IS 102 : Safety Engineering – I SBTET AP IS

2.1 MACHINE OPERATION AND GUARDING

Principles in Machine Guarding

Machine guarding aims to protect workers from injuries due to moving parts of machinery.

Basic Principles:

1. Prevent contact between the operator and hazardous moving parts.

2. Ensure guards do not interfere with normal operation.

3. Prevent accidental removal or bypassing of guards.

4. Create minimal obstruction for maintenance.

5. Guards must be durable, smooth, and corrosion-resistant.

Ergonomics of Machine Guarding

• Guards should be designed considering operator height, reach, posture, and visibility.

• Controls must be within comfortable reach.

• Avoid awkward postures or repetitive motion that cause fatigue or musculoskeletal issues.

• Emergency stop switches should be easily accessible.

Types of Machine Guards

1. Fixed Guards: Permanent parts of machine — simple, reliable, inexpensive.
   Example: Cover on gears or pulleys.

2. Interlocked Guards: Machine stops when guard is opened or removed.

3. Adjustable Guards: Can be adjusted to suit different operations or material sizes.

4. Self-adjusting Guards: Automatically move according to material thickness.

5. Distance or Barrier Guards: Maintain safe distance between worker and hazard (e.g., fencing).

6. Presence-sensing Devices: Use light curtains, sensors, or pressure mats to stop operation if someone enters danger zone.

Design and Selection of Guards

• Should meet statutory standards (BIS, OSHA).

• Must be strong enough to withstand impact.

• Avoid sharp edges.

• Easy to clean and maintain.

• Transparent material preferred where visibility is needed.

Guarding of Different Machinery

Type of Machine	Hazard	Safety Precautions / Guards
Wood Working	Flying chips, dust, rotating blades	Enclosure guards, suction for dust, eye protection
Paper Machinery	Nip points, rotating rolls	Fixed guards, automatic feed, emergency stops
Rubber Machinery	In-running nips, hot surfaces	Trip guards, safety trip rods, heat shields
Printing Machinery	Roller traps, ink hazards	Interlocked guards, auto-stop, gloves, ventilation
Machine Tools (Lathe, Drilling, etc.)	Entanglement, flying swarf	Chuck guards, tool rests, proper PPE

Built-in Safety Devices

• Emergency stop buttons (E-stop)

• Two-hand control devices

• Automatic feed and ejection systems

• Overload and over-speed protection

• Foot or hand controls with safety interlock

Maintenance and Repairs

• Guards must be inspected and maintained regularly.

• Replace damaged or missing guards immediately.

• Lockout–Tagout (LOTO) system must be followed before maintenance.

• Periodic training on safe maintenance practices.

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2.2 SAFETY IN THE USE OF MACHINES

2.2.1 Safety in the Use of Specific Machines

Machine Type	Hazards	Safety Measures
Power Press	Hand injury, ejection of workpiece	Two-hand control, interlocked guard, light curtain, regular inspection
Shearing Machine	Finger amputation, flying scraps	Fixed guard, foot pedal with shield, hold-downs
Bending Machine	Crushing between die and plate	Interlock guard, foot switch cover
Rolling Machine	In-running nip between rolls	Trip bars, emergency stop rope
Drawing Machine	Material whipping, entanglement	Guarded reels, slow-speed start, proper PPE
Turning (Lathe)	Entanglement with rotating chuck	Chuck guard, remove loose clothing, use proper tool rest
Boring Machine	Flying chips, rotating tools	Safety shield, goggles, chip guard
Milling / Shaping	Flying metal, cutter contact	Adjustable guards, secure clamping, cutter shield
Planning / Broaching	Tool breakage, moving table	Limit switch, guard on moving table
Grinding Machine	Wheel burst, eye injury	Wheel speed check, tool rest ≤3 mm, wheel guard, eye shield
CNC Machines	Program errors, tool crash	Fully enclosed guards, interlocked door, emergency stop

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2.2.2 Selection and Care of Cutting Tools

• Select tool according to job material and cutting conditions.

