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Hydrogen Sulfide and Iron Sulfide. Course Number NSTC-21 Revised 11–2010. Goal.

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Hydrogen Sulfide and Iron Sulfide

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Hydrogen sulfide and iron sulfide

Hydrogen Sulfide and Iron Sulfide

Course Number NSTC-21

Revised 11–2010

Hydrogen sulfide and iron sulfide


To ensure participants can recognize the hazardous characteristics of Hydrogen Sulfide (H2S) and Iron Sulfide (FeS) and be able to correctly apply the standards and procedures to safely perform work in areas where H2S and FeS are found.

Student instructions

Student Instructions

  • This self-paced course has 44 slides. The training is read-only – there is no narration. You must view this entire presentation before proceeding to the test.

  • After completing this slideshow you will be given a test. You may refer to this slideshow as a reference while completing your test. You must receive 100% on the test in order to receive credit for this course.



Participants will be able to:

  • Identify the characteristics of H2S.

  • List the hazards of H2S.

  • Describe the effects of the various H2S concentration levels on humans.

  • Recognize the need for monitors and alarms which identify the specific levels of H2S concentrations.



Participants will be able to:

  • Describe the proper notification procedures for an H2S emergency.

  • Describe the appropriate rescue and emergency treatment for a person exposed to high levels of H2S.

Introduction to h 2 s

Introduction to H2S

Characteristics of h 2 s

Characteristics of H2S

  • Highly toxic gas (deadly)

  • Colorless

  • Burns w/blue flame and produces Sulfur Dioxide (SO2)

  • Highly corrosive to certain metals (hydrogen embrittlement)

  • Flammable (LEL 4%~UEL 44% by volume)

  • Odor of rotten eggs or sulfur at low concentrations

  • Soluble in water

  • Heavier than air (VD=1.19)

  • Readily dispersed by wind movement

How is h 2 s formed

How Is H2S Formed?

  • H2S may be found naturally in swamps and sewers where it is formed during the decomposition of organic material.

  • It is present in unrefined carbon fuels and is formed during production when sulfate-reducing bacteria are introduced into an O2 deficient atmosphere where those materials are present. An example would be the injection of untreated sea water into a well to increase formation pressure.

Where is h 2 s found

Where Is H2S Found?

  • Natural & Industrial Settings

  • Produced Water Systems

  • Ullage/Headspace (temporary overflow)

  • Drain Systems

  • Vent Gas Systems

  • TEG Effluent Streams

  • Crude Streams

  • Dead Legs

  • Abandoned Systems

  • Wellhead Cellars

Warning signs for h 2 s designated areas

Warning Signs for H2S Designated Areas

Modules and facilities will be designated as H2S areas when they contain a process stream with H2S concentrations in the vapor phase greater than 100 ppm. Entrances to these areas are marked with a CAUTION sign.

ASH, page 157; BP ASH , page 77

Warning signs for h 2 s designated areas1

Warning Signs for H2S Designated Areas

H2S designated wellhouse shelters with a process stream at or greater than 300 ppm will be identified with a Danger Sign and shall be tested prior to each entry.

ASH, page 158; BP ASH, page 78

Effects of h 2 s exposure

Effects of H2S Exposure

How h 2 s enters the body

How H2S Enters the Body

Effects of inhaling h 2 s

Effects of Inhaling H2S

  • Loss of smell occurs within 2–2.5 minutes at 100 ppm.

  • Loss of consciousness occurs at 500 ppm.

  • Asphyxiation occurs at concentrations greater than 1000 ppm.

  • Exposure to high concentrations of H2S should not have lasting effects if the person is quickly revived.

Factors that affect exposure

Factors that Affect Exposure

  • Duration (Time)

  • Frequency (Number of exposures)

  • Intensity (Concentration)

  • Individual Susceptibility

Physical symptoms of short term low level h 2 s exposure

Physical Symptoms of Short Term, Low Level H2S Exposure

  • Skin / eye irritation (10–50 ppm)

  • Dryness in throat and mouth (50–100 ppm)

  • Nausea (100–200 ppm)

  • Headache / dizziness (100–200 ppm)

  • Coughing (100–200 ppm)

Physical symptoms of long term low level h 2 s exposure

Physical Symptoms of Long Term, Low Level H2S Exposure

  • Skin / eye irritation

  • Fatigue

  • Loss of appetite

  • Headaches

  • Illogical thinking

  • Irrational behavior

  • Dryness in throat and mouth

  • Coughing

  • Loss of consciousness

Responses to h 2 s

Responses to H2S

Responses to h 2 s1

Responses to H2S

H 2 s detection devices

H2S Detection Devices

Types of monitors

Types of Monitors

  • Personal Monitors

    • Examples: ISC T40 Rattler, Gas Badge Plus, BW, MS Tox: worn by employee on outside of clothing

  • Electronic Portable Monitors

    • Examples: ISC LTX 310/312 Multi-Gas Monitor (1–3 gas)

    • TMX 410/412 Multi-Gas Monitor (1–4 gas)

    • ITX Multi-Gas Monitor (1–6 gas)

Types of monitors1

Types of Monitors

  • Fixed Electronic Sensors

    • Hardwired gas detection

    • Visual/audible alarms and display monitors

Protection against h 2 s hazards

Protection Against H2S Hazards

Protection measures

Protection Measures

  • Personnel Training, Roles and Responsibilities

  • Safety Equipment: Supplied Air or Self-Contained Breathing Apparatus (SCBA)

  • Emergency Procedures and Contingency Plans

  • Safe Work Practices and Permits

Unit operator or issuing authority responsibilities

Unit Operator or Issuing Authority Responsibilities

  • Perform necessary H2S gas checks.

