H2S HAZARDS and CONTROLS IN INDUSTRY.ppt

H2S HAZARDS and CONTROLS

1. H
2SHAZARDS &
CONTROL

2. H
2SHAZARDS
H
2Sor hydrogen sulfide is one of the most common
and serious hazards faced in the petroleum
industry.
It is present in many operations within ARL. Like
DHDS, SRU, Amine Unit and Sour water Stripper

3. H
2S-What Is It? Where Does It
Occur?
H
2S is a colorless, highly flammable gas. It has a pungent
odor which smells like rotten eggs. Uncontrolled, it can be
deadly.
H
2Sis naturally present in most fossil fuels and occurs as a
by-product during the production and processing of petroleum
and gas. It can also be produced during metal refining, pulp
and paper production, and sewage and waste water
treatment.

4. H
2SPROPERTIES
Toxic
Colorless
Soluble
Heavier than air (10 times heavier than air)
Flammable & explosive (260 deg C Auto ignition and 4 to 46
% explosive range)
Corrosive (reacts with metals and results in corrosion)

5. Exposure Limits
ImmediatelyDangeroustoLifeorHealth:100ppm
ShortTermExposureLimit:15ppmfora15-minuteavg.
Permissible Exposure Limit: 10 ppm for an 8-hr period avg.

6. Concentration Levels & Effects
Concentration Health Effects
10 ppm Beginning eye irritation
50-100 ppm Slight respiratory tract irritation after 1 hour exposure.
100 ppm Coughing, eye irritation, loss of sense of smell after 2-15 minutes. Altered
respiration, pain in the eyes, and drowsiness after 15-30 minutes followed by
throat irritation after 1 hour. Several hours exposure results in gradual increase
in severity of these symptoms and death may occur within the next 48 hours
200-300 ppm Severe respiratory tract irritation after 1 hour of exposure. Possible pulmonary
edema (fluid in the lungs).
500-700 ppm Loss of consciousness and possibly death in 30 minutes to 1 hour.
700-1,000 ppm Rapid unconsciousness, loss of respiration, and deathafter 1-3 minutes.
1,000-2,000ppm Unconsciousness at once, loss of respiration and death in a few minutes. Death
may occur even if individual is removed to fresh air at once.

7. H
2SHazard Control
Engineering Measures
Detection
Respiratory Protection
Effective Training

8. H
2SHazard Control
Engineering Measures
Safe Design of Process Equipment
Regular Equipment Maintenance
Proper Ventilation
Control of Leaks

9. H
2SHazard Control
Detection
Areas with H2S to be monitored
Fixed-Area H2S Monitor
Portable Gas Monitor

10. H
2SHazard Control
Respiratory Protection
Self-Contained Breathing
Apparatus (SCBA)
Supplied Air Breathing Apparatus
(SABA)
Emergency Escape bottle

11. H
2SHazard Control
Effective Training
Recognition of a leak or release of H
2S
H
2Semergency response plan for the area
Identification of H
2Salarms and warning lights
Location of emergency exits
Recognition of wind direction with wind socks or flags

12. H
2SHazard Control
Effective Training
Instruction to escape upwind or crosswind
Use of emergency escape equipment
Use of emergency telephone numbers
Location of safe assembly areas
Use of air-monitoring devices

13. H
2SHazard Control
Effective Training
Use of respiratory protection equipment
Necessity of “No smoking” rules in high risk areas
Practice of rescue procedures
Practice of rescue breathing and cardiopulmonary resuscitation
(CPR)

14. SRU/ AMU/ SWS
Occupational Health Monitoring
•Gastec dositubes used for detection of H2S dosage
•If more than 10 ppm dosage, referred to doctor for
checkup
•Usually Thiosulfate in urine is checked
•Gas detectors kept with the Ops/ Maintenance personnel
to warn of the H2S concentration
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15. SRU/ AMU/ SWS
Pump Maintenance
•Proper flushing/ decontamination is ensured before
handing over for maintenance
•Lead acetate paper is used to confirm the presence of
H2S. If no color change, then H2S content is Nil
•Water is showered as an additional precaution when nuts/
bolts are loosened
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16. SRU/ AMU/ SWS
Shutdown jobs/ Vessels Cleaning
•Confined Space entry permit is used, verifying the H2S,
Oxygen content, HC to the desired level
•Jobs are done with the help of air line.
•Following is the specification for air supplied to the user
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Sr.
No
Parameter Value
1 Oxygen content 19.5-23.5 %
2 Hydrocarbon (condensed) 5 mg/ m3
3 Carbon Monoxide 10 ppm
4 Carbon Dioxide 1000 ppm
5 Moisture Dew point 10 deg
F below ambient
6 Lack of noticeable odor

17. SRU/ AMU/ SWS
Mechanical Integrity and Process Parameters
•Pin holes PWHT of Lean Amine Lines
•Sour Water Stripper (SWS) Tank roof leakage issues
(H2S in vapor phase is more corrosive than liquid)
•pH of amine is critical in controlling corrosion
•If temperature drops below 120 deg C, solidification of
sulfur occurs and lines get blocked.
•One cubic meter increase in air can lead to increase in
100 deg C temperature.
•Main Combustion Chamber (Thickness loss, refractory
detach, hot spots on casing)
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18. SRU/ AMU/ SWS
Emergency Equipments
•Air Line meeting specification OSHA Grade D Quality
•Emergency Life Saving Equipment (ELSA) for escape
only (10-15 mins time)
•Self Contained Breathing Apparatus (SCBA)
•Gas Detectors installed in the field
•Flashing light with audible alarms
•Personal gas detection meter (mandatory)
•Trolley mounted Breathing apparatus
•Gas Masks (only for escape) not for working
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