Recommendations for maintenance and operation of petroleum storage tanks, Part 1:Preparation of tanks for safe entry and work

IS 9964 Part 1 - Scope Summary & Key Specifications

Scope:

• Covers design, fabrication, and inspection of atmospheric storage tanks only.
• Emphasis on safety during tank cleaning and maintenance, especially for tanks with leaded products.

Key Safety & Cleaning Specifications (Clause 19.8 & Appendix A)

• Tank plates scrap disposal: Must be heated or grit/shot blasted to remove scale and lead dust contamination.
• Grit/shot blasting: Collect and treat used grit as contaminated; do not reuse.
• Tank cleaning checklist includes:
  • Hazard review by supervisors.
  • Work permit system adherence.
  • Special precautions for leaded product tanks.
  • Use of respiratory protection and gas testing.
  • Complete removal of hydrocarbons before cleaning.
  • No water introduction until oil temperature < 100°C.
  • Use steam/air pumps preferred over electrical pumps.
  • Prevent vapor contact with ignition sources.
  • No tank entry until all lines blinded and gas readings zero.
  • Stand-by personnel during entry.
  • No entry if vapor concentration > 20% of lower explosive limit.

Important Notes

• The standard excludes pressurized or vacuum tanks.
• Safety during cleaning and maintenance is a major focus.
• Refer to Petroleum Rules 1976 for electrical classification in hazardous areas.

flowchart TD
    A[Start Tank Cleaning] --> B{Hazard Review Done?}
    B -- No --> C[Stop Work]
    B -- Yes --> D[Remove Hydrocarbons]
    D --> E{Oil Temp < 100°C?}
    E -- No --> F[Wait]
    E -- Yes --> G[Gas Testing & Ventilation]
    G --> H{Gas < 20% LEL?}
    H -- No --> F
    H -- Yes --> I[Permit & PPE Ready]
    I --> J[Entry with Stand-by]
    J --> K[Complete Cleaning]
    K --> L[Exit & Seal Tank]

For detailed design formulas and fabrication requirements, refer to other parts of IS 9964 and related IS codes (e.g., IS 803, IS 2825).

IS 9964 Part 1 focuses on atmospheric petroleum storage tanks, primarily covering their maintenance and operation.

Types of Petroleum Storage Tanks (per IS 9964 Part 1)

• Fixed Roof Tanks: Simple, with a rigid roof fixed to the shell.
• Floating Roof Tanks: Roof floats on the liquid surface to minimize vapor losses (Clause 4.3).
• Open Top Tanks: No roof, used for certain storage needs.

Key Specifications:

• Only atmospheric tanks are covered (Clause 1.1.2).
• Floating roofs reduce vapor losses by eliminating vapor space or keeping it constant.
• Compliance with Factory Act 1948 and Petroleum Act for safety during maintenance (Clause 3.1).

Typical Formulas (General Reference):

• Vapor space volume in fixed roof tanks:
  [ V_v = \pi r^2 h_v ] where (r) = tank radius, (h_v) = vapor space height.

• Floating roof eliminates vapor space, reducing (V_v \to 0).

Summary Table of Tank Types:

flowchart LR
    A[Petroleum Storage Tanks] --> B[Fixed Roof Tanks]
    A --> C[Floating Roof Tanks]
    A --> D[Open Top Tanks]
    C --> E[Minimize Vapor Loss]
    B --> F[Simple Construction]
    D --> G[High Vapor Loss]

For detailed design and maintenance, refer to statutory safety acts and IS 9964 operational clauses.

IS 9964 Part 1 - Statutory Requirements Summary

Key Statutory References (Clause 3.1)

• Compliance with Factory Act 1948 and Petroleum Act & associated rules is mandatory for:
  • Cleaning
  • Safe entry
  • Repair & maintenance of petroleum storage tanks.