• Maintain correct tool geometry and sharpness.

• Avoid using cracked or damaged tools.

• Ensure proper clamping and alignment.

• Store tools in dry, safe conditions to prevent rust or damage.

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2.2.3 Preventive Maintenance and Periodic Checks

• Preventive maintenance = Regular servicing before failure occurs.

• Reduces breakdowns, ensures safe and smooth operation.

• Checks include:

  • Lubrication and cleaning.

  • Checking guards, interlocks, and emergency stops.

  • Inspection of belts, gears, and bearings.

  • Calibration of safety sensors and limit switches.

• Maintain maintenance logbook.

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2.2.4 Associated Hazards and Their Prevention

Common Hazards:

• Entanglement, cutting, crushing, ejection, noise, vibration, electric shock.

Prevention:

• Proper guarding and PPE.

• Safe operating procedures (SOPs).

• Adequate lighting and housekeeping.

• Operator training and supervision.

• Strict adherence to Lockout–Tagout system during maintenance.

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2.3 MATERIAL HANDLING AND STORAGE OF MATERIALS

2.3.1 Manual Material Handling

Kinetics of Manual Handling:

• Involves human effort to lift, push, carry, or pull objects.

• Poor posture or overexertion can cause back injuries.

Maximum Load Limits:

• Men: ~55 kg

• Women: ~20 kg (as per Indian Factories Rules)

• Avoid lifting beyond capability; use team lifting or mechanical aids.

Safe Lifting Techniques:

1. Assess load and plan lift.

2. Keep back straight, bend knees.

3. Hold load close to body.

4. Avoid twisting while lifting.

5. Use correct footwear and gloves.

Handling Objects of Different Shapes:

• Use tongs, clamps, or straps for irregular items.

• Use padding for sharp edges.

Safe Use of Accessories:

• Slings, ropes, hooks, and chains must be inspected before use.

• Do not exceed safe working load (SWL).

• Use color coding or tagging for identification.

Storage Safety:

• Stack material on firm, level ground.

• Do not exceed floor loading limits.

• Provide adequate aisle space for movement.

• Heavy materials at bottom, lighter on top.

• Follow FIFO (First In – First Out) principle.

Ergonomics in Handling and Storage:

• Design layout to minimize bending, stretching, or carrying long distances.

• Use adjustable platforms and mechanical aids.

• Ensure proper lighting and ventilation.

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2.3.2 Mechanical Material Handling

Lifting Machinery, Lifts, and Hoists

• Must be designed and constructed as per BIS/ILO standards.

• Fitted with:

  • Overload indicators

  • Limit switches

  • Emergency brakes

  • Guarded moving parts

Safety Aspects:

• Load must not exceed SWL.

• Proper signaling system (hand signals or radio communication).

• Regular inspection by competent person.

• Maintain test certificates and records.

Industrial Trucks (Forklifts, etc.)

• Operator must be trained and licensed.

• Avoid overloading or uneven loading.

• Maintain clear visibility.

• Avoid sharp turns or slopes at speed.

• Daily pre-use inspection (brakes, horn, lights, tires).

Conveyors

• Provide emergency pull-cords along the length.

• Guards on all nip points and moving parts.

• Regular lubrication and inspection.

• No riding on conveyors.

Lifting Tackles and Loose Gears

• Hooks, chains, ropes, and slings must be tested periodically.

• Tag with safe working load and identification number.

• Replace damaged parts immediately.

Safe Working Load (SWL):

• Maximum load a lifting device can safely handle.

• Must be clearly marked and never exceeded.

Competent Person (as per Safety Legislation):

• Person with adequate knowledge and experience to inspect and certify lifting equipment.

• Responsible for:

  • Periodic examination and testing.

  • Maintaining inspection records.

  • Ensuring compliance with Factories Act and Indian Standards.

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2.4 WORKING AT HEIGHTS

2.4.1 Working at Heights

Definition:
Any work performed at a place where a person could fall and cause personal injury (generally 2 m or more above ground level).

