IS 107 SAFETY IN CHEMICAL AND PETROCHEMICAL INDUSTRY SBTET AP IS

7.1 FUNDAMENTALS OF CHEMICAL SAFETY

7.1.1 UN Classification of Hazardous Materials

• UN system of classification for transport and handling of dangerous goods

• Hazard classes based on physical, chemical, and toxic properties

• Labels, placards, and identification numbers for hazard communication

• Global harmonization and compatibility with GHS (Globally Harmonized System)

7.1.2 Safety in Chemical Industry

• Common causes of chemical accidents and preventive strategies

• Hazard identification (HAZID) and risk assessment (HAZOP) techniques

• Importance of standard operating procedures (SOPs) and permits to work

• Handling, storage, and segregation of hazardous chemicals

• Chemical compatibility charts and spill management techniques

7.1.3 Criteria for Siting and Layout of Chemical and Petrochemical Plants

• Selection of plant location: environmental, safety, and community factors

• Minimum safety distances between process units, storage areas, and public zones

• Layout principles to minimize accident impact and ensure safe evacuation

• Fire and explosion risk zoning, wind direction, and access control

• Provision for emergency response centers, assembly points, and firefighting systems

7.1.4 Plant Area Classification

• Division of plant into hazardous and non-hazardous zones

• Classification based on presence of flammable vapors or gases (Zone 0, 1, 2)

• Area classification in accordance with IS/IEC standards

• Control of ignition sources, electrical equipment selection, and earthing practices

7.1.5 Instrumentation for Safe Plant Operations

• Process control systems for safety: alarms, trips, and interlocks

• Pressure relief and shutdown systems

• Gas detection, leak detection, and fire alarm systems

• Emergency shutdown (ESD) and Safety Integrity Level (SIL) concepts

• Instrument calibration and preventive maintenance for reliability

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7.2 PROCESS SAFETY AND HAZARD CONTROL

7.2.1 Hazards in Unit Processes and Unit Operations

• Chemical reaction hazards: exothermic reactions, runaway reactions, polymerization

• Unit operation hazards: distillation, drying, filtration, mixing, storage, and transfer

• Equipment failure modes and effects (FMEA)

• Thermal and mechanical hazards in reactors, heat exchangers, and compressors

7.2.2 Control, Precautions and Prevention in Specific Chemical Industries

• Fertilizer plants: ammonia leaks, fire hazards, toxic gas exposure

• Insecticide & pesticide plants: carcinogenic and toxic exposure control

• Chlor-alkali industry: chlorine handling, hydrogen explosion prevention

• Explosives industry: static electricity control, controlled environment, PPE use

• Polymer plants: monomer storage hazards, reaction control

• Engineering and administrative controls for minimizing risks

7.2.3 Sampling Techniques for Toxic and Flammable Substances

• Safe sampling procedures for liquids, gases, and solids

• Use of closed-loop and purged sampling systems

• Personal protective equipment and gas monitoring during sampling

• Special precautions for toxic, corrosive, or flammable chemicals

• Sampling in pharmaceutical and petrochemical plants — contamination prevention

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7.3 HANDLING OF EXPLOSIVE AND TOXIC MATERIALS

7.3.1 Precautions in Processes and Operations Involving:

• Explosives: control of initiation sources, safe mixing, and storage practices

• Flammables: control of vapor release, grounding, and inert gas blanketing

• Toxic substances: leak detection, neutralization, and emergency isolation

• Dusts and gases: prevention of dust explosions, use of dust collectors and vents

• Vapor cloud formations: dispersion modeling and mitigation measures

• Combating measures: firefighting techniques for chemical fires, use of foam and dry powder, emergency shutdowns, and evacuation procedures

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Here’s the complete section for Unit 7.4 to 7.6 – “Safety in Chemical and Petrochemical Industry”, formatted clearly and professionally in continuation with the previous part:

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7.4 STORAGE AND HANDLING OF CHEMICALS

7.4.1 Receiving, Storing and Handling of Chemicals

• Procedures for safe receiving and inspection of chemical consignments

• Verification of labeling, documentation, and Material Safety Data Sheets (MSDS)

• Segregation of incompatible materials during unloading and storage

• Storage design: ventilation, temperature control, spill containment, and fire protection

