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Safety Interview Questions 7 contains about confined space & Confined Space Hazards, H2S safety, fire extinguisher,

61. Enlist precaution to be taken prior to taken to and during excavation work? OR What is the safety precautions required for a safe excavation?
62. What is confined space?
63. What are the Confined Space Hazards? 
64. What is the procedure for entering a confined space hazards? OR What are the important PRECAUTIONS for confined space? 64. What is the procedure for entering a confined space hazards? OR What are the important PRECAUTIONS for confined space? 
65. What you know about working in a confined space entry? OR Explain about confined space entry? 
66. Explain H2S? OR What is H2S and its characteristics explain?
67. What are prominent H2S HAZARDS? 
68. Explain the precautionary measures to be taken while approaching H2S prone area? 
69. How to treatment of persons affected by H2S? 
70. Which type of fire extinguisher is used for each class of fire? TYPES OF EXTINGUISHERS & THEIR USE: (As Per KOC)

61. Enlist precaution to be taken prior to taken to and during excavation work? OR What is the safety precautions required for a safe excavation?

 No excavation work in KOC area without clearance of Explosive Ordinance Disposal (EOD).

 No mechanical excavation closer than 5 meters to any hydrocarbon carrying pipeline.

 No mechanical excavation closer than 3 meter to a non-hydrocarbon carrying pipeline, cables and services.

 For any excavation deeper than 1m, ladder must be positioned projecting minimum 1 meter above the edge of the excavations.

 Ladders shall be provided every 7.5 meters (25 feet) of lateral travel in the trench.

 Ladders shall be securely supported at the bottom as well as at the top.

 Excavated material shall be placed 1m from the edge of the excavation for depth up to 1.2 meter.

(Accordingly placement of excavated material shall be increased proportion to the depth of excavation.)

 Heavy equipment, machinery shall be kept at least 3 meters away from the edge.

 Any walkway across trench shall have scaffold type platform with handrails.

 All trenches shall have barrier (such as fixed guardrails) and reflective warning notices clearly displayed. Flashing lights are mandatory during poor visibility.

 The access to plant, equipment and emergency services must not be obstructed by the trenches.

 No mechanical excavation is allowed inside the existing KOC facilities (Gathering Center, Booster Station, water injection and handling facilities, etc.)


62. What is confined space?

 Any enclosure having a limited means of entry & exit and it is not designed for continuous occupancy.

 There will be a presence of any hazardous substances such as flammable and toxic gases, oxygen deficiency, hot or humid atmosphere or any combination of it.

Examples: Process vessels, Tanks, Bins, Stacks, Large pipe, Duct, Pits & Trench etc. Any excavation with depth more than 1.2 meter.


63. What are the Confined Space Hazards? 

A confined space may have one or combination of the following hazards:

 Oxygen deficiency

 Presence of flammable, combustible or pyrophoric materials (HC, Sludge etc.)

 Presence of toxic gases, corrosive or hazardous materials (H2S, Co, NH3 etc.)

 Poor illumination, Ventilation & Communication.

 High temperature and humidity.

 Limited entry & exit / Restricted access.

 Restricted movement inside.

 Falling / Tripping hazards

 Presence of reactive or self-igniting material.

 Hazard due to electricity or moving machinery.

 Hazard due to pressurized fluid.

 Hazard due to nature of work carried out inside confined space.

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64. What is the procedure for entering a confined space hazards? OR What are the important PRECAUTIONS for confined space? 

Procedure for entering confined space:

1. Permit must be procured form operations, making sure of the following.

a. Complete isolation of the space to be entered.

b. Draining, depressurization and purging or cleaning should be performed.

c. Gas test should be conducted to ensure no hazardous atmosphere is present.

d. Space ventilation.

2. A Pre task meeting must be conducted with all authorized entrants prior to entering confined space.

3. The attendant (Stand by man) shall be assigned at the entrance to maintain communication with employees working inside to ensure their safety. A log book shall be maintained at the entrance to keep track of the people inside the space.

4. Safety attendant must be trained and authorized to use gas testing equipment.

5. Entrants must wear body harness, and if necessary a life line be attached to the harness to avoid entry-rescue.

6. Lighting should be provided, if necessary a maximum of 24 volts, lighting should be used attached a GFCI.

7. Only intrinsically safe or explosion-proof equipment shall be used inside.

8. Depending on the situation, emergency rescue team may be put on standby.

9. If an emergency occurs within the confined space, the standby person must not enter it until rescue team arrived.

10. Barricade the area with warning sign board.


65. What you know about working in a confined space entry? OR Explain about confined space entry? 

Any enclosure having a limited means of entry & exit and it is not designed for continuous employee occupancy.

