hydrogen sulfide and iron sulfide

© 1997-2010 North Slope Training Cooperative—revised 2010. All rights reserved.

Hydrogen Sulfide and Iron Sulfide Course Number

NSTC-21

Revised 11–2010

© 1997-2010 North Slope Training Cooperative—revised 2010. All rights reserved. Course Number: NSTC-21

2Goal

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.


3Objectives

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.


4


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.

Objectives


5

Introduction to H2S


6Characteristics 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


7How 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.


8Where 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


9

ASH, page 157; BP ASH , page 77

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.


10

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.

Warning Signs for H2S Designated Areas

ASH, page 158; BP ASH, page 78


11

Effects of H2S Exposure


12How H2S Enters the Body


13Effects 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 have not lasting effects if the person is quickly revived.


14Factors that Affect Exposure

Duration (Time)

Frequency (Number of exposures)

Intensity (Concentration)

Individual Susceptibility


15

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)


16

Skin / eye irritation

Fatigue

Loss of appetite

Headaches

Illogical thinking

Physical Symptoms of Long Term, Low Level H2S Exposure

Irrational behavior

Dryness in throat and mouth

Coughing

Loss of consciousness


17Responses to H2S

Concentration Response

< 1 ppm Lower odor threshold

10 ppm Personal alarm should sound

>10 ppm Supplied air respirator required

100 ppm IDLH (NIOSH)


18Responses to H2S

Concentration Response

150–500 ppm Olfactory nerve paralysis

500–700 ppm Loss of consciousness; death 30+ minutes

700–1000 ppm Rapid unconsciousness; death

1000–2000 ppm Immediate unconsciousness; death in a few minutes


19

H2S Detection Devices


20Types 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)


21Types of Monitors

Fixed Electronic Sensors

Hardwired gas detection

Visual/audible alarms and display monitors


22

Protection Against H2S Hazards


23Protection 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


24

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.



25

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


26

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


27

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.



28

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.

Worker Responsibilities



29

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.


30


Enter the job site cautiously.

Have a minimum of two escape routes.

Always be aware of surrounding conditions.

Provide for continuous gas monitoring.


31


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.



32

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


33Rescue Procedures

Evacuate the area

Activate the emergency response system

Call the emergency number from safe phone

Warn other people away from the affected area


34Trained Rescuers

Contact qualified back-up help

Don SCBA

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


35

Always Be Aware of the Hazards of H2S


36

Introduction to Iron Sulfide (FeS)


37Objectives


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.


38What 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.


39Where 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.



40Iron 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).



41

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


42

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


43Summary

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.

hydrogen sulfide and iron sulfide

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