installation for new constructed storage tanks
ICCP system for existing tanks using horizontal drilling technology.
Installation and replace of permanent reference electrodes under the tank bottom plate
for further potential monitoring proposes via. horizontal drilling technology.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
15/52
Fundamentals of Corrosion Corrosion Cell:
Conditions required for corrosion Corrosion Rate Corrosion Types
Commonly Affected Structures Corrosion Control
Materials Selection
Inhibitors/Altering the environment
Coatings
Cathodic Protection Measuring potentials
Criteria
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
16/52
Fundamentals of Corrosion Corrosion Cell:
Conditions required for corrosion Corrosion Rate Corrosion Types
Commonly Affected Structures Corrosion Control
Materials Selection
Inhibitors/Altering the environment
Coatings
Cathodic Protection Measuring potentials
Criteria
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
17/52
Introduction to Corrosion
Corrosion can be defined as the deterioration of metal
due to its interaction with the environment. Corrosion
is a natural phenomenon, which should not surprise
one, but rather should be expected to occur. Metals arehigh energy materials, which exist because heat energy
was added to natural iron ores during the smelting
process. Nature, by environmental contact, constantly
attacks these high energy materials and breaks themdown to the natural elements from which they were
derived.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
18/52
Conditions Required for
Corrosion
Corrosion is an electrochemical process occurring atthe interface between metal and environment. Threeconditions must be present for this to occur.
1. Two areas on a structure or two structures mustdiffer in electrical potential.
2. Those areas, called anodes and cathodes, must beelectrically interconnected.
3. Those areas must be exposed to a commonelectrolyte (soil or water).
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
19/52
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
20/52
Those areas must be exposed to
a common electrolyte
CURRENTFLOW
CURRENT FLOW
IONIZED ELECTROLYTE
WIRE
ANODE(IRON)
CATHODE(COPPER)
CURRENT FLOW
(- TO + IN ELECTROLYTE)
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
21/52
Those areas must be exposed to a
common electrolyte
CURRENTFLOW
CURRENT FLOW
IONIZED ELECTROLYTE
WIRE
ANODE(IRON)CATHODE(COPPER)
CURRENT FLOW
(- TO + IN ELECTROLYTE)
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
22/52
Corrosion Cell Dissimilar Metals
i.e. steel pipe connected to copper ground rod
CURRENTFLOW
CURRENT FLOW
IONIZED ELECTROLYTE
WIRE
ANODE(IRON)
CATHODE(COPPER)
CURRENT FLOW
(- TO + IN ELECTROLYTE)
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
23/52
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
24/52
24
Corrosion Rate
As a result of this process, electric current flows
through the interconnection between cathode
and anode. The cathodic area is protected from
corrosion damage at the expense of the metal,which is consumed at the anode. The amount
of metal lost is directly proportional to the
current flow. Mild steel is lost at approximately20 pounds for each ampere flowing for a year.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
25/52
25
Factors Affecting Corrosion Rate
Potential Difference Between Anode and
Cathode (Galvanic Series)
Circuit resistance Resistivity of the Electrolyte
Chemical Activity
Stray Currents
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
26/52
26
Potential Difference
Interconnecting two dissimilar metals in an
electrolyte will create a corrosion cell. The
strength of this cell increases as the distance
within the galvanic series increases.
G l i S i
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
27/52
27
Galvanic Series
METAL VOLTS (CSE)
Commercially Pure Magnesium -1.75
Magnesium Alloy -1.60
Zinc -1.10
Aluminum Alloy -1.05 Commercially Pure Aluminum -0.80
Mild Steel (clean & shiny) -0.50 to -0.80
Mild Steel (rusted) -0.20 to -0.50
Cast Iron (not graphitized) -0.50
Lead -0.50 Mild Steel in Concrete -0.20
Copper, Brass, Bronze -0.20
High Silicon Cast Iron -0.20
Carbon, Graphite, Coke +0.30
Example: connecting magnesium to copper will produce a corrosion cell with a
potential of about 1.5 volts.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
28/52
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
29/52
29
Resistance of Common Electrolytes
Soils High resistivity water reduces thecorrosion rate, while low resistivity water
increases the corrosion rate.