Incidence of Accidents

• Falls from ladders, scaffolds, roofs, or unguarded edges are among the leading causes of fatalities in construction and maintenance industries.

• Major causes include:

  • Unsecured or defective ladders/scaffolds

  • Poor edge protection

  • Lack of harness or anchorage

  • Slippery or unstable surfaces

  • Improper supervision

Safety Features in Design, Construction, and Use

Equipment / Area	Safety Features / Requirements
Stairways	Uniform riser height; anti-slip treads; handrails on both sides; proper lighting; regular cleaning.
Ramps	Non-slip surface; slope < 1:10; edge protection or guardrails; adequate width.
Working Platforms / Scaffolds	Stable base; guardrails (1 m height); mid-rails and toe boards; planking properly secured; inspection before use.
Gangways / Walkways	Minimum width 600 mm; guardrails on open sides; no obstructions; safe access and egress.
Ladders (Fixed & Portable)	Correct angle (4:1); secured at top and bottom; extend ≥ 1 m above landing; inspected regularly; only one person at a time.
Roof Work	Use safety harness and lifelines; roof edge protection; crawl boards on fragile roofs; warning signage.

Other Safety Requirements While Working at Heights

• Conduct risk assessment before starting work.

• Workers must be trained and medically fit.

• Use full-body harness with double lanyard.

• Anchor points must withstand ≥ 15 kN load.

• Tools secured with lanyards to prevent falling objects.

• Use barricades and signage below work area.

• Implement rescue and emergency plan.

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2.4.2 Working in Confined Spaces

Definition:
A space with limited entry/exit, poor ventilation, and potential for hazardous atmosphere (e.g., tanks, manholes, silos).

Hazards:

• Oxygen deficiency or enrichment

• Toxic gases (H₂S, CO, etc.)

• Fire/explosion risk

• Engulfment or entrapment

• Heat stress or poor visibility

Safety Precautions:

1. Obtain Confined Space Entry Permit.

2. Test atmosphere for O₂, flammable gases, and toxicity.

3. Provide forced ventilation and lighting.

4. Use intrinsically safe electrical tools.

5. Keep standby person and communication system.

6. Use harness and lifeline for workers.

7. Keep rescue and first-aid arrangements ready.

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2.4.3 Working Underground

Examples: Tunnels, trenches, pipelines, cable ducts.

Hazards:

• Cave-ins or collapse

• Oxygen deficiency

• Flooding or seepage

• Falling objects

• Electrical hazards

Safety Measures:

• Proper shoring, sloping, or benching of trenches.

• Adequate lighting and ventilation.

• Gas testing before entry.

• Use helmets, boots, and respiratory protection.

• Emergency escape routes and alarm systems.

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2.5 HAND TOOLS AND PORTABLE TOOLS

Main Causes of Tool Accidents

• Use of defective, worn-out, or wrong tools.

• Improper handling or carrying.

• Lack of inspection and maintenance.

• Working without PPE.

• Tools lying scattered causing trip hazards.

Control of Tool Accidents

• Provide proper storage and issue system.

• Regular inspection and maintenance.

• Training for correct tool use.

• Replace damaged or mushroom-headed tools.

• Enforce PPE: gloves, goggles, and safety shoes.

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Centralized and Personal Tool Issue System

• Centralized Tool Room: All tools stored, inspected, and issued by responsible person.

• Personal Issue System: Each worker provided with personal set of tools, reducing misuse.

• Record issue and return to track maintenance and life span.

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Purchase, Storage, and Supply of Tools

• Purchase only BIS/ISO-certified tools.

• Store in dry, organized racks with identification.

• Maintain inventory records and inspection tags.

• Supply tools only after inspection and sharpening.

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Inspection, Maintenance, and Repair

• Regular checks for cracks, wear, loose handles, or burrs.

• Sharpen cutting edges; replace damaged handles.