 Before entering in the confined space, must need to obtained a confined space entry work permit, make sure that all required isolation being done.

 Frequently gas test is to be carried out to confirm that area is free of toxic gas or flammable atmosphere.

 If the area is contaminated or it has oxygen deficiency the provided BA sets or air line respiratory system.

 Conduct pre-task meeting for the employees who will be entering inside the confined area and get there signature to conform that they are aware of the hazards and safety measures.

 The attendant (Stand by man) to assigned at the entrance. A log book shall be maintained at the entrance to keep track of the people inside the space. The attendant shall not be assigned to other duties. If an emergency occurs within the confined space, the standby person must not enter it until rescue team arrived.

 The entering people should use body harness with lifeline for the emergency rescue purpose.

 Any required electrical lighting or tools should not exceed more than 24 volts and attached with GFCI / ELCB. It should be intrinsically safe or explosive proof.

 Barricade the area with warning sign board.

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66. Explain H2S? OR What is H2S and its characteristics explain?

• H2S is produced or generated by decomposition of organic materials.

• It is a highly toxic gas and highly flammable.

• Its smell like rotten egg at low concentrations and not detectable by order at high concentration.

• It is highly flammable. (flammable at 4.3% to 45.5% by volume in air)

• It is colourless.

• It is heavier than Air.(1.19)

• It is highly soluble in water and other liquid.

• When burned or flared it forms sulpher dioxide (SO2) which is also colorless and highly toxic gas.

• The exposure limits 10 PPM is the maximum allowed for 8 hours.

• Increasing exposure will cause headache and irritation of eyes.

• 800 PPM or more will be instantly fatal.

Exposure Limit: 

TLV-TWA of H2S = 10 ppm 

TLV-STEL of H2S = 15 ppm 

IDLH of H2S = 100 ppm 

Note: - Up to 10ppm work can be done without respiratory protection system. - 10 to 100ppm work can be done by SCBA or Air lined breathing apparatus. - Above 100ppm work not permitted, allowed only for rescue.


67. What are prominent H2S HAZARDS? 

H2S Hazards:

 Eyes and respiratory irritation.

 Dizziness, headache, nausea, abdominal pain.

 Loss of consciousness, Brain damage possible, death / fatal.

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68. Explain the precautionary measures to be taken while approaching H2S prone area? 

Precautionary Measures – H2S:

 Sufficient number of escape masks shall be kept in areas where H2S is liable to present.

 Incase H2S presence is suspected in an area, the persons must put on escape mask immediately and toxic gas test must be made immediately with appropriate detector to determined the concentration of H2S in air.

 Working person should be equipped with personal detectors and alarming device to alert in case of H2S presence.

Incase of H2S alarm, all personnel should vacate the area after donning the escape set / breathing apparatus and report to the designated assembly point for mustering.

 If working in H2S contaminated atmosphere must wear suitable BA set and work in pairs to support and rescue each other in the event of difficulties.

 Know the wind direction and evacuate in the cross wind direction incase of H2S leak.

 Never go to a low-lying area during H2S leak.

 Paste H2S warning sign in H2S prone areas.

 The presence or suspected of H2S in any part of the plant or sewer shall be reported immediately to supervisor and respective area fire station for arranging rescue and support.


69. How to treatment of persons affected by H2S? 

Positive pressure breathing apparatus must be worn by any persons attempting a rescue.

 The victim must be immediately moved to fresh air, possibly in the upwind direction of the gas leak. The rescuer must be outside the contaminated area before removing his/her personal BA set.

 If the victim has stopped breathing, resuscitation must be started immediately, using artificial respiration or a resuscitator if available. 

Resuscitation must be continued until the victim starts breathing unaided or until qualified medical assistance arrives. Medical help must be summoned as soon as possible.


70. Which type of fire extinguisher is used for each class of fire? TYPES OF EXTINGUISHERS & THEIR USE: (As Per KOC)

type of fire extinguisher
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Thanks for reading - Safety Interview Questions 7
Naitik Patel
Industrial Guide

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