Tank Cleaning & Safe Entry Checklist (Appendix A, Clause 17.1)

• Hazard review by supervisors & engineers.
• Work permit system enforced.
• Special precautions for tanks with leaded products.
• Respiratory protection & gas testing equipment in good condition.
• Complete removal of hydrocarbons before cleaning.
• Avoid water introduction until oil temperature < 100°C.
• Use steam/air-driven pumps outside firewalls; follow electrical classification for hazardous areas.
• Prevent vapor contact with ignition sources.
• Blind all lines before entry.
• Entry prohibited if flammable vapor > 20% LEL.
• Stand-by personnel during tank entry.
• Ensure zero combustible gas readings before hot work.
• Confirm no personnel/material inside before sealing tank.

Safety for Scrap Disposal (Clause 19.8)

• Tank plates safe for scrap only after:
  • Heating (flame cleaning), OR
  • Removal of scale by grit/shot blasting.
• Collect and treat grit/shot as contaminated if lead dust is present.

Important Safety Limits

Visual Summary: Tank Cleaning Safety Workflow

flowchart TD
    A[Review Hazards] --> B[Work Permit System]
    B --> C[Remove Hydrocarbons]
    C --> D[Check Oil Temp < 100°C]
    D --> E[Gas Testing Equipment Ready]
    E --> F[Blind All Lines]
    F --> G[Check Vapor < 20% LEL]
    G --> H[Entry with Respiratory Protection]
    H --> I[Stand-by Personnel Present]
    I --> J[Perform Cleaning & Repairs]
    J --> K[Confirm Zero Gas Reading Before Hot Work]
    K --> L[Seal Tank]

For detailed procedures and safety compliance, always refer to IS 9964 Part 1 and relevant statutory acts.

IS 9964 Part 1 (1981) — Tank Construction & Roof Types

Roof Types & Key Specs

Important Specifications

• Umbrella & Dome Roofs: Usually limited to ≤ 20 m diameter due to structural complexity.
• Floating Roofs: Used to reduce vapor losses by eliminating or maintaining constant vapor space.
• Safety: For thin roof plates, distribute worker load using planks (Clause 12.5).

Typical Structural Considerations

• Roof Plate Thickness: Depends on diameter, roof type, and loading.
• Meridian Arches: Umbrella roofs use segmental arches for self-support.
• Spherical Curvature: Dome roofs use spherical sections for self-supporting strength.

flowchart LR
    A[Tank Types] --> B[Cone Roof (≤75m)]
    A --> C[Umbrella Roof (≤20m)]
    A --> D[Dome Roof (≤20m)]
    A --> E[Floating Roof (variable)]
    C & D --> F[Self-supporting curved plates]
    E --> G[Minimize vapor loss]

For detailed design, refer to IS 9964 tables for plate thickness, joint design, and wind/snow loads.

Hazards in Tank Cleaning (IS 9964 Part 1)

Key Hazards (Clause 8.1 & 5.2)

• Physical hazards: slipping, falling objects, falls from roofs, improper scaffolding.
• Health hazards: exposure to toxic gases, hydrocarbons.
• Fire hazards: ignition sources from residual vapors.

Tank Cleaning Operations (Clause 9.1)

1. Preliminary preparations: external inspection, crew training, equipment check.
2. Control ignition sources: eliminate sparks, static electricity.
3. Emptying tank: pump out oil, blank off tank.
4. Vapour-freeing: ventilate to remove hydrocarbon vapors.
5. Testing: check for hydrocarbon vapors and toxic gases.
6. Opening and sludge removal: safe entry and disposal.

Important Specifications

• Testing for vapors: Use calibrated gas detectors; ensure below Lower Explosive Limit (LEL).
• Ventilation: Continuous forced ventilation until safe atmosphere is confirmed.
• Safety measures: Use of PPE, harnesses, and safety nets for fall protection.

Summary Table: Hazards & Controls

flowchart TD
    A[Start Cleaning] --> B[Preliminary Inspection]
    B --> C[Control Ignition Sources]
    C --> D[Empty Tank & Blank Off]
    D --> E[Vapour-Freeing & Ventilation]
    E --> F[Gas Testing]
    F --> G[Safe Entry & Sludge Removal]

Follow strict planning, inspection, and training as per IS 9964 Part 1 for safe tank cleaning.