• Handling techniques for solids, liquids, and gases (manual and mechanical methods)

• Safe storage of flammable, corrosive, oxidizing, and toxic substances

• Periodic inspection and maintenance of containers, drums, and storage tanks

• Emergency measures for spills, leaks, and accidental releases

• Housekeeping, signage, and use of personal protective equipment (PPE) in storage areas

7.4.2 Chemical Compatibility Considerations

• Importance of chemical compatibility in storage and transfer

• Use of compatibility charts to prevent violent reactions, fires, or explosions

• Segregation of acids, bases, oxidizers, reducers, and organic materials

• Safe use of storage containers and pipelines made of compatible materials

• Monitoring of temperature, pressure, and humidity for reactive substances

• Proper labeling and color coding of chemical storage areas

• Use of secondary containment and neutralization systems for incompatible leaks

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7.5 TRANSPORTATION OF HAZARDOUS MATERIALS

7.5.1 Transportation of Hazardous Material

• Legal framework and regulatory requirements (Motor Vehicle Act, IMDG Code, etc.)

• Classification, packaging, labeling, and documentation as per UN Recommendations

• Responsibilities of consignor, transporter, and consignee

• Vehicle design, route planning, and driver training for hazardous transport

• Inspection and maintenance of transport containers, valves, and fittings

• Emergency response plans and communication systems during transit

7.5.2 Safety Precautions for Transporting Hazardous / Toxic / Flammable / Explosive / Radioactive Substances by All Modes

• Road transport: segregation of loads, vehicle placards, driver rest and emergency drills

• Rail transport: wagon design, labeling, securement, and loading procedures

• Air transport: IATA regulations for dangerous goods, pressure and temperature safety

• Sea transport: IMDG Code compliance, segregation, and spill response equipment

• Pipeline transport: integrity monitoring, leak detection, and automatic shutoff valves

• Radiation shielding, monitoring, and dosimetry for radioactive material transport

• Use of GPS tracking, communication protocols, and escort vehicles for high-risk cargo

• Emergency preparedness: firefighting appliances, first-aid, and spill containment kits

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7.6 TRANSFER OF CHEMICALS BY PIPELINES

7.6.1 Transfer of Chemicals by Pipelines within and Outside Installations (Aboveground, Underground, and Submarine)

• Design standards and materials selection for chemical pipelines

• Classification of pipelines based on pressure, contents, and location

• Layout design — routing, segregation, and accessibility for maintenance

• Safety measures for above ground pipelines: supports, identification, leak detection

• Precautions for under ground pipelines: corrosion protection, cathodic protection, pressure testing

• Submarine pipelines: marine environmental protection, buoyancy control, and coating

• Inspection, testing, and preventive maintenance schedules

• Monitoring systems — pressure gauges, flow sensors, and alarm systems

• Emergency isolation valves and remote shutdown systems

• Procedures for safe transfer, draining, purging, and maintenance

• Documentation and record keeping as per statutory regulations

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7.7 PIPELINE SAFETY AND SAFE WORK PRACTICES

7.7.1 Colour Coding and Identification of Contents

• Colour coding ensures quick identification of pipeline contents to prevent accidents.

• Follow IS 2379:1990 – Colour Code for Identification of Contents in Pipelines.

• Example colour codes:

  • Water – Green

  • Steam – Silver Grey

  • Air – Light Blue

  • Acids – Violet

  • Alkalis – Dark Green

  • Flammable liquids – Brown

  • Toxic/Corrosive – Orange

• Arrows indicating direction of flow must be marked on pipelines.

• Regular inspection and repainting to maintain visibility and accuracy.

• Colour coding must also appear on valves, manifolds, and terminal points.

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7.7.2 Safety Precautions for Working on Pipelines

• Obtain work permit before any maintenance, alteration, or cutting work.

• Isolate the section using blinds, spades, or double block and bleed method.

• Depressurize, drain, and purge the line before starting work.

• Test atmosphere for oxygen and toxic gases prior to hot work or confined space entry.

• Use non-sparking tools, flame arresters, and grounding to prevent static discharge.

• Continuous monitoring during welding, cutting, or mechanical work.

• Clearly display “Men at Work” or “Pipeline Under Maintenance” signage.