• Keep tools clean and lubricated.

• Use tempering and dressing for metal-working tools.

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Detectable Causes of Tool Failures

• Overloading or misuse.

• Poor material quality.

• Improper tempering or heat treatment.

• Corrosion or fatigue.

• Inadequate inspection.

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Tempering, Safe Ending, and Dressing

• Tempering: Heat treatment to increase toughness of tool steel.

• Safe Ending: Smooth edges and corners to prevent cuts.

• Dressing: Grinding or shaping cutting edges to maintain correct angle.

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Types of Tools

1. Metal-Cutting Tools: Chisels, hacksaws — keep edges sharp, use with goggles.

2. Wood-Cutting Tools: Axes, saws — use dry handles and firm grip.

3. Miscellaneous Cutting Tools: Knives, blades — store safely after use.

4. Torsion Tools: Screwdrivers, spanners — avoid over-torquing.

5. Shock Tools: Hammers — use proper weight and condition.

6. Non-Sparking Tools: Made of bronze or brass for use in flammable areas.

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Portable Power Tools

Examples: Drills, grinders, sanders, saws.

Safety Measures:

• Select correct tool for task and voltage.

• Check cords, plugs, and insulation before use.

• Ensure double insulation or earthing.

• Avoid using in wet conditions.

• Keep guards in place.

• Disconnect from power before changing bits or discs.

• Regular inspection and preventive maintenance.

• Store safely after use.

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2.6 PLANT DESIGN AND HOUSEKEEPING

Plant Layout and Safe Distance

• Layout should allow safe workflow and material movement.

• Maintain minimum clearances between machines.

• Emergency exits and escape routes must be accessible.

• Provide proper lighting, ventilation, and noise control.

• Segregate hazardous processes from normal operations.

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Need for Planning and Follow-up

• Safety must be integrated from the design stage.

• Conduct risk assessments and safety audits periodically.

• Update layouts when new machines or processes are introduced.

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Safety and Good Housekeeping

Definition:
Systematic management of workplace cleanliness, orderliness, and maintenance to prevent accidents.

Typical Accidents Due to Poor Housekeeping:

• Slips, trips, and falls

• Fire due to accumulation of waste

• Obstructed emergency exits

• Mechanical damage to equipment

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Disposal of Scrap and Waste

• Provide metal bins and segregation system.

• Dispose hazardous waste as per Pollution Control Board norms.

• Avoid accumulation of oily rags or combustible waste.

• Follow “Clean as You Go” policy.

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Prevention of Spillage

• Use drip trays and absorbents.

• Check hoses and valves for leaks.

• Provide bund walls around tanks.

• Clean spills immediately and safely.

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Marking of Aisles and Work Areas

• Mark pathways, fire exits, and loading zones with paint or floor tape.

• Use arrows for traffic direction.

• Keep minimum width of 1 m for aisles.

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Use of Color as Aid for Housekeeping

Color	Meaning / Use
Red	Fire equipment / Emergency stop
Yellow	Caution / Physical hazards
Green	Safety equipment / First aid
Blue	Mandatory signs (PPE, etc.)
White/Black Stripes	Traffic and housekeeping markings

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Housekeeping Contests & Inspections

• Promote cleanliness through competitions and reward programs.

• Conduct routine inspections with checklists for each area.

• Assign cleaning duties and rotate responsibilities among staff.

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Cleaning Methods

• Dry sweeping or vacuuming (avoid blowing).

• Wet mopping in non-slip areas.

• Use mechanized sweepers for large spaces.

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Employee Assignment & Checklists

• Each department responsible for its housekeeping.

• Use checklists to ensure daily compliance (floors, aisles, lighting, storage, waste bins).

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Benefits of Good Housekeeping

• Reduces accidents and fire risk.

• Improves morale and productivity.

• Enhances company image and compliance.

• Facilitates quick emergency evacuation.

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Role of Preventive Maintenance

• Regular servicing avoids leakage, vibration, or breakdowns.