IS 9964 Part 1 (1981) – Atmospheric Conditions & Safe Breathing Limits

Key Specifications:

• Oxygen Content: Minimum safe oxygen level inside tanks is 19.5% for entry without respiratory equipment (Clause 6.1.3.2).
• Ventilation: Must ensure removal of flammable/toxic vapors and maintain oxygen above 19.5% (Clause 6.1.4.1).
• Gas Testing: Use portable, approved meters for:
  • Combustible gas
  • Toxic gas
  • Oxygen levels

Safe Exposure Limits for Aromatic Hydrocarbons (Clause 6.1.1.2):

• Special detection methods like gas spectrometry or gas-liquid chromatography are required for aromatic vapors.

Summary Flow for Safe Entry:

flowchart TD
    A[Start: Prepare for Tank Entry] --> B[Ventilate Tank]
    B --> C[Measure Gas Levels]
    C --> D{Oxygen ≥ 19.5%?}
    D -- Yes --> E[Check Toxic & Flammable Vapors]
    D -- No --> F[Continue Ventilation]
    E --> G{Vapors < Safe Limits?}
    G -- Yes --> H[Entry Allowed without Respiratory Gear]
    G -- No --> I[Use Respiratory Equipment or Delay Entry]

Always confirm gas tests before entry to prevent exposure to toxic or flammable atmospheres.

IS 9964 Part 1: Sources of Ignition & Static Electricity

Key Points from Clauses 7.1.3, 7.2.1 & 7.3

• Sources of Ignition:

  • Open flames, sparks from non-explosion-proof electrical tools, defective cords.
  • Lightning and static electricity discharges on liquid surfaces.
  • Pyrophoric iron polysulphide deposits in sour stock tanks can spontaneously ignite on air exposure.

• Static Electricity Hazards (Clause 7.3):

  • Steam used for gas-freeing tanks can carry charges.
  • Charges on steam nozzles controlled by bonding.
  • Charges may accumulate on insulated metallic objects inside tanks → spark risk.
  • Spark discharge within steam clouds is unsubstantiated.

• Precautions for Sour Stock Tanks (Clause 7.2.1):

  • Prevent air entry until surfaces are wetted.
  • Keep interior surfaces wet until gas-free.

Practical Specifications & Controls

Static Electricity Control Formula (Bonding Resistance)

To avoid spark generation, bonding resistance ( R_b ) should be low enough:

[ R_b \leq \frac{V_{spark}}{I_{max}} ]

Where:

• ( V_{spark} ) = Minimum spark voltage (depends on gas mixture)
• ( I_{max} ) = Maximum allowable leakage current (mA)

flowchart LR
    A[Steam Nozzle] -->|Bonding| B[Grounded Metal]
    B --> C[No Spark Risk]
    A --> D[Steam Charges]
    D --> E[Insulated Metal Object]
    E -->|Charge Accumulation| F[Spark Risk]

Summary: Control static electricity by bonding & grounding, avoid ignition sources, and take special care with sour stock tanks to prevent pyrophoric ignition.

IS 9964 Part 1: Physical Hazards in Tank Cleaning

Key Points on Physical Hazards (Clause 8.1 & related)

• Physical hazards include:
  • Slipping on wet or oily surfaces
  • Falling objects inside or outside the tank
  • Falling from or through tank roofs
  • Improper scaffolding or support structures

Safety Specifications:

• Scaffolding: Must comply with safe load capacity and proper anchorage.
• Fall Protection: Use guardrails, safety nets, or personal fall arrest systems when working at heights.
• Surface Conditions: Ensure non-slip surfaces or use anti-slip mats.
• Object Handling: Secure loose objects and tools to prevent falling.

No direct formulas are specified for physical hazards in IS 9964, but general safety design follows:

General Engineering Notes on Fall Protection:

• Fall arrest force limit: ≤ 6 kN
• Minimum guardrail height: 1.0 m above working platform
• Scaffolding load: Designed for at least 4 kN/m² live load

flowchart TD
    A[Physical Hazards] --> B[Slipping]
    A --> C[Falling Objects]
    A --> D[Fall from Height]
    A --> E[Improper Scaffolding]
    B --> F[Anti-slip surfaces]
    C --> G[Secure tools]
    D --> H[Guardrails, harness]
    E --> I[Load checks, inspections]

Summary: Control physical hazards by proper planning, safe scaffolding, fall protection, and housekeeping as per IS 9964 and related IS codes.

