Introduction
This article is specifically prepared to provide Oil and Gas Interview Questions and Answers. This oil and gas interview material is based on the questions asked by an expert or specialist at a major oil and gas organisation during the interview session.
This oil and gas interview questions and answers will really help those who want to start their careers in oil and gas as HSE Officers or in any oil and gas job trade, because safety knowledge is essential for everyone who wants to work in the industry.
Q1: What are Zone 0, Zone 1 & Zone 2?
Ans: Zones are a classification of areas of hazards contained within an area:
Zone 0: Zone 0 is an area where explosive material in the form of flammable gases, mist, or mixture with air is continuously present for a long period of time, e.g., a gas storage area.
Zone 1: Zone 1 is an area where an explosive atmosphere is likely to occur in normal operation and present occasionally, e.g., around flanges and valves.
Zone 2: Zone 2 is an area where an explosive atmosphere is not likely to occur in normal operation or if it persists only for a short period.
Q.2: What are the major hazards associated with a plant shutdown? (Mention at least five.)
Ans: 1: Fire due to extensive hot work with plant shutdown.
2: Mechanical Hazards, (Noise (due to machinery operation like a compressor).
3: Residual Energy (Toxic gases or hydrocarbon (If LEL not 0 or some gases or hydrocarbon pockets present in process lines, not isolated properly or drained).
4: Work at Height and Lifting (Fall objects). As a simultaneous activity, at different level’s platform is started, and a lifting activity is also carried out during shutdown, which can lead to the fall of objects
5: Confined Space (Activity in confined spaces associated with different hazards).
6: Fatigue and Human Errors (Extended working hours, a large number of workers involved during shutdown).
Q.3: What are the major hazardous activities in a shutdown?
Ans: There are a lot of activities that are hazardous during shutdown and require proper control and risk assessments, hazards identification, and JSA as a control for those activities to perform safely and comply with company safety policy and safety standards. Some of them are as follows:
- Confined Space.
- Lifting.
- Hot Work. (Open Flame cut and weld)
- Hydro Jetting.
- Sand & Grit Blasting.
- Electrical.
- Painting.
- Civil Activities.
The above-mentioned activity is mainly performed during the shutdown, and hazards associated with those activities are all types of hazards. Mechanical, Chemical, Biological, Ergonomics, and Psychological Hazards. Those hazards can be prevented through applying proper control, administrative and engineering control, and through teamwork.
NOTE: This oil and gas interview questions and answers is for HSE officers and anyone who wants to start his carrer in oil and gas industry
Q.4: What are the types of gas testing in a plant (or SD)?
Ans: Gas testing in the plant during shutdown is done by fixed and portable gas detectors MX4 and MX6. The gases tested are Oxygen, H2S, CO, LEL, N2, and SO2.
Gas testing is done in 2 stages: pre-entry gas testing and continuous gas monitoring.
Q.5: What are the causes of oxygen enrichment in a confined space?
Ans: Oxygen enrichment in confined spaces is due to the gas cutting activity in confined spaces.
Use of oxygen for ventilation and cooling is strictly prohibited.
Q.6: What are the hazards of oxygen enrichment?
Ans: Hazards of oxygen enrichment are fire and explosion.
Q.7: Results/ Hazards of oxygen deficiency in stages?
Ans: 16–19.5% O₂
↓ Reduced concentration, impaired judgment, increased breathing rate
- 12–16% O₂
↓ Dizziness, headache, fatigue, poor coordination
- 10–12% O₂
↓ Nausea, vomiting, loss of consciousness
- 6–10% O₂
↓ Fainting, severe respiratory distress, risk of death
- Below 6% O₂
↓ Immediate unconsciousness, cardiac arrest, fatal within minutes.
NOTE: This oil and gas interview preparation is for HSE officers and anyone who wants to start his carrer in the oil and gas industry
Q.8: How will you identify the presence of H2S gas?
Ans: At low concentration, H2S has a smell like rotten egg, but at high concentration, it is odorless. Personal gas detector alarm at 10PPM and above. So, we can leave the area after the H2S alarm, so continuous gas monitoring is requiring at H2S area.
Q.9: What is the standard (rating) for H2S gas?
Ans: Standard rating of H2S gas depends on the PPM in air. The PEL or TWA of H2S is 0 to 10PPM for 8 hours a day, above 10 to 15 STEL is applicable, which is for 15 minutes four times a day. Above this concentration, SCABA or SABA required above 100PM is IDLH.
Q:10 1 PPM of H2S is equivalent to what percentage?
Ans: 1 PPM of H2S is 0.0001%. Because it’s a silent killer gas, we measure in PPM, not percentage.
Q.11: What is the IDLH for H2S gas?
Ans: Concentration greater than or equal to 100PPM is IDLH.
NOTE: This oil and gas interview questions and answers, is for HSE officers and anyone who wants to start his career in oil and gas industry
Q.12: 2% of H2S is equivalent to how many PPM?
Ans: 1%= 10000 PPM.
2*10,000= 2000PPM.
Q.13: What is static energy? How is it produced? How to neutralize it?
Ans: Electrical charge accumulated on an insulated material or liquid/solid is called static energy, and it can ignite flammable vapors in air.
It is produced through friction between two materials. It (Engineer, 2026)can be neutralized through the grounding of equipment and personnel.
Q.14: What is a breathing apparatus? Its limits?
Ans: Breathing apparatus is a device which provide air to the personnel in less oxygen environment or toxic gases. They are of different types: self-contained and supplied air. SCABA Limit is 30 min, and SABA has 2 hours limit per cylinder.
NOTE: This oil and gas interview questions and answers, is for HSE officers and anyone who wants to start his career in oil and gas industry
Q.15: What is the PEL for H2S gas?
Ans: PEL for H2S gas is 5PPM for 8 hours per day and 5 days a week.
Q.16: When there is no oxygen, then which kind of gas monitor will be used?
Ans: When there is no oxygen, an IR(infrared) gas detector is used, which can detect hydrocarbons even in a low-oxygen environment.
Q.17: What is hydro jetting activity?
Ans: Hydro jetting is a process used during industrial or plant shutdowns to clean equipment of industrial waste and pyrophoric materials. This procedure involves using high-pressure water pumps and specialised equipment. It is a hazardous activity that requires strict safety controls.
NOTE: This oil and gas interview questions and answers, is for HSE officers and anyone who wants to start his career in oil and gas industry
Q.18: What are the engineering controls for hydro-jetting activity?
Ans: Engineering controls for hydro jetting activity,
- Rupture Disk.
- Dead Men Switch.
- PSV or PRV.
- Pressure-rated hoses and fittings.
Q.19: What are the major hazards associated with hydro-jetting activity?
Ans: Major Hazards associated with hydro-jetting are,
- High Pressure. (If pressure is uncontrolled can damage people and property)
- Flying Debris.
- Slips, Trips, and Falls.
Q.20: What will you check on the hydro-jetting machine?
Ans: As a safety officer, I’ll check the machine before the start of the hydro-jetting activity.
Daily checklist must be filled and available onsite, checking the condition of the machine by ensuring:
- Company Inspection sticker.
- Valid Certification and pressure test record.
- Pressure rating of hoses and fittings. (Whip check and safety pins placed).
- Conditions of hoses. (No cuts and damage).
- Dead-Man functions properly.
- The emergency stop is accessible and working.
Conclusion
This oil and gas interview questions and answers, is for HSE officers and anyone who wants to start his career in the oil and gas industry. We will try to publish more real experience based frequent asked questions in real-time interview sessions in the oil and gas.