CATHODIC PROTECTION FUNDAMENTALS
CATHODIC PROTECTION DIVISION
PREPARED BY : ABINASH PADHY NDTCCS
HISTORY OF NDTCCS IN CATHODIC PROTECTION
• NDT Corrosion Control Services (NDTCCS) is a fully owned Saudi Company operating since 1975. NDT & CCS is one of the subsidiary company of well known Abdullah Al-Shuwayer group. Recently major share of NDT CCS has been acquired by Investcorp Bank, a leading financial GCC institution as part of strategic partnership between Abdullah Al-Shuwayer group and Investcorp
• NDTCCS offers Cathodic Protection & NDT Services (Conventional & Advanced).
• Our Cathodic Protection solutions can prevent corrosion in new structures and mitigate corrosion in existing structures for pipelines, refineries, above and underground storage tanks for every industrial market including offshore and marine, which includes Feasibility studies, site surveys, system design,intereference control systems, installation supervision, system commissioning and maintenance. We also supply wide range of CP materials such as Transformer rectifiers, ICCP Anodes & SACP anodes, Junction boxes, remote monitoring systems etc.
CATHODIC PROTECTION SERVICES
CATHOSIC PROTECTION PRE-DESIGN SURVEY
CATHODIC PROTECTION DESIGN ENGINEERING
CATHODIC PROTECTION INSTALLATION FOR
ONSHORE & OFFSHORE
CATHODIC PROTECTION SYSTEM MONITORING AND MAINTENANCE
CATHODIC PROTECTION MATERIAL SUPPLY
CATHODIC PROTECTION SURVEYS
WHY CATHODIC PROTECTION
Corrosion costs money.
The only successful and cheapest way of saving deterioration of metals from corrosion.
No coating is 100% perfect so cathodic protection used in conjunction with coatings to prevent metals from corrosion.
DIAGRAMS DEPICTING CORROSION
WHAT IS CATHODIC PROTECTION
• Cathodic protection is a method for reducing the corrosion rate that can be applied to buried and submerged metallic structures
• Making the structure cathode of a macroscopic corrosion cell by impressing current onto the structure from an external electrode called
Anode.
HOW DOES IT WORK?
• Cathodic protection current is impressed from an external cathodic protection anode through the electrolyte to the metal and reduces the potential difference between anodic and cathodic sites.
TYPES OF CATHODIC PROTECTION SYSTEMS
CATHODIC PROTECTION
ICCPSACP
SACRIFICIAL ANODE CATHODIC PROTECTION SYSTEM
Test Station
Structure
Sacrificial Anode
Flow of Current through Electrolyte
IMPRESS CURRENT CATHODIC PROTECTION SYSTEM
CURRENT DISTRIBUTION
TRANSFORMER RECTIFIER
• AC inputVoltage, Single/ three phase,
Frequency
• DC maximum output Amp, Volt
• Air Cooled: with sun-shadeOil Cooled: with thermometer
• Location: according to area classification • Explosion proof (hazardous area)• Non-explosion proof (non-
hazardous area
IMPRESS CURRENT ANODES
COMMON ICCP ANODES
MMO Coating
Solid Titanium Core
Titanium Substrate with a Copper Core
Titanium Tubular
Titanium Substrate Mesh
Titanium Substrate Ribbon
GRAPHITE ANODES
PLATINIZED ANODE
IMPRESS CURRENT ANODES ARE SOMETIMES PACKAGED WITH THE CARBONACEOUS BACKFILL
SACRIFICIAL ANODES
SACP ANODES
MAGENSIUMALUMINIUM
ZINC
ALUMINIUM ANODESZINC ANODE
MAGNESIUM ANODES BACKFILLED MAGNESIUL ANODES
INSTALLATION OF ICCP SYSTEM
DEEP-WELL GB HORIZONTAL SHALLOW GB
DITRIBUTED ANODES
TYPES OF GROUND-BED
Non-metallic vent tube
DEEP WEEL GROUNDBED
One or more anodes installed vertically at a nominal depth of 15 meter (50 ft.) or more below the earth’s surface in a drilled hole for the purpose of supplying cathodic protection for an underground or submerged metallic structure.
CARBON BACKFILL
TO MAINTAIN THE STABILITY OF THE DRILLED HOLE
TO SERVE AS THE PRIMARY ANODIC REACTION SURFACE
TO LOWER THE RESISTANCE TO EARTH OF THE SYSTEM
SHALLOW BED GROUND BED
DEPTH- 3 TO 5 MTR
DISTRIBUTED GROUND BED
ANODE CONNECTION
CABLES FROM ANODE GROUND BED
MAIN CABLE TO +VE TERMINALOF TR
POSITIVE JUNCTION BOX
CP OF ABOVE GROUND NEW TANKS
UNDERTANK WATERING SYSTEM
ICCP Anode Grit
Tank
PVC
Wat
erin
g Pi
pe
To T/R
Compacted Soil
DISTRIBUTED ANODE CP FOR TANKS
CP FOR WELL CASINGS
CP OF TANK INTERNALS
Hanging ICCP anode
ICCP anodePVC Support
CP FOR OFFSHORE JACKETS
CATHODIC PROTECTION CRITERIA
DescriptionPotential vs. Cu/CuSO4
mV
Free Corrosion -700
Zone of Cathodic Protection -900
Intense Corrosion-600
Sever Over-Protection Problems
-1200
Increased Over-Protection -1100
Some Over-Protection -1000
Some Protection -800
CATHODIC PROTECTION MONITORING
Structure to electrolyte Potential measured with a Reference Electrode
For soil – Copper Copper Sulfate
For Sea Water – Silver Silver Chloride
Electrode Placement- i. For Pipelines- on the line @ every 1-2 km ii. For Tanks – Under the tank
CSEPerforated PVC Pipe Filled with Water
Tank
Perforated PVC Pipe Installed for Reference Electrode Placement
AVO
POTENTIAL MEASUREMENT OF OFFSHORE STRUCTURES
Diver with Portable Reference Electrode
POTENTIAL MEASUREMENT OF WELL CASINGS
TP-3TP-1 TP-2
wellTP
TP-3 TP-4
- 850 mV Min. protection levelUn protected
area
Pipe
to so
il pote
ntial
- mV
What about the potential at any point ?
Buried pipeline ( 1.2 meter deep)
Well casing8000 feet deep
The criterion most widely used on pipelines is based on measurementsof potential differences between the pipeline and its environment
.ie: more negative than ( - 850 mv) reference to Cu/Cu So4 cell
MONITORING TEST POSTS
Flush – to – ground
CABLE CONNECTIONS
Prior to welding :The coating must be removed at welding point ( 5x5 cm square ) Metal surface to be polished and cleaned
Pin Brazing Unit
Pistol / Gun
Pins & Ferrules
Lug
Grinder
ELECTRICAL ISOLATION
Structure to be protected should be electrically isolated from the structures which do not require protection
Thank you
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