IS 9964 Part 1: Key Points for Tank Cleaning Operations

Major Steps (Clause 9.1)

1. Preliminary Preparations
   • External tank inspection and area survey
   • Crew training and equipment inspection
2. Control Ignition Sources
3. Emptying Tank
   • Pumping and floating oil out
   • Blanking-off tank after oil removal
4. Vapour-Freeing
5. Testing for Hydrocarbon Vapour & Toxic Gas
6. Opening Tank & Sludge Removal

Sludge Removal Methods (Clause 15.2)

• Sweep sludge into piles → shovel into buckets/wheelbarrows
• Wash down tank with water hose (velocity ≤ 1 m/s)
• Use floor-level manways for flushing if available
• Use self-priming pumps or water-operated ejectors if no manways

Safety & Preparation (Clause 8.1, 17.1)

• Beware physical hazards (slipping, falling objects, scaffolding)
• Use checklist (Appendix A) to confirm tank safety before entry

Important Specifications Summary

flowchart TD
    A[Start: Preliminary Prep] --> B[Control Ignition]
    B --> C[Empty Tank (Pump & Float)]
    C --> D[Blank Off Tank]
    D --> E[Vapour-Freeing]
    E --> F[Test for Vapours & Toxic Gas]
    F --> G[Open Tank & Remove Sludge]
    G --> H[Dispose Sludge Safely]

This structured approach ensures safe and effective cleaning per IS 9964 Part 1 guidelines.

IS 9964 Part 1 (1981) — Gas Freeing and Ventilation: Key Points

Ventilation Requirements (Clause 6.1.4 & 6.1.4.1)

• Ventilation must prevent unsafe levels of flammable/toxic vapours and oxygen deficiency.
• Use approved portable meters for:
  • Combustible gas detection
  • Toxic gas detection
  • Oxygen level measurement
• Knowledge of tank contents is essential to determine testing needs.

Gas-Freeing Hazards (Clause 11.1)

• Gas freeing releases inflammable/toxic vapours.
• Vapours can travel 45-50 meters or more, extending danger zones.
• Continuous monitoring near ignition sources is mandatory.

Ventilation Methods (Clause 13.2)

• Forced ventilation via air/steam-driven eductor at lower tank manholes recommended.
• Avoid working on the roof of tanks that are empty but not gas-free to prevent sparks.
• Natural ventilation is allowed by removing roof and shell manhole covers in sequence for free airflow.

Summary Table of Ventilation Safety

flowchart LR
    A[Gas-Freeing Tank] --> B[Release of Vapours]
    B --> C{Vapour Movement}
    C -->|Upwards| D[Roof Manholes]
    C -->|Outwards| E[Danger Zone ≥ 45m]
    D --> F[Forced Ventilation with Eductor]
    E --> G[Personnel Safety Zone]
    F --> H[Safe Atmosphere Inside Tank]
    G --> I[Respiratory Equipment Required]

Note: Always follow statutory authority approvals for instruments and procedures.

Explosion-Proof Equipment Usage (IS 9964 Part 1)

• Clause 11.3:

  • Portable lights, electric motors, and switch gears outside the tank in vapor paths must be explosion-proof.
  • Use explosion-proof extension cords with approved connectors.
  • Equipment must be thoroughly inspected to ensure no ignition sources.

• Key Safety Checks:

  • Gas testing (Clause 6.1.4.1 & 14.2) with combustible gas, toxic gas, and oxygen indicators is mandatory before and during work.
  • Ventilation must maintain vapor concentration below 5% of LFL (Lower Flammable Limit) for entry without respiratory gear.
  • Entry with independent air supply respiratory equipment allowed up to 20% LFL for cold work only.
  • No entry allowed if vapor concentration exceeds 20% LFL.