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7.7.3 Safe Entry Procedures to Confined Spaces Including Reaction Vessels

• Confined space examples: reactors, tanks, pits, towers, and large pipelines.

• Follow a Confined Space Entry Permit system.

• Steps before entry:

  • Isolate and clean the vessel thoroughly.

  • Test for oxygen (19.5–23.5%), flammable gas (<10% LEL), and toxic vapours (below TLV).

  • Provide forced ventilation to remove residual gases.

  • Workers must wear full-body harness, lifeline, and breathing apparatus.

  • Maintain standby personnel outside for communication and rescue.

  • Continuous monitoring and emergency rescue equipment must be available.

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7.7.4 Safe Procedure of Startup and Shutdown

• Startup:

  • Check readiness of equipment, valves, and control systems.

  • Gradual pressurization and temperature increase to avoid thermal shock.

  • Ensure all safety devices (relief valves, alarms, interlocks) are functional.

  • Strict supervision during chemical charging or line pressurization.

• Shutdown:

  • Stop feed gradually, maintain cooling and venting.

  • Depressurize and purge systems with inert gas (e.g., nitrogen).

  • Isolate and drain process fluids before maintenance.

• Preventive and Emergency Maintenance Safety:

  • Use proper tools and PPE.

  • Follow lockout–tagout (LOTO) procedures.

  • Keep fire-fighting and first-aid equipment ready.

  • Never bypass interlocks or safety valves during maintenance.

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7.8 USE OF MATERIAL SAFETY DATA SHEETS (MSDS)

7.8.1 Importance and Use

• MSDS provides complete hazard information for each chemical used.

• It contains 16 standard sections as per GHS (Globally Harmonized System).

• Key information includes:

  • Chemical identity and manufacturer details

  • Hazard classification (flammable, toxic, corrosive, reactive)

  • Safe handling and storage instructions

  • Exposure limits and PPE requirements

  • First aid, firefighting, and spill control measures

  • Reactivity and stability data

  • Waste disposal and transport information

• Workers must be trained to interpret and apply MSDS information before using chemicals.

• MSDS must be readily accessible in all work areas where chemicals are used or stored.

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7.9 WORK PERMIT SYSTEM AND SPECIAL OPERATIONS

7.9.1 Work Permit System

• A Work Permit System (WPS) ensures control over hazardous maintenance or non-routine jobs.

• Types of permits include:

  • Hot Work Permit – for welding, gas cutting, grinding, etc.

  • Cold Work Permit – for mechanical or non-sparking operations.

  • Confined Space Entry Permit – for entry into tanks, pits, or reactors.

  • Electrical Work Permit – for energized or de-energized systems.

  • Height Work Permit – for scaffolding, roofing, or elevated jobs.

• Key elements:

  • Job description, hazards, and control measures

  • Isolation and LOTO verification

  • PPE and gas test requirements

  • Permit validity time and authorized signatories

  • Supervision and closure after job completion

Confined Space

• Entry only after gas testing and ventilation.

• Lifeline, breathing apparatus, and rescue standby required.

• Continuous monitoring of oxygen, flammable and toxic gases.

Hot Work

• Area must be cleared of combustibles and gas-free certified.

• Use fire watch, fire blankets, and extinguishers nearby.

• Grounding to prevent static discharge.

Working at Height

• Use full body harness, lifeline, and fall arrest systems.

• Proper scaffolding, guardrails, and safe access ladders.

• Weather conditions (rain, wind) must be considered.

• Tools to be secured with tool lanyards to prevent falling.

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7.10 – FIRE AND EXPLOSION SAFETY

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7.10.1 Fire and Explosion

• Fire and explosion are among the most serious hazards in chemical and petrochemical industries.

• These incidents cause major loss of life, property, production, and environment.

• Explosion is a sudden release of energy, resulting in a rapid rise in pressure and temperature.

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7.10.2 Chemistry of Fire and Classification

Chemistry of Fire:

• Fire is a chemical reaction (oxidation) between fuel, oxygen, and heat producing flame, light, and heat.

• Represented by the Fire Triangle (Fuel + Heat + Oxygen).

• The reaction becomes self-sustaining when enough heat is produced to continue vaporization of the fuel.

Factors Contributing to Fire:

• Presence of flammable substances (liquids, gases, vapours, dusts).

