corrosion control

1. INDUSTRIAL WATER
CORROSION
PRESENTED BY
YASER SALEEM SIDDIQUI
M.TECH – CIVIL(ENVIRONMENTAL ENGG.)
3RD SEMESTER

2. WHAT IS CORROSION?
• CORROSION MAY BE DEFINED AS THE GRADUAL DESTRUCTION OF MATERIALS
WHICH ARE USUALLY METALS DUE TO THEIR CONTACT WITH THE SURROUNDING
ENVIRONMENT.
• IT IS BASICALLY THE CHEMICAL OR ELECTROCHEMICAL DESTRUCTION OF METAL
WITH ENVIRONMENT.
• CORROSION DEGRADES THE METALS THEREBY REDUCING STRENGTH AND
OTHER PHYSICAL AND CHEMICAL PROPERTIES OF METAL.

3. SIGNIFICANCE OF THIS PRESENTATION
• AS FAR AS THE TOPIC OF THIS PRESENTATION IS CONCERNED,WE SHALL DISCUSS
THE PROBLEMS DUE TO CORROSION IN INDUSTRIAL WATER.
• CORROSION HAS VARIOUS EFFECTS ON INDUSTRIAL WATER SUPPLIES.
• THE MAIN PROBLEMS IN INDUSTRIAL WATER SYSTEMS ARE;
1.SCALING
2.CORROSION
3.MICROBIOLOGICAL CORROSION
4.DISPOSAL OF RESIDUAL WASTEWATER
5.BIOFOULING

4. SCALING:
• SCALING OCCURS WHEN THE TEMPERATURE AS WELL AS THE
CHEMICAL CONDITIONS ARE SUCH THAT THE DISSOLVED
MINERAL SALTS WHICH ARE PRESENT IN WATER PRECIPITATE
AND FORM SOLID DEPOSITS.
• SCALING REDUCES THE HEAT EXCHANGE EFFICIENCY AS IT
BECOMES AN INSULATING MEDIUM.
• SCALING CAUSES WASTAGE OF ENERGY.
• SCALING IS RESPONSIBLE FOR INCREASE IN PIPE
WIDTH(DIAMETER),WHICH INCREASES THE LOAD ON THE PUMP.

5. CORROSION:
• CORROSION OCCURS AS A RESULT OF OXIDATION OF
PARENTAL METALS SUCH AS IRON RUSTS.
• THE INTEGRITY OF THE VARIOUS PLANT EQUIPMENTS
IS THEN GRADUALLY COMPROMISED.
• CORROSION CAN BE RESPONSIBLE FOR CAUSING
LEAKS.
• LEAKAGES IN PRESSURISED SYSTEMS MAY BE VERY
DANGEROUS FOR THE PLANT WORKERS.

7. MICROBIOLOGICAL CORROSION:
• UNTREATED COOLING WATER IS WARM AND MAY CONTAIN
ORGANIC NUTRIENTS.
• MICROBES GENERALLY THRIVE IN SUCH WATERS AS THE WET
COOLING TOWERS ARE GOOD AIR SCRUBBERS.
• DUSTS, FUNGAL SPORES, GRASS,FLIES ETC. GET COLLECTED
IN THE WATER AND THEREBY FORM OF ‘MICROBIAL SOUP’ IF
THEY ARE NOT WELL TREATED WITH BIOCIDES.
• DEADLY LEGIONNAIRES' DISEASE IS ALSO CAUSED DUE TO
THE PROBLEM OF UNTREATED COOLING WATERS.

8. DISPOSAL OF RESIDUAL INDUSTRIAL
WASTEWATERS:
• THIS IS ONE OF THE MOST DIFFICULT CHALLENGES WHICH HAS TO BE TACKLED.
• THIS IS DIFFICULT AS WELL AS COSTLY.
• MANY CHEMICAL, PETROCHEMICAL REFINERIES AND PLANTS HAVE AN ARRANGEMENT OF ONSITE
DISPOSAL OF THEIR RESIDUAL WASTEWATERS.
• THE POLLUTANT CONCENTRATION LEVELS OR PERMISSIBLE LIMITS SHALL COMPLY WITH THE
LOCAL/NATIONAL REGULATIONS AS FRAMED BY THE GOVERNMENT SO AS TO DISPOSE THE
WASTEWATER INTO COMMUNITY TREATMENT PLANTS, RIVERS, LAKES OR SEAS.

9. BIOFOULING:
• IT IS A PHENOMENON WHERE WATER SURFACES IN CONTACT
WITH WATER ARE COLONISED BY MICROORGANISIMS.
• CORROSION ASSOCIATED WITH MICROORGANISIMS HAS BEEN
RECOGNISED FOR OVER 50 YEARS.
• BIOFOULING IS A CRITICAL ISSUE IN MEMBRANE WATER AS WELL
AS WASTEWATER TREATMENT.
• BIOFOULING GREATELY COMPROMISES THE EFFICIENCY OF
TREATMENT PROCESSES.
• MEMBRANE FOULING IS A MAJOR PROBLEM ENCOUNTERED IN
MEMBRANE FILTERATION PROCESSES.
• IT IS A MAJOR FACTOR IN DETERMINING THE PRACTICAL
APPLICATION IN WATER AND WASTEWATER TREATMENT AND
DESALINATION IN TERMS OF TECHNOLOGY AND ECONOMICS.