Summary Table: Entry Conditions Based on Vapor Concentration

Inspection & Equipment Specifications:

• Explosion-proof equipment per IS standards.
• Approved connectors and cords.
• Regular inspection to prevent ignition sources.

flowchart TD
    A[Outside Tank Vapor Path] --> B[Explosion-Proof Equipment]
    B --> C[Inspection: No Ignition Source]
    C --> D{Gas Testing}
    D -->|<5% LFL| E[Entry without Respirator]
    D -->|5-20% LFL| F[Entry with Air Supply Respirator]
    D -->|>20% LFL| G[No Entry Allowed]

Note: Use canister masks only outside tanks; they do not protect against high vapor or oxygen deficiency (Clause 10.3).

IS 9964 Part 1: Emptying and Blanking Off Tanks - Key Points

1. Procedure for Blanking Off (Clause 12.3 & 12.2)

• Close valves nearest to the tank on all connected lines.
• Drain or flush all lines entering the tank before breaking connections.
• Break connections and insert spades (blanks) in all lines to prevent vapor or liquid ingress.
• If blanking is not possible, fill dead ends with water or test lines individually.
• Close valves outside firewalls nearest to the tank.

2. Safety Specifications (Clause 11.3)

• Use explosion-proof portable lights, motors, and switchgear outside the tank in vapor paths.
• Connect equipment with approved explosion-proof extension cords.
• Thoroughly inspect equipment to ensure no ignition source.

3. Important Notes

• Residual oil should be removed as far as practicable before blanking.
• Floating roof tanks (Clause 4.3) reduce vapor losses by maintaining minimal vapor space.

Summary Table: Blanking Off Steps

flowchart TD
    A[Close Valves Nearest to Tank] --> B[Drain/Flush Lines]
    B --> C[Break Connections]
    C --> D[Insert Spades (Blanks)]
    D --> E[Ensure Explosion-Proof Equipment]

This ensures safe isolation of the tank from connected pipelines and prevents vapor or liquid ingress during maintenance or emergency.

IS 9964 Part 1: Vapour Testing Procedures - Key Points

Steam Ventilation (Clause 13.4)

• Minimum tank temperature: 77°C (170°F) to effectively expel vapours.
• Steam quality: Use dry or superheated steam only. Avoid wet steam to prevent static charge and sparking.
• Static electricity hazard: Steam flow can generate static; bond steam pipe/nozzle to tank.
• Steam introduction: Near tank bottom; roof manway/gauge hatch must remain open to prevent pressure build-up or vacuum.
• Vacuum venting: Ensure sufficient venting during rapid steam condensation.

Vapour-Freeing & Testing (Clauses 13.1, 14, 15.3)

• Vapour-freeing: Complete replacement of hydrocarbon vapours with fresh air.
• Area evacuation: Only enter for occasional vapour testing.
• Continuous ventilation: Maintain forced ventilation until all sludge/oil removed.
• Repeat tests: Before re-entry after breaks or interruptions.
• Test gases: Hydrocarbon vapours and hydrogen sulphide must be monitored.

Summary Table: Steam Ventilation Parameters

flowchart LR
    Steam[Steam Supply (Dry/Superheated)]
    TankBottom((Tank Bottom))
    TankRoof((Roof Manway/Gauge Hatch Open))
    Venting((Vacuum Venting))

    Steam -->|Bonded Pipe| TankBottom
    TankBottom --> Tank
    Tank --> TankRoof
    Tank --> Venting

Note: Always follow safety protocols for static control and vapour testing to prevent ignition hazards during vapour-freeing operations.

IS 9964 Part 1 (1981) - Detection of Toxic Gases: Key Points

1. Gas Testing Requirements (Clause 6.1.4.1)

• Use approved portable meters:
  • Combustible gas indicator
  • Toxic gas indicator
  • Oxygen indicator
• Testing must be based on knowledge of tank contents.
• Ensure ventilation prevents unsafe vapour concentration and oxygen deficiency.

2. Safe Exposure Limits for Aromatic Hydrocarbons (Clause 6.1.1.2)

• Use gas spectrometry or gas-liquid chromatography if aromatics suspected.