• Leakage, poor maintenance, static charge, or open flame.

• Poor ventilation or confined areas.

• Improper electrical connections and overloading.

Classification of Fires (as per IS 2190:2010):

Class	Type of Fire	Examples	Suitable Extinguishing Agent
Class A	Ordinary combustibles	Wood, paper, cloth	Water, foam
Class B	Flammable liquids	Petrol, diesel, oil	Foam, CO₂, DCP
Class C	Flammable gases	LPG, methane	CO₂, DCP
Class D	Metal fires	Sodium, magnesium	Dry powder (special)
Class E	Electrical fires	Cables, motors	CO₂, DCP (non-conductive)
Class F	Cooking oils/fats	Kitchen fires	Wet chemical extinguishers

Common Causes of Industrial Fires:

• Electrical faults, short circuits, overloading

• Static electricity or friction sparks

• Hot work (welding, cutting) near flammable materials

• Poor housekeeping and spillages

• Leakage from pipelines or storage vessels

• Smoking or use of open flames in restricted areas

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7.10.3 Fire Load and Building Design for Fire Safety

Determination of Fire Load:

• Fire load = Total heat energy (in kcal or MJ) released if all combustibles burn per unit floor area.

• Formula:
  [
  \text{Fire Load (MJ/m²)} = \frac{\text{Weight of combustibles (kg)} × \text{Calorific value (MJ/kg)}}{\text{Floor area (m²)}}
  ]

• Helps determine fire resistance, classification, and required fire-fighting system.

Design for Fire Safety:

• Adequate number and width of exits as per National Building Code (NBC Part IV).

• Use of fire-resistant materials for walls, doors, and partitions.

• Fire escape routes clearly marked and illuminated.

• Proper spacing between process areas and storage areas.

• Installation of fire walls, fire doors, and emergency lighting systems.

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7.10.4 Fire Prevention and Extinguishing Systems

Fire Prevention:

• Eliminate ignition sources (spark, heat, flame).

• Control flammable vapor concentration below LEL (Lower Explosive Limit).

• Maintain equipment and ensure leak-proof systems.

• Strict control of smoking, hot work, and static charge.

Types of Fire Extinguishing Systems:

1. Portable Extinguishers:

   • Water, Foam, CO₂, DCP, Wet Chemical types.

   • Used for initial fire control (first aid firefighting).

2. Hydrant System:

   • Network of pipes supplying pressurized water through hydrant valves.

   • Fire pumps (main, jockey, diesel) maintain pressure.

3. Sprinkler System:

   • Automatic water discharge when temperature rises.

   • Used in warehouses, production halls.

4. CO₂ System:

   • For electrical and flammable liquid fires.

   • Non-conductive and leaves no residue.

5. Foam System:

   • For oil and chemical fires; smothers the surface preventing oxygen contact.

6. Dry Chemical Powder (DCP) System:

   • Suitable for Class A, B, and C fires.

   • Breaks the chemical chain reaction.

7. Halon Replacement Agents:

   • Halon phased out due to ozone depletion.

   • Replaced by FM-200, FE-36, Novec 1230 gases.

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7.10.5 Fire Detection and Alarm System

• Early detection minimizes damage and allows timely evacuation.

• Types of detectors:

  • Smoke Detectors: Ionization or optical type.

  • Heat Detectors: Fixed temperature or rate-of-rise type.

  • Flame Detectors: Infrared or ultraviolet sensing.

• Alarm systems:

  • Audible (sirens, bells), visual (flashing lights).

  • Linked to central fire control room.

• Automatic fire alarm system integrated with sprinklers and emergency shutdowns (ESD).

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7.10.6 Safety Precautions for Handling Flammable Materials

• Use inert gas blanketing (nitrogen) for flammable liquids.

• Grounding and bonding to prevent static ignition.

• Ventilation to prevent accumulation of vapours.

• Avoid welding or hot work near flammable storage.

• Dust Explosion: Prevent dust accumulation, use explosion vents.

• BLEVE (Boiling Liquid Expanding Vapour Explosion):

  • Caused by rupture of pressurized vessel containing superheated liquid.

  • Prevent by pressure relief valves and proper cooling.

• Vapour Cloud Explosion (VCE):

  • Occurs when flammable vapour cloud ignites after spreading over a large area.