10. ADVERSE EFFECTS OF BIOFOULING:
• MEMBRANE FLUX DECLINE DUE TO FORMATION OF LOW PERMEABILITY BIOFILM
ON THE MEMBRANE SURFACE.
• INCREASED DIFFERENTIAL PRESSURE AND FEED PRESSURE BEING NEEDED TO
MAINTAIN THE SAME PRODUCTION RATE DUE TO BIOFILM RESISTANCE.
• MEMBRANE BIODEGRADATION CAUSED BYACIDIC BY-PRODUCTS WHICH ARE
CONCENTRATED AT THE MEMBRANE SURFACE.

11. CORROSION CONTROL TECHNIQUES:
• BASICALLY THERE ARE FOUR METHODS FOR CORROSION CONTROL
1.COATINGS AND LININGS.
2.CATHODIC PROTECTION(CP)
3.MATERIALS SELECTION.
4.CORROSION INHIBITORS.

12. • COATINGS AND LININGS ARE OFTEN APPLIED IN CONJUNCTION WITH CATHODIC PROTECTION
SYSTEMS IN ORDER TO PROVIDE A COST-EFFECTIVE PROTECTION SYSTEM FOR A STRUCTURE.
• CATHODIC PROTECTION (CP) IS A TECHNIQUE THAT USES DIRECT ELECTRICAL CURRENT IN
ORDER TO COUNTERACT THE NORMAL EXTERNAL CORROSION OF A STRUCTURE, THAT
CONTAINS METAL SUCH AS AN UNDERGROUND PETROLEUM STORAGE TANK OR NATURAL GAS
PIPELINE.
• MATERIAL SELECTION REFERS TO THE SELECTION AND USE OF CORROSION RESISTANT
MATERIALS SUCH AS STAINLESS STEEL, PLASTICS AND SPECIAL ALLOYS TO INCREASE THE LIFE
SPAN OF A STRUCTURE.
• CORROSION INHIBITORS ARE THE SUBSTANCES THAT WHEN ADDED TO A PARTICULAR
ENVIRONMENT,DECREASE THE RATE OF ATTACK OF ENVIRONMENT ON THE MATERIAL SUCH AS
METAL.THEY CAN HELP TO INCREASE THE LIFE SPAN OF A METAL USED AS PIPES OR IN ANY
PART OF A STRUCTURE.

13. EPOXY COATING

14. SOME COMMONLY USED CORROSION
INHIBITORS FOR VARIOUS PURPOSES

15. • THESE CORROSION INHIBITORS INCLUDE
1. ANODIC INHIBITORS
2. CATHODIC INHIBITORS
3. BOTH (FILMING AMINES, PHOSPHATES)
SCALE/DEPOSIT CONTROLLERS:
• CONGLOMERATION OF MANY CONSTITUENTS THAT CAN RANGE FROM SETTLED SOLT FROM
AIR BORNE DUST BLOWN INTO THE COOLING TOWER TO PRECIPITATE.
1.PHOSPHATES
2.PHOSPHONO-CARBOXYLATES
3.ORGANIC ACIDS
4.POLYMERS

16. COOLING WATER SYSTEMS:
• A COOLING SYSTEM IN WHICH WATER IS USED AS A COOLING AGENT TO
PROVIDE COOLING ACTION AND THEREBY LOWER THE TEMPERATURE.
TYPES OF COOLING WATER SYSTEMS:
• THE WATER CAN BE DISCHARGED AT THE INCREASED TEMPERATURE INTO A
RECEIVING BODY ONCE THROUGH COOLING SYSTEM OR IT CAN BE COOLED AND
REUSED(RECIRCULATING COOLING SYSTEM)
• THERE ARE TWO TYPES OF COOLING SYSTEMS NAMELY;
1. OPEN SYSTEMS
2. CLOSED RECIRCULATING SYSTEMS

17. • IN OPEN SYSTEMS COOLING IS ACHIEVED THROUGH EVAPORATION OF A FRACTION
OF THE WATER. EVAPORATION RESULTS IN LOSS OF PURE WATER FROM THE SYSTEM
AND A CONCENTRATION OF REMAINING DISSOLVED. WATER MUST BE REMOVED OR
BLOWN DOWN IN ORDER TO CONTROL THIS CONCENTRATION AND FRESH WATER
MUST BE ADDED TO REPLENISH THE SYSTEM.
• IN CLOSED RECIRCULATING SYSTEMS, THERE IS A COOLING SYSTEM WITHIN A
COOLING SYSTEM. THE WATER CONTAINING HEAT TRANSFERRED FROM THE
PROCESS IS COOLED FOR REUSE BYMEANS OF AN EXCHANGE WITH ANOTHER FLUID.
WATER LOSSES ARE USUALLY SMALL.