  • Note on permits where H2S could be present.

  • Check that personnel are using personal monitors in H2S designated areas.

  • Check that personnel are wearing supplied breathing air when working in an area where H2S exceeds 10 ppm.

ASH, page 155; BP ASH, page 76

First line supervisor or area authority responsibilities

First Line Supervisor or Area Authority Responsibilities

Ensure all H2S related activities are in accordance with company standards.

ASH, page 155; BP ASH, pages 76-77

Company or contractor work group leader responsibilities

Company or Contractor Work Group Leader Responsibilities

  • Contact Control Room/DS/Well Pad Operator for approval to enter the H2S designated area.

  • Ensure personnel are H2S trained and provide documentation on request.

  • Provide pre-job review with personnel of facility alarms, evacuation routes, assembly points, etc.

  • Provide protective equipment and monitors.

ASH, pages 155–156; BP ASH, page 77

Company or contractor work group leader responsibilities1

Company or Contractor Work Group Leader Responsibilities

  • Be aware of the wind direction and choose an evacuation path accordingly.

  • Conduct personnel head count after an evacuation, H2S or gas alarm and report status to Control Room or Drillsite / Well Pad Operator.

  • Assign a trained back-up, with ready access to supplied breathing air, when working in H2S atmospheres of 10 ppm or greater.

ASH, page 156; BP ASH, page 77

Worker responsibilities

Worker Responsibilities

  • Know and understand the H2S facility alarms.

  • Provide evidence of required H2S training upon request.

  • Have the training and ability to properly use supplied air breathing apparatus if required to assist in rescue or facility isolation.

  • Report to the designated briefing area for accountability upon hearing an alarm.

  • Leave the area at once if levels of H2S are 10 ppm or greater and notify Operations personnel.

ASH, page 156; BP ASH, page 77

Safety measures at the job site

Safety Measures at the Job Site

  • Identify site specific rules, routes, and primary and secondary safe areas.

  • Observe conditions, signs, and audio/visual alarms.

  • Check wind direction.

  • Evacuate up wind.

  • Look for personnel and their activity.

Safety measures at the job site1

Safety Measures at the Job Site

  • Enter the job site cautiously.

  • Have a minimum of two escape routes.

  • Always be aware of surrounding conditions.

  • Provide for continuous gas monitoring.

Safety measures at the job site2

Safety Measures at the Job Site

  • Personal gas monitors shall be worn at all times in an H2S designated area.

  • When more than one individual will be working in the same area, at least one personal monitor shall be assigned to the group as determined by the Work Group Leader or Supervisor.

ASH, page 158; BP ASH, page 78

Information for reporting emergencies

Information for Reporting Emergencies

  • Your name

  • Location of the emergency

  • Nature of the emergency

  • What is involved

  • Number of personnel involved, if any

  • Other information that you have

  • Your phone, beeper & radio call sign

Rescue procedures

Rescue Procedures

  • Evacuate the area

  • Activate the emergency response system

  • Call the emergency number from safe phone

  • Warn other people away from the affected area

Trained rescuers

Trained Rescuers

Contact qualified back-up help


Move victim to fresh air (TWO individuals rescue while TWO stand by)

Begin CPR

Do not leave victim unattended

Report the incident to the Medical Facility

Always be aware of the hazards of h 2 s

Always Be Aware of the Hazards of H2S

Introduction to iron sulfide fes

Introduction to Iron Sulfide (FeS)



Participants will be able to:

  • Identify iron sulfide sources in the workplace.

  • Explain the hazards of iron sulfide.

  • Identify appropriate practices to minimize exposures to personnel and property while opening any tank, vessel, or piping which has contained a hydrocarbon product and may contain iron sulfide.

What is iron sulfide

What Is Iron Sulfide?

  • Iron sulfide is iron that has reacted with hydrogen sulfide (H2S) in an oxygen deficient environment.

  • Iron sulfide has the formula FeS.

  • Iron sulfide may be commonly referred to as ferrous sulfide.

Where is iron sulfide found

Where is Iron Sulfide Found?

  • Iron sulfide may be present in petroleum process equipment that is in H2S service such as piping, vessels, tanks, and exchangers.

  • It may be present in scale, sediment or sludge inside process equipment and piping.

ASH, page 158; BP ASH, pages 78-79

Iron sulfide hazards

Iron Sulfide Hazards

  • Iron sulfide is pyrophoric. It will ignite in the presence of ambient air without an ignition source.

  • Burning iron sulfide may emit toxic fumes of sulfur dioxide (SO2).

ASH, page 158; BP ASH, pages 78-79

Iron sulfide control measures

Iron Sulfide Control Measures

  • Prior to opening process equipment that potentially contains iron sulfide, every effort shall be made to clean the equipment by water washing or steam cleaning.

  • Keep equipment and vessel internals wetted until laboratory analysis determines if the sludge or scale is non-pyrophoric.

ASH, page 158; BP ASH , pages 78-79

Iron sulfide control measures1

Iron Sulfide Control Measures

  • All iron sulfide removed from equipment should be immediately discarded into metal containers with tight fitting lids and wetted thoroughly.

  • It should then be labeled and disposed of according to the Alaska Waste Disposal & Reuse Guide (Red Book).

  • If iron sulfide does ignite, SCBA’s must be used while extinguishing the fire with water.

ASH, page 158 ; BP ASH, pages 78-79



  • Know the hazards of hydrogen sulfide and iron sulfide and where they are located.

  • Take precautions to protect yourself and others against these dangerous hazards.

  • Follow proper procedures for entering areas which may contain hydrogen sulfide and/or iron sulfide.

  • Follow proper emergency procedures.

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