3. Toxicity Expression & Protective Measures (Clause 6.2.2)

• Toxicity expressed as Threshold Limit Value (TLV)
• Example: Volatile organo-lead compounds TLV = 75 µg/m³ lead
• Ventilation alone may not reduce toxic vapours to safe levels.
• Use respiratory and protective clothing when entering tanks with toxic vapours.

4. Flammable Vapour Limits for Hot Work (Clause 7.1.2)

• Remove flammable liquids and purge vapours to < 1% of Lower Flammable Limit (LFL)
• Vapour content at 14-20% LFL corresponds to zero on combustible gas indicator.
• Note: 1% LFL ≈ 10,000 ppm (unsafe for breathing).

Summary Table: Safe Gas Concentrations & Equipment

flowchart LR
    A[Tank Contents Known] --> B[Gas Testing]
    B --> C{Gas Type?}
   

IS 9964 Part 1: Key Points on Opening Tank & Sludge Removal

1. Sludge Removal Methods (Clause 15.2)

• Sweep sludge into piles → shovel into buckets/wheelbarrows.
• Wash tank with water hose; keep water velocity ≤ 1 m/s.
• Use floor-level clean-out manways for flushing sludge-laden water.
• If no manways, use self-priming pumps or water-operated ejectors.

2. Sludge Disposal (Clause 15.2.2)

• Discharge sludge-laden water into a sludge pit near the tank.
• Size pit based on sludge volume.
• Sludge settles; water drains to sewer with extra downstream water to dilute hydrocarbons.
• Use steam/air pumps to drain excess water from pit.

3. Safety for Personnel (Clause 15.1 & 15.2.2)

• Tank must be vapour-freed before opening.
• Entry conditions:
  • Lower Flammable Limit (LFL) < 20%
  • Oxygen content > 19.5%
• Personnel protective gear:
  • Fresh air hose mask, gloves, rubber boots, light-colored overalls.
• Rotate men periodically.

4. Checklist for Safe Entry (Clause 17.1)

• Refer Appendix A for detailed safety checklist before entry.

Summary Table: Sludge Removal Parameters

flowchart TD
    A[Tank Vapour-free] --> B[Open Tank]
    B --> C{Sludge Removal Method}
    C -->|Manways present| D[Flush with water]
    C -->|No manways| E[Use pumps/ejectors]
    D --> F[Discharge sludge water to pit]
    E --> F
    F --> G[Sludge settles in pit]
    G --> H[Water drains to sewer with dilution]
    B --> I[Personnel enter with PPE &

IS 9964 Part 1: Surface Preparation and Painting of Storage Tanks

Key Specifications (Clause 16.1.2)

• Surface Preparation:
  • Clean by shot blasting to remove rust, scale, and contaminants completely.
• Painting Sequence:
  1. Apply 1 coat of amine cured epoxy resin clear lacquer immediately after blasting.
  2. Apply 3 coats of amine cured epoxy resin paint.
  3. Finish with 1 coat of clear lacquer (5th coat overall).
• Dry Film Thickness (DFT):
  • Minimum total DFT = 125 microns.

Maintenance Painting (Clause 16.2)

• Avoid scratching painted surfaces during sludge removal.
• Visual inspection after cleaning:
  • If deteriorated area ≤ 25% → patch painting with 3 coats of epoxy paint.
  • If > 25% → complete repainting required.

Lead Hazard Treatment (Clause 6.2.4)

• Remove lead hazard by:
  i) Shot blasting to bare metal, or
  ii) Heating tank to cherry-red heat to destroy organic lead.

Summary Table: Painting Coats & Thickness

flowchart LR
    A[Shot Blasting] --> B[1st Coat: Clear Lacquer]
    B --> C[3 Coats: Epoxy Resin Paint]
    C --> D[5th Coat: Clear Lacquer]
    D --> E[Total DFT ≥ 125 microns]

This ensures corrosion protection and safe tank operation per IS 9964 Part 1.