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7.10.7 Fire Emergency Action Plan

• Alarm and Communication: Activate fire alarm, inform control room.

• Evacuation: Follow emergency escape routes; assembly points pre-identified.

• Firefighting: Trained teams with PPE and extinguishers.

• Medical Aid: Provide first aid to affected persons.

• Deflagration: Slow combustion (subsonic flame speed).

• Detonation: Fast combustion with supersonic flame propagation and high pressure wave.

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7.11 – FIRE AND EXPLOSION INDEX, PRESSURE VESSEL SAFETY

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7.11.1 Fire, Explosion and Toxicity Index

DOW Fire and Explosion Index (F&EI):

• Developed by Dow Chemical Company to estimate potential fire/explosion risk.

• Based on process materials, operating conditions, and equipment layout.

• Steps:

  1. Determine Material Factor (MF) (based on chemical flammability/reactivity).

  2. Apply Penalty Factors for process hazards.

  3. Calculate F&EI = MF × (Penalty Factors).

  4. Evaluate Damage Potential and Area of Exposure.

• Used for insurance, plant layout design, and risk prioritization.

Toxicity Index:

• Indicates potential hazard of chemicals due to toxicity or exposure risk.

• Based on IDLH, TLV, and LD₅₀ values.

Dispersion and Probability Analysis:

• Models used to predict the spread of toxic or flammable vapours (e.g., ALOHA, PHAST).

• Probability analysis helps estimate likelihood of accidents and risk ranking.

• Modeling supports emergency planning and zoning decisions.

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7.11.2 Pressure Vessels (Fired and Unfired)

• Fired vessels: Boilers, heaters – use direct flame for heating.

• Unfired vessels: Reactors, separators, air receivers – not exposed to direct flame.

• Governed by Static and Mobile Pressure Vessel Rules, 1981 (amended 2000) and ASME Section VIII.

• Safety aspects:

  • Design pressure ≥ operating pressure + safety margin.

  • Fitted with safety valves, pressure gauges, temperature indicators.

  • Periodic inspection and hydrotesting as per statutory norms.

  • Relief valves tested and calibrated regularly.

  • Proper earthing to prevent static discharge.

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7.12 – RELIABILITY AND TESTING OF PRESSURE VESSELS

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7.12.1 Assessment of Reliability of Vessels

• Reliability means the probability that a vessel will perform its function safely during its service life.

• Factors influencing reliability:

  • Design quality and material selection.

  • Fabrication methods and welding quality.

  • Corrosion, fatigue, creep, and thermal stresses.

  • Inspection frequency and maintenance practices.

Test Checks and Inspections:

• Visual Inspection: For cracks, leaks, corrosion, or deformation.

• Non-Destructive Testing (NDT):

  • Ultrasonic testing (UT) – thickness, defects.

  • Radiography (RT) – weld integrity.

  • Magnetic particle (MPT) and Dye penetrant (DPT) tests.

  • Hydrostatic test – pressure test using water.

  • Pneumatic test – for leak detection using air/nitrogen.

• Periodic Re validation: As per statutory requirements (Factories Act and SMPV Rules).

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7.13 INSPECTION AND MAINTENANCE IN CHEMICAL INDUSTRIES

7.13.1 Inspection Techniques for Plants and Reaction Vessels

Purpose of Inspection:

• To ensure safety, reliability, and efficiency of equipment.

• To detect corrosion, cracks, wear, leaks, or other deterioration.

• To prevent accidents, breakdowns, and environmental releases.

Types of Inspection:

1. Visual Inspection:

   • External and internal examination for corrosion, leakage, or deformation.

   • Carried out regularly during maintenance shutdowns.

2. Non-Destructive Testing (NDT):

   • Ultrasonic Testing: Detects internal flaws and thickness of vessels/pipes.

   • Radiographic Testing (X-ray/Gamma ray): Checks weld quality and hidden cracks.

   • Magnetic Particle Testing: Detects surface/sub-surface cracks in ferrous materials.

   • Dye Penetrant Test: Used for detecting surface cracks in non-porous materials.

   • Eddy Current Testing: Detects flaws in conductive materials.

3. Pressure Testing (Hydrostatic/Pneumatic):

   • To ensure vessel integrity and leak tightness.

