1. What are the types of chemical storage tanks used in industries?
Vertical cylindrical tanks, horizontal tanks and underground tanks.
Fixed roof, dome roof and floating roof tanks.
Materials include MS, SS, FRP, HDPE and PP depending on chemical compatibility.
Used for acids, solvents, alkalis, oils and water.
2. What materials are commonly used for chemical storage tank construction?
Mild steel (MS) for non-corrosive or low-corrosive chemicals.
Stainless steel (SS304/SS316) for corrosive and high-purity chemicals.
FRP and HDPE for strong acids, alkalis and corrosive liquids.
Alloy steels for highly aggressive chemicals and high temperatures.
3. What factors are considered while selecting a tank material?
Chemical compatibility with stored liquid.
Operating temperature and pressure conditions.
Corrosion resistance, maintenance needs and service life.
Cost, availability and regulatory requirements.
4. What is the difference between MS, SS and FRP tanks?
MS tanks are low-cost but prone to corrosion without coating.
SS tanks provide excellent corrosion resistance and hygiene.
FRP tanks are lightweight, corrosion-resistant and ideal for acids/alkalis.
Selection depends on chemical properties and application needs.
5. What are vertical vs horizontal storage tanks?
Vertical tanks occupy less footprint and are preferred for large capacities.
Horizontal tanks offer more stability and are used for smaller volumes.
Vertical tanks suit atmospheric storage; horizontal tanks suit skid and transport applications.
6. What is the purpose of a dyke wall around tanks?
Contains spills or leaks from tanks to prevent environmental contamination.
Provides secondary containment as per safety norms.
Dyke capacity typically equals 110% of largest tank volume.
7. What is a double-walled storage tank?
Tank within a tank design used for hazardous chemicals.
Prevents leakage into soil or environment.
Interstitial space often monitored for leak detection.
8. What is the importance of tank venting?
Prevents pressure buildup during filling and vacuum during emptying.
Protects tank from deformation or explosion.
Ensures safe breathing of tank during temperature changes.
9. What are flame arrestors and why used on storage tanks?
Devices that stop external flames from entering tank vapors.
Prevent ignition of flammable vapors inside the tank.
Essential for solvent and fuel storage safety.
10. What are breather valves in storage tanks?
Pressure–vacuum relief valves that maintain safe internal pressure.
Open during filling, draining and thermal expansion.
Prevent tank collapse, over pressurization and vapor loss.
11. What is nitrogen blanketing and why is it required?
Nitrogen blanketing maintains an inert atmosphere above stored chemicals.
Prevents oxidation, moisture ingress and flammable vapor ignition.
Essential for solvents, oils and oxygen-sensitive chemicals.
12. What causes tank over-pressurization?
Rapid filling, blocked vents, thermal expansion or vapor generation.
Malfunctioning pressure–vacuum valves or flame arrestors.
Can lead to tank bulging, cracking or explosion.
13. What causes vacuum formation inside storage tanks?
Fast liquid withdrawal causing sudden pressure drop.
Cooling of vapors inside a sealed tank.
Blocked vent lines or malfunctioning breather valves leading to tank collapse.
14. What is the purpose of a level gauge in tanks?
Measures liquid level for safe filling and operation.
Prevents overflow, dry running and process disruptions.
Types include glass gauge, magnetic level gauge, radar and ultrasonic sensors.
15. What is the difference between float type and radar level sensors?
Float sensors rely on buoyancy and mechanical movement.
Radar sensors use microwave signals for non-contact measurement.
Radar provides higher accuracy, no moving parts and works with corrosive chemicals.
16. What are common failures in chemical storage tanks?
Corrosion, leakage, cracking and joint failure.
Lining damage, vent blockage and structural deformation.
Caused by poor material selection, improper maintenance or chemical incompatibility.
17. What tests are required for tank integrity?
Hydrotest, vacuum box test and dye penetrant test.
Ultrasonic thickness measurement and radiography.
Ensures tank strength, weld quality and corrosion monitoring.
18. What is hydrotest of a storage tank?
Filling the tank with water to check structural strength and leakage.
Conducted as per API 650 / IS standards before commissioning.
Confirms tank integrity under maximum load conditions.
19. What is an LEL sensor in tank farms?
A sensor that detects flammable vapor concentration in air.
Alerts operators when vapors reach hazardous levels.
Critical for solvent tanks to prevent fire or explosion.
20. What safety precautions are required for chemical tank farms?
Firefighting system, foam pourers and hydrants.
Dyke walls, grounding, spill control and gas detectors.
Proper labeling, PPE, emergency exits and regular inspections.
21. What is the purpose of a drain valve in tanks?
Removes accumulated sludge, sediments and water bottom.
Helps in periodic cleaning and maintenance.
Prevents contamination of stored chemical during withdrawal.
22. What is the significance of earthing/bonding in storage tanks?
Prevents buildup of static electricity during filling or emptying.
Protects against sparks that can ignite flammable vapors.
Mandatory for solvent and fuel storage tanks.
23. What is corrosion allowance in tank design?
Extra thickness added to tank shell to compensate for expected corrosion.
Extends tank service life in corrosive environments.
Defined as per design codes and nature of stored chemical.
24. What are tank roof types (cone roof, dome roof, floating roof)?
Cone roof: Fixed, used for non-volatile chemicals.
Dome roof: Withstands internal pressure better, used for gases/vapors.
Floating roof: Reduces vapor losses for flammable liquids like solvents.
