Safety code for dress divers in civil engineering works

IS 10291: Scope & Key Specifications for Diving Operations in Civil Engineering

Scope:

• Applicable for diving operations up to 60 m depth in civil engineering works (Clause 2.1).
• Focused on safety measures to minimize accidents and improve efficiency (Clause 0.3).
• Based on international standards and practices, including UK Ministry of Defence diving manual (Clause 0.4).

Key Tables and Formulas:

1. Duration of Dive & Decompression Time (Clause 6.2):

2. Decompression Arrangements (Clause 6.1):

• For depths > 10 m, decompression must be provided at site (water or medical lock).
• For depths ≤ 35 m, follow IS 4138-1977 decompression tables.
• For depths > 35 m, add 5 minutes to decompression time from the table above.

Additional Notes:

• Values should be rounded per IS 2-1960 rounding rules.
• Safety code references:

Qualifications of Divers (IS 10291 - Clause 2.1 & 2.1.1)

Mandatory criteria for divers:

• Age: ≥ 18 years.
• Medical fitness: Certified fit by a qualified medical practitioner within the last 6 months.
  • Chest and bone radiographs every 12 months.
• Pressure test: Successfully tested to max working pressure in water or compression chamber.
• Knowledge: Thorough understanding of diving signals (see Appendix A).
• Helmet divers: Must demonstrate competence in:
  • Ladder entry and 5-minute hold without air interruption.
  • Descending, circular search in zero visibility and ≥ 0.6 m mud/silt.
  • Working on underwater suspended platform.

Key Table: Duration of Dive & Decompression Time (Clause 6.2)

Notes on Rounding (Clause 0.5)

• Use IS:2-1960 for rounding off numerical values.
• Retain the same number of significant digits as the specified value.

flowchart TD
    A[Start:

IS 10291: Diving Operations & Safety Measures — Key Points

Depth & Duration Limits (Clause 2.1, 6.2)

• Diving depth limited to 60 m for civil engineering.
• Up to 18 m: No limit on dive duration.
• Beyond 18 m, max dive duration and decompression times are specified:

Decompression Procedures (Clause 6.1)

• Decompression must be done in water or medical lock.
• For depths >10 m, decompression facilities are mandatory onsite.
• Use IS 4138-1977 decompression tables for depths ≤35 m.
• For depths >35 m, add 5 minutes to decompression time from the above table.

Additional Safety Measures

• Follow Safety Code for Working in Compressed Air (First revision).
• Round off values per IS 2-1960 for compliance.
• Adherence reduces accidents and improves efficiency.

flowchart TD
    A[Dive Depth ≤ 18m] --> B[No Duration Limit]
    A --> C{Depth > 18m}

Key Specifications from IS 10291: Diving Equipment and Maintenance

1. Air Supply Requirements (Clause 5.2)

• Normal air supply: 45 litres/min per diver
• Hard work air supply: 75 litres/min per diver
• Total air output: Multiply diver's air requirement by absolute pressure (bars)
  [ \text{Air output} = \text{Air supply} \times \text{Absolute pressure} ]
• Example: At 30 m depth (4 bars absolute), hard work requires
  [ 75 \times 4 = 300 \text{ litres/min} ]

2. Decompression Table (Clause 6.2)

3. Altitude Diving Adjustments (Clause 3.4)

• Adjust depth for decompression schedules as surface pressure < 1 bar:
  • 100–300 m altitude: Add 25% to depth
  • 300–2000 m: Add 30%
  • 2000–3000 m: Add 50%
  • Up to 100 m: No

IS 10291 Key Points on Supply of Air for Diving

1. Air Requirement (Clause 5.2)

• Normal work: Minimum air supply = 45 litres/min
• Hard work: Air supply may increase to 75 litres/min
• Total air output = Diver's air requirement × Absolute pressure (bars)

Example:
At 30 m depth (4 bars absolute), hard work air supply =
75 L/min × 4 bars = 300 litres/min

2. Air Quality & Equipment (Clause 5.1)

• Air must be fit for respiration and supplied at pressure suitable for depth
• Compressors and cylinders must be well-maintained and dedicated for breathing air
• Avoid using industrial compressors or hoses previously used for industrial air due to contamination risk

3. Airpipe Specifications (Clause 4.2)

• Airpipe must withstand intended pressure with a factor of safety ≥ 2
• Materials must be suitable and approved for breathing air use

Summary Table: Air Supply Calculation

flowchart LR
    Diver[Air Requirement] -->|× Absolute Pressure| Compressor[Compressor Output]
    Compressor -->|Supply Air| Diver
    Compressor -->|Maintenance & Filters| Quality[Air Quality]
    Airpipe -->|Withstand Pressure × 2| Compressor

Note: Always ensure compressor capacity matches calculated total air output for safety and efficiency.

IS 10291 - Decompression Procedures Summary

Key Points from Clauses 6.1 & 6.2:

• Decompression must be done underwater or in a surface medical lock.
• For depths > 10 m, decompression arrangements are mandatory.
• Use IS 4138-1977 decompression tables for depths up to 35 m.
• For depths > 35 m, add 5 minutes to decompression time from table values.

Decompression Time Table (Clause 6.2):

Altitude Diving Adjustments (Clause 3.4):

Adjust dive depth for reduced surface pressure:

IS 10291: Emergency and Standby Arrangements - Key Points

1. Decompression Arrangements (Clause 6.1 & 6.2)

• Decompression required for depths > 10 m, either in water or in a medical lock on surface.
• Use decompression tables from IS:4138-1977 for depths ≤ 35 m.
• For depths > 35 m, add 5 minutes to decompression time from the table.
• Maximum dive duration and decompression times are as follows:

2. Standard Line Signals (Appendix A, Clause 3.1)

• A stout long line is used for communication between diver and attendant.
• Signals by line pulls:

IS 10291 - Standard Line Signals (Clause 3.1 & Appendix A)

Key Specifications:

• Line arrangement:

  • Stout long line laid over right shoulder (from rear) and under left arm.
  • End secured round belt at back, allowing user to be pulled out in emergencies.

• Signaller requirements (Clause 2.4):

  • Medically fit, mentally alert.
  • Certified in first aid and artificial respiration.

Standard Line Signals (Table 1)

Notes:

• Signals must be repeated from both ends to confirm understanding and action.
• Clear communication is critical for safety during lowering or pulling operations.

flowchart LR
    User["User"] -- "Line Pulls" --> Attendant["Attendant"]
    Attendant -- "Line Pulls" --> User
    subgraph Signal Types
        A1["1 Pull: OK / Stop"]
        A2["2 Pulls: Lower More"]
        A3["3 Pulls: Pull Up"]
        A4["Succession: Danger"]
    end
    User --> A1
    User --> A2
    User --> A3
    User --> A4
    Attendant --> A1
    Attendant --> A2
    Attendant --> A3
    Attendant --> A4

This system ensures safe, reliable communication during rescue or lowering operations as per IS 10291.