4. Vibration and Thermography Monitoring:

   • For rotating machinery and electrical equipment health assessment.

5. Corrosion Monitoring:

   • By corrosion coupons, probes, and thickness measurement.

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Checklist for Routine Inspection

Equipment	Inspection Points
Storage Tanks	Leakage, corrosion, venting, pressure relief valves, earthing connections
Reactors & Vessels	Lining condition, temperature/pressure gauges, agitators, relief devices
Pipelines	Color coding, identification tags, joints, supports, insulation, leakage
Valves & Flanges	Tightness, packing, operation ease, lubrication
Pumps & Compressors	Alignment, vibration, seals, noise, lubrication, motor condition
Instrumentation	Calibration, alarms, interlocks, emergency shutdown systems
Safety Devices	Fire extinguishers, hydrants, safety showers, eyewash stations

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Checklist for Specific Maintenance and Breakdown

• Isolation and lockout of affected equipment (LOTO procedure).

• Purging, cleaning, and gas-free certification before entry.

• Confined space entry permit with continuous gas monitoring.

• Verification of replacement spares’ quality and compatibility.

• Reassembly inspection before recommissioning.

• Post-maintenance testing — pressure, leak, vibration, and function tests.

• Documentation of maintenance activity and inspection records.

• Root cause analysis for repeated failures.

Importance:
Proper inspection and preventive maintenance minimize unplanned shutdowns, improve safety, and ensure compliance with statutory regulations.

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7.14 CORROSION AND ITS PREVENTION

7.14.1 Corrosion: Definition and Types

Definition:
Corrosion is the gradual destruction of a material (usually metal) due to chemical or electrochemical reactions with its environment.

Types of Corrosion:

1. Uniform Corrosion: Even metal loss over entire surface.

2. Galvanic Corrosion: Occurs between two dissimilar metals in contact with an electrolyte.

3. Pitting Corrosion: Localized attack forming pits or holes.

4. Crevice Corrosion: Occurs in confined spaces where stagnant solution is present.

5. Intergranular Corrosion: Along grain boundaries due to impurities.

6. Stress Corrosion Cracking (SCC): Cracks caused by tensile stress and corrosive environment.

7. Erosion Corrosion: Accelerated corrosion due to high fluid velocity.

8. Microbial Corrosion (MIC): Caused by bacteria or microorganisms.

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Corrosion Locations in Chemical Plants

• Storage Tanks: At bottom due to water/chemical accumulation.

• Pipelines: At bends, joints, and underground sections.

• Heat Exchangers: On tube surfaces due to scaling and pitting.

• Reaction Vessels: Internal walls due to aggressive media.

• Cooling Towers: Due to humid and oxygen-rich environment.

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Causes of Corrosion

• Presence of moisture, oxygen, and corrosive chemicals (acids, alkalis).

• Poor material selection.

• Inadequate protective coating or insulation.

• Galvanic coupling between dissimilar metals.

• Improper design leading to stagnant zones or crevices.

• High temperature or pressure accelerating reaction rate.

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Inspection Methods for Corrosion

• Visual Inspection for rust, pitting, scaling.

• Ultrasonic Thickness Measurement.

• Radiographic Test for internal corrosion.

• Corrosion Coupons/Probes for rate monitoring.

• Electrochemical Measurement (Potential readings).

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Prevention of Corrosion

1. Material Selection:

   • Use of stainless steel, non-ferrous alloys, or corrosion-resistant materials.

2. Protective Coatings:

   • Painting, galvanizing, epoxy, or rubber lining.

3. Cathodic Protection:

   • Sacrificial anode or impressed current system for buried pipelines and tanks.

4. Corrosion Inhibitors:

   • Chemical additives that slow down corrosion rate.

5. Design Improvement:

   • Avoid crevices, ensure drainage, and allow easy cleaning.

6. Environmental Control:

   • Reduce humidity, temperature, or chemical concentration.

7. Regular Inspection and Maintenance:

   • Early detection and timely repairs prevent major failures.

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✅ Summary:

• Regular inspection and preventive maintenance ensure equipment safety.

• Corrosion is a major cause of plant failure—must be monitored and controlled.

• Proper material selection, coatings, and cathodic protection increase equipment life and reduce risk of leaks or explosions.