IS 9964 Part 1: Checklist for Tank Cleaning and Entry

Key Points from Clause 17.1 & Related Clauses:

• Appendix A (IS 9964 Part 1) provides a detailed checklist to ensure tank safety before personnel entry for cleaning, inspection, or repair.

• Major steps for tank cleaning (Clause 9.1):

  1. Preliminary preparations:
     • External tank inspection
     • Surrounding area survey
     • Crew training and equipment inspection
  2. Control ignition sources to prevent fire/explosion.
  3. Empty tank by pumping and floating; blank-off after oil removal.
  4. Vapour-free the tank to ensure safe atmosphere.
  5. Test for hydrocarbon vapour and toxic gases using gas detectors.
  6. Open tank and remove sludge safely.

• Hazards to consider (Clause 8.1):

  • Slipping, falling objects
  • Falling from or through tank roof
  • Improper scaffolding

Typical Checklist Items (Summary):

Safety Formula for Vapour Testing:

• Lower Explosive Limit (LEL) Safety Margin: Entry only if hydrocarbon vapour < 10% LEL.

flowchart TD
    A[Preliminary Prep] --> B[Control Ignition]
    B --> C[Empty Tank]
    C --> D[Vapour-Free Tank]
    D --> E[Test Atmosphere]
    E --> F[Safe Entry & Cleaning]

Summary: Follow Appendix A checklist strictly; ensure vapour concentration is below 10

IS 9964 Part 1: Sludge Disposal Key Points & Specifications

1. Weathering Method (Clause 18.2.2):

• Spread sludge in 50 mm thick even layers in a pit.
• Expose to sunny weather for 4 to 8 weeks.
• Mix sludge with sand/earth in 1:1 ratio to reduce total lead < 0.5%.
• Bury sludge-earth mix with 600 mm earth cover.
• Mark burial site permanently with a signboard.

2. Burying Method (Clause 18.2.1):

• Dig a pit and dump sludge.
• Cover with 300 to 600 mm fresh earth.
• Mark the area to prevent accidental disturbance.
• Organic lead compounds decompose slowly; protective clothing recommended if disturbed.

3. Discharge Restrictions (Clause 15.2.1):

• Sludge from leaded tanks must not be discharged into sewers.
• Follow prescribed disposal methods (weathering or burying).

Summary Table:

flowchart LR
    A[Sludge from Leaded Tank] --> B{Disposal Method}
    B -->|Weathering| C[Spread 50mm layer]
    C --> D[Expose 4-8 weeks]
    D --> E[Mix 1:1 with sand/earth]
    E --> F[Bury with 600mm earth cover]
    B -->|Burying| G[Dig pit]
    G --> H[Dump sludge]
    H --> I[Cover with 300-600mm earth]
    I --> J[Mark site permanently]

Note: Always follow safety precautions during sludge handling and disposal.

IS 9964 Part 1 - Key Points on Dismantling and Disposal of Tanks

1. Procedure Reference

• Follow Clauses 19.2 to 19.8 for detailed dismantling and disposal steps.
• Checklist for safe entry & inspection: Appendix A (Clause 17.1).

2. Sludge Disposal (Clause 18.2.2.1)

• If organic lead ≤ 20 ppm (0.002 wt%) after weathering, sludge can be treated as non-toxic industrial waste.
• Then, remove signs and fences safely.

3. Dismantling Precautions (Clause 19.4)

• Dismantling causes dust from scale and rust, especially during cold-cutting or sandblasting.
• To reduce dust, use water spray or fog.
• Prefer dismantling from outside to minimize dust exposure.

Summary Table for Sludge Lead Content:

Safety Flowchart for Tank Dismantling

flowchart TD
    A[Check tank safety (Appendix A)] --> B{Sludge Lead ≤ 20 ppm?}
    B -- Yes --> C[Treat sludge as non-toxic waste]
    B -- No --> D[Follow hazardous sludge disposal]
    C --> E[Remove signs/fences]
    E --> F[Dismantle tank from outside]
    F --> G[Control dust with water spray/fog]
    D --> G

Note: Always comply with local environmental and safety regulations beyond IS 9964.