• Ensures safe and efficient plant operation.

• Extends equipment life and reduces downtime.

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Importance of Standards and Codes of Practice

• Follow BIS, OSHA, and ISO guidelines for plant and equipment design.

• Regular audits ensure compliance.

• Adopting best practices leads to safe, clean, and productive workplaces.

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2.7 INDUSTRIAL LIGHTING & ILLUMINATION

2.7.1 Purpose and Benefits of Lighting

• Ensures safe and efficient working conditions.

• Reduces eye strain, fatigue, and accidents.

• Improves work quality and accuracy.

• Enhances morale and workplace appearance.

2.7.2 Phenomenon of Lighting and Safety

• Adequate illumination prevents misjudgment of hazards.

• Poor lighting leads to slips, trips, falls, and operational errors.

2.7.3 Sources and Types of Artificial Lighting

• Sources: Incandescent, fluorescent, mercury vapor, LED.

• Types: General, task, and emergency lighting systems.

2.7.4 Principles of Good Illumination

• Uniform distribution of light.

• Suitable intensity without glare or shadow.

• Correct color rendering.

• Maintenance of clean fixtures and reflectors.

2.7.5 Standards and Design

• Recommended illumination levels as per BIS and Factory Act standards.

• Design considerations: height of fitting, reflection, contrast, and task type.

• Use of color coding for improved visibility and hazard identification.

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2.8 VENTILATION AND HEAT STRESS

2.8.1 Purpose of Ventilation

• To provide fresh air and remove heat, fumes, dust, and contaminants.

• Maintains temperature and humidity within comfort limits.

2.8.2 Physiology of Heat Regulation

• Human body maintains balance through sweating, convection, radiation, and evaporation.

2.8.3 Thermal Environment and Measurement

• Measured using Dry Bulb, Wet Bulb, and Globe Thermometers (WBGT index).

• Thermal comfort achieved when air temperature, humidity, and airflow are within safe limits.

2.8.4 Heat Stress and Its Control

• Effects: Fatigue, dehydration, heat exhaustion, and heat stroke.

• Control Measures:

  • Source control (insulation, shielding).

  • Dilution ventilation and exhaust systems.

  • Use of fans, coolers, and air conditioning.

  • Work-rest cycles and hydration.

2.8.5 Standards and Codes

• IS 3103:1975 – Code of Practice for Industrial Ventilation.

• National Building Code, Part VIII – Building Services.

• Factories Act, 1948 – Specifies minimum air changes and ventilation rates.

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2.9 NOISE AND VIBRATION

2.9.1 Noise

• Types: Continuous and Impulse Noise.

• Effects on Humans: Hearing loss, fatigue, reduced concentration, communication difficulty.

2.9.2 Measurement and Evaluation

• Measured in decibels (dB) using Sound Level Meter.

• Permissible Exposure Limits (PEL): As per OSHA and BIS standards (e.g., 90 dB for 8 hours).

2.9.3 Noise Control Measures

• At Source: Use of silencers, mufflers, acoustic enclosures.

• Along Path: Sound barriers, insulation, absorption materials.

• At Receiver: Use of ear muffs, ear plugs, administrative controls.

2.9.4 Vibration

• Sources: Machines, compressors, hammers, vehicles.

• Effects: Fatigue, bone/joint problems, damage to equipment.

• Measurement: Using vibration meters (acceleration, velocity, displacement).

• Control: Vibration damping, balancing, isolation, and regular maintenance.
  

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2.10 ELECTRICAL HAZARDS

2.10.1 Hazards of Electrical Energy

• Common Hazards: Electric shock, burns, fire, explosion, arc flash.

• Safe Limits:

  • Current above 10 mA may cause muscle contraction.

  • 50 mA or more can be fatal.

• Voltage Limits: Low voltage (<50V) is generally considered safe under dry conditions.

• Safe Distance from Lines: Maintain minimum approach distances as per IS 5216 and IE Rules.

