2 INTRODUCTIONCorrosion is the destruction of metals and alloys by the chemical reaction with the environment.Generally many traditional metal parts are used with lighter polymeric components but these are impervious to electrochemical corrosion so even with the proper selection of base metals, there is no absolute way to eliminate corrosion
5 Zones Of Corrosion Of Steel PileS Marine pile revealing several distinct areas of attack.
6 Corrosion management Before deciding on the methods for control of corrosion to be applied, conceptual and feasibility studies have been carried out. Typically, corrosion management can be divided into three major phases.Phase 1Phase 2Phase 3
7 Flow chart showing various phases in corrosion management.
8 CORROSION MANAGEMENT PHASE 1 Phase 1 of the program is the programmatic assessment or planning stage of the project.For the planning stage, three main requirements sought, budget and schedule needed to overcome the problem raised from corrosion of reinforcement.PHASE 1
9 Phase 2 of the program involves physical assessment and actual remediation. Inspections for severity of corrosion are conducted in this phase to determine what strategy or methods are most suitable to be applied.PHASE 2
10 Phase 3 of the program mainly deals with future monitoring of the repaired structure. Systematically identifying and managing the existing resources can be done by implementing internal or external monitoring system using current technology.PHASE 3
11 CORROSION PROTECTION METHODS CATHODICPROTECTIONPROTECTIVECOATINGANODE DELIVERY SYSTEMAPPLICATION OF FRP COMPOSITES
12 PROTECTIVE COATINGIn order to protect metals from corrosion, the contact between the metal and the corrosive environment is to be cut off. This is done by coating the surface of metals with a continuous non-porous material inert to the corrosive atmosphere.
13 Surface coatings are broadly classified into three Metallic coatingsInorganic CoatingsOrganic Coatings
14 CATHODIC PROTECTIONCathodic protection is an electrochemical process which halts the corrosion of metals in a particular environment by superimposing an electrochemical cell more powerful than the corrosion cell.Sacrifical Anodes are fitted or bonded to the metal to be protected.The implementation is simple, all you need is an anode, a power supply and engineering talent.
15 Figure showing the arrangement of cathodic protection
16 ANODE DELIVERY SYSTEMThese are similar to the cathodic protection method in philosophy.These are designed on the design basis of maximum current distribution for the lowest possible cost, with the most long-term reliability.
19 APPILICATIONS OF FRP COMPOSITES The poor durability of conventional corrosion repairs has led to increased interest for its replacement by fiber reinforced polymers.Although dry conditions are favorable but availability of resins that can cure in water has made it possible.Saturating FRP with resin and installing is complex but benificial in costly repairs and rapid deterioration.
20 Fibre reinforced polymers have long been used for the repair and retrofit of concrete structural elements.Lightweight, high strength andresistance to chemicals.Unparallel flexibility, multi-directional.
21 FRP WRAPPINGIn this method various wrapping materials which reduce the surface contact are wrapped around the piles.
22 STANDARDS AND CODESThere are no Indian standards codes as such for the control of corrosion. The latest editions of the following organizations’ standards, codes, and guidelines shall be used for the design of corrosion control systems: • NACE International (formerly The National Association of Corrosion Engineers) • RP0169 – Control of External Corrosion on Underground or Submerged Metallic Piping Systems
23 CONCLUSIONThough there is no absolute way to eliminate all corrosion on underwater piles, there are some effective measures to control them.