25. What is the function of a floating roof tank?
Minimizes vapor space above the liquid, reducing evaporation losses.
Prevents formation of explosive vapor mixtures.
Used widely for storage of petroleum products and volatile solvents.
26. What is API 650 and why is it important?
API 650 is the design standard for welded steel storage tanks.
Ensures tank strength, durability and safety requirements.
Used globally for designing atmospheric storage tanks.
27. What is bund capacity requirement for chemical storage?
Bund (dyke) capacity must be at least 110% of the largest tank volume.
Prevents chemical spread in case of leakage or tank rupture.
Mandatory in chemical, pharma and oil tank farms.
28. What is a spill containment system?
Prevents chemicals from spreading during leaks or overflows.
Includes bunds, trenches and catch basins.
Protects environment and improves safety compliance.
29. Why are manholes provided in storage tanks?
Allow access for cleaning, inspection and maintenance.
Used for internal repairs, sampling and entry.
Designed with gaskets to ensure leak-tight sealing.
30. What is tank mixing and when is it used?
Mixing ensures uniform composition, temperature or density of stored chemicals.
Used for solutions prone to settling or separation.
Achieved using agitators, recirculation pumps or air sparging.
31. What is the function of an agitator on storage tanks?
Maintains uniform mixing of chemicals to prevent settling.
Ensures consistent quality and prevents stratification.
Used for slurries, polymers, emulsions and temperature-sensitive liquids.
32. What are tank linings and coatings?
Protective layers applied inside tanks to prevent corrosion.
Materials include epoxy, rubber lining, glass flake and vinyl ester.
Extend tank life and allow safe storage of aggressive chemicals.
33. Why are FRP linings used inside tanks?
Provide excellent resistance to acids, alkalis and corrosive vapors.
Lightweight and mechanically strong.
Used when MS or SS alone cannot withstand chemical attack.
34. What is a tank calibration chart?
Document showing volume vs. liquid height of the tank.
Used for accurate measurement of stored quantity.
Essential for inventory control and billing purposes.
35. What causes tank leakage?
Corrosion, weld failure, gasket damage or mechanical impact.
Improper lining or material incompatibility.
Prevented through regular inspections and proper tank design.
36. What is the purpose of a vent condenser?
Condenses solvent vapors coming out of the tank vent.
Reduces VOC emissions and prevents chemical loss.
Common for storage of volatile solvents like IPA, MEK and toluene.
37. Why temperature monitoring is required in some tanks?
Prevents overheating or polymerization reactions.
Required for exothermic chemicals and heat-sensitive liquids.
Helps maintain product stability and safety.
38. What is a tank heating coil?
Steam or hot water coil installed inside or outside the tank.
Maintains required temperature for viscous or crystallizing chemicals.
Ensures smooth pumping and uniform product quality.
39. What are insulation and cladding used for?
Insulation reduces heat loss or heat gain.
Cladding protects insulation from weather and mechanical damage.
Essential for temperature-controlled chemicals and outdoor tanks.
40. What is the purpose of a high-level alarm in tanks?
Alerts operators before tank overfilling occurs.
Prevents spills, environmental contamination and safety hazards.
Works with radar, float switches or ultrasonic sensors.
41. Why do some tanks require cooling jackets?
Cooling jackets remove excess heat generated during storage or reactions.
Prevent thermal decomposition, vapor expansion and pressure buildup.
Essential for exothermic chemicals and temperature-sensitive solvents.
42. What is polymer settling and how is it prevented in tanks?
Polymer settling occurs when suspended solids or polymers sink to the bottom.
Leads to uneven product quality and potential pump choking.
Prevented by continuous agitation, recirculation or temperature control.
43. What is the function of a rupture disc in storage tanks?
Provides emergency pressure relief when internal pressure exceeds design limits.
Bursts at a predetermined pressure to prevent tank explosion.
Used as a fail-safe backup to pressure–vacuum valves.
44. Why are secondary containment systems required?
Capture leaks, spills or tank failures to prevent soil and water contamination.
Legally required for hazardous chemical storage.
Includes dyke walls, spill trays and containment basins.
45. What causes tank bottom bulging?
High internal pressure, weakened bottom plate or ground settlement.
Corrosion and under-tank moisture accumulation also contribute.
Indicates structural damage and requires immediate inspection.
46. Why is periodic inspection important for storage tanks?
Detects corrosion, cracks, lining damage and weld defects early.
Ensures tank integrity and compliance with safety standards.
Prevents leakage and costly environmental incidents.
47. What is NDT and which methods are used for tank inspection?
NDT (Non-Destructive Testing) checks tank condition without damage.
Methods include UT thickness testing, radiography, MPT, DPT and vacuum box testing.
Used to assess corrosion, weld quality and structural health.
48. Why is cathodic protection used for underground tanks?
Prevents underground corrosion by making the tank a protected cathode.
Uses sacrificial anodes or impressed current systems.
Extends tank life and prevents leakage into soil.
49. What is the purpose of vent scrubbers for chemical tanks?
Remove harmful vapors such as acid fumes, ammonia or solvents from tank vents.
Prevent environmental pollution and odor issues.
Protect workers and comply with emission norms.
50. What are common hazards in tank farms?
Fire, explosion, toxic vapor release and chemical spills.
Static charge buildup, overfilling and corrosion failures.
Controlled through fire systems, gas detectors, dyke walls and safe operating procedures.