• Protection of Conductors:

  • Use appropriate cable insulation and correct current rating.

  • Avoid overloading and improper joints.

• Power Isolation:

  • Install proper switches and circuit breakers.

  • Provide lockout-tagout (LOTO) during maintenance.

• Protection Devices:

  • Overload Protection: Fuses, thermal relays.

  • Short Circuit Protection: Circuit breakers.

  • Earth Fault Protection: Residual current devices (RCD).

  • Surge Protection: Lightning arrestors, surge suppressors.

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2.10.2 Precautions and Protection Measures

• Borrowed Neutrals: May cause potential differences leading to shock; always use dedicated neutral wires.

• Portable Electrical Tools:

  • Use double-insulated tools.

  • Inspect cords and plugs before use.

  • Keep equipment dry and clean.

• Protection in Hazardous Atmospheres:

  • Use flameproof or intrinsically safe electrical fittings.

  • Follow electrical area classification:

    • Zone 0: Continuous presence of explosive gas.

    • Zone 1: Occasional presence.

    • Zone 2: Rare presence.

  • Equipment must be certified as per IS/IEC 60079 series.

• Maintenance:

  • Periodic insulation resistance testing.

  • Proper earthing, labeling, and circuit identification.

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2.11 STATIC ELECTRICITY

2.11.1 Basics and Causes

• Static Electricity: Electric charge produced by friction or separation of materials.

• Electrostatic Charging: Occurs during movement of non-conductors like rubber, plastic, and textiles.

• Common Situations:

  • Flow of liquids through pipes.

  • Belt drives, conveyors, pneumatic transport.

2.11.2 Hazards and Control

• Hazards:

  • Sparks may ignite flammable vapors or dust.

  • Damage to sensitive electronic equipment.

• Control Measures:

  • Earthing and Bonding: Connect conductive parts to earth to discharge static.

  • Humidification: Maintain relative humidity to reduce charge build-up.

  • Use of Antistatic Additives and Materials.

• Recommended Earthing Resistance:

  • Should not exceed 1 ohm for static control systems.

  • Follow IS 3043 – Code of Practice for Earthing.

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2.12 LIGHTNING ARRESTORS

2.12.1 Fundamentals

• Lightning: A natural discharge of static electricity between cloud and earth or between clouds.

• Lightning Stroke: Direct hit to a structure causing high current and heat.

• Lightning Flash: Visible discharge path during stroke.

2.12.2 Protection System

• Purpose: Diverts high voltage discharge safely to earth, preventing structural damage or fire.

• Components:

  • Air Terminals (Lightning Rods).

  • Down Conductors.

  • Earth Electrodes (Earth Terminals).

• Design Considerations:

  • Use copper/aluminum conductors with adequate cross-section.

  • Maintain low resistance path to ground.

  • Earth resistance should be below 5 ohms.

• Installation Locations:

  • High-rise buildings, chimneys, tanks, storage areas, power stations.

• Reference Standard: IS 2309 – Code of Practice for the Protection of Buildings and Allied Structures Against Lightning.

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2.13 SAFETY CHECKLIST FOR BUYING NEW MACHINERY

2.13.1 Pre-Purchase Evaluation

• Verify compliance with BIS/OSHA/IEC safety standards.

• Ensure manufacturer provides test certificates and conformity reports.

• Check for CE or ISI marking for electrical and mechanical safety.

2.13.2 Design and Operational Safety

• Adequate machine guarding and emergency stop buttons.

• Presence of interlocks and fail-safe features.

• Noise, vibration, and emission levels within permissible limits.

• Safe location for maintenance and cleaning access.

2.13.3 Documentation and Training

• Machine manuals, drawings, and risk assessment reports available.

• Vendor must provide installation and operational training.

2.13.4 Inspection Before Purchase

• Conduct a safety audit checklist, including:

  • Stability and anchoring.

  • Electrical safety compliance.

  • Guarding of moving parts.

  • Provision for emergency controls.

  • Clear labeling and hazard warnings.