CLASSIFICATION
ELECTROLYTERESISTIVITY
(ohm-cm)
ANTICIPATEDCORROSIVITY
Low Resistance 0 to 2,000 Severe
Medium 2,000 to 10,000 Moderate
High 10,000 to 30,000 Mild
Very High Above 30,000 Increasingly Less
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
30/52
30
Resistance of Common Electrolytes
Water Approximate resistivity values
Water resistivity Ohms-cm
open sea 20-25
seawater (coastal) 30-40river water 500-10,000
tap water 1,000-10,000
rain water 20,000
distilled water 500,000
pure water 20,000,000
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
31/52
31
Chemical Activity
Passive (less corrosive) Environment
High pH (neutral or basic)
Low Moisture Content Lack of Salts
High Resistivity
Low Temperature Homogenous Environment
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
32/52
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
33/52
Stray current corrosion
Boat1
Boat2
Boat3
Ground
wire
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
34/52
34
Corrosion Type
Uniform or near uniform - Corrosion attacks all
areas of the metal at the same or similar rate.
Localized - Some areas of the metal corrode at
different rates due to heterogeneities in the
metal or environment. This type of attack can
approach pitting.
Pitting - Very highly localized attack resulting insmall pits that may penetrate to perforation.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
35/52
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
36/52
36
Commonly Affected Structures
Buried Piping
Steel Piles
Storage Tanks - Above Ground / Underground
Reinforcing Steel in Concrete
Ships/Boats
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
37/52
37
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
38/52
38
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
39/52
39
Methods to Control Corrosion
Use of Corrosion resistant materials (plastic, stainless
alloys, fiberglass).
Use of the same or similar metals per the galvanic
series. Altering the environment (utilizing homogeneous high
resistivity backfill or inhibitors).
Utilize coatings and linings that electrically insulate thestructure from the electrolyte (paints, plastic films, etc).
Use of Cathodic Protection.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
40/52
40
Fundamentals of Cathodic
Protection
Cathodic Protection (CP) Defined - Minimize
corrosion by utilizing an external source of
electrical current which forces the entire
structure to become a cathode.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
41/52
41
1824: Earliest practical use of cathodic protection
Sir Humphrey Davys work on protecting thecopper sheathing on wooden hulls in the
British Navy by sacrificial zinc or iron anodes is
generally considered to be the earliest
example of practical cathodic protection.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
42/52
42
Galvanic CP
When metals such as magnesium or zinc are
placed in the environment in contact with a
more noble metal such as steel, a current flows
from the more active anode to the noblecathode (corrosion cell).
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
43/52
43
Anodes Used for Galvanic CP
Magnesium Magnesium is often used in soil toprotect small electrically isolated structures, suchas underground storage tanks, and well coated
pipelines. Zinc Zinc is often used in marine
environments. They are commonly found onboats.
Aluminum Aluminum can be used for a varietyof marine applications.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
44/52
44
Keys to obtaining enough cathodic protection
Determine amount of current required
Theoretical calculations based on coating quality
and environmentOr, perform current requirement testing
Calculate output expected from anode and
determine number of anodes required.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
45/52
45
Galvanic CP
Pros of Galvanic CP
Inexpensive
Little Maintenance cost No external Power source
A variety of install methods can be used. For
example, many USTs are shipped with anodesattached.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
46/52
46
Galvanic CP
Cons of Galvanic CP
Typically work best with electrically isolated structures.
No external power source, limited driving potential
(driving potential based on the galvanic series) Limited output makes it ineffective when trying to
protect large uncoated surfaces.
Require a low resistivity electrolyte to function well.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
47/52
47
Impressed Current CP
Utilize an external power source to develop a
high potential difference between the surface to
be protected and an anode.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
48/52
Impressed Current CP
Anode Groundbed
Rectifier
Negative Cable
Positive Cable
AC Power Supply
Pipeline
IMPRESSED CURRENT SYSTEM
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
49/52
49
Impressed Current CP
Pros of Impressed Current CP
Unlimited driving potential.
Capable of protecting large steel structures
when designed properly. Requires less anodes then a galvanic system.
Output can be controlled using a permanent
reference electrode, desirable when theelectrolyte resistivity is known to change.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
50/52
50
Impressed Current CP
Cons of Impressed Current CP
Initial costs can be more expensive.
Requires an external DC power source along
with an AC supply.
System requires routine maintenance and
monitoring.
Anode wires can be susceptible to damage.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
51/52
51
Impressed Current CP Rectifier
A rectifier converts available AC power to low
voltage DC power. Most cathodic protection
rectifiers are provided with a means to vary the
DC output voltage in small increments, or insome cases offer complete control from zero to
100% of rated DC output.
-
8/13/2019 EDO PPP COE COR INT XXX 013 051 52 Rev a Corrosion Management and Cathodic Protection
52/52
CP System Testing
A CP system can be evaluated by obtaining a
reference cell potential. This potential
determines the amount of cathodic polarization
the structure is receiving.Adequate protection is indicated by obtaining a
value more negative then the established criteria.
This criteria is specific to the reference cell usedto obtain potentials.