Hydrogen SulfideSafety Program

PurposeTo inform personnel of the dangers of HydrogenSulfide (H2S) and how to protect themselvesfrom exposure to this gas.

ScopeThis program was chosen to be established foremergencies that may potentially arise fromexposure to Hydrogen Sulfide.

Hydrogen Sulfide

This gas can accumulate in sewers or sewagetreatment plants due to its presence inpetroleum. Well drillers, tunnel workers, andminers may be exposed if an undergroundpocket is discovered. While Hydrogen Sulfideoccurs naturally in the Earth via crudepetroleum and natural gases, it may also resultfrom the following:

RefineriesWastewater treatment facilitiesSulfur productionTar and asphalt manufacturing plantsThe breakdown of human and animalwastes by bacteriaIndustrial activities such as food processingCoke ovensKraft paper millsRayon textile manufacturingTanneries

Occurrence

Hydrogen Sulfide is a colorless and poisonousflammable gas that is known for smelling stronglyof rotten eggs. Detection can occur atconcentrations ranging from .01-.03 parts permillions. Relying on detection via smell is dangerousbecause a ppm of above 100 can deaden aperson’s sense of smell in minutes. If rust orcorrosion deposits exist, Hydrogen Sulfide mayreact to become Iron Sulfide which can ignitespontaneously when combined with air.

Properties

High concentrations of Hydrogen Sulfide can catchfire or explode near a source of ignition. Othertoxic gases can be formed upon the ignition of thisgas and may further react with those toxins.

Explosive Properties

OSHA ceiling = 20 ppmOSHA maximum peak = 50 ppm)NIOSH IDLH = 100 ppmAIHA ERPG-2 = 30 ppm

Various agencies of the US government have setthe following standards for H2S exposure:

Limits

Exposure Limits

Health Effects

Hydrogen sulfide is extremely toxic. Workers areexposed when they inhale hydrogen sulfide in theair, and this toxic gas is quickly absorbed by thelungs. It is believed that exposure to hydrogensulfide prevents the brain from using oxygen.

Toxicity

Short–term (acute) exposure to hydrogen sulfidecan cause irritation to the nose, throat, eyes andlungs. Exposure to higher concentrations can causevery serious health effects, and even death. Thefollowing table will show some key numbers andhealth effects:

Short Term Exposure

0.01 - 0.3 Odor threshold

1 - 20 Offensive odor, possible nausea,tearing of the eyes or headaches withprolonged exposure

20 - 50 Nose, throat and lung irritation;digestive upset and loss of appetite;sense of smell starts to become fatigued;acute conjunctivitis may occur (pain,tearing and light sensitivity)

100 - 200 Severe nose, throat and lung irritation;ability to smell odor completelydisappears.

250 - 500 Pulmonary edema (buildup of fluid inthe lungs)

500 Severe lung irritation, excitement,headache, dizziness, staggering, suddencollapse (knockdown), unconsciousnessand death within a few hours, loss ofmemory for the period of exposure

500 - 1000 Respiratory paralysis, irregularheartbeat, collapse and death withoutrescue.

> 1000 Rapid collapse and death

Health EffectConcentration(ppm)

Health Effects

It is important to note that the symptoms ofpulmonary edema (buildup of fluid in the lungs),such as chest pain or shortness of breath, can bedelayed for up to 72 hours after exposure.

Pulmonary Edema

Workers who survive a serious hydrogen sulfideexposure (concentrations above 500 ppm) mayrecover completely or suffer long-term health effects.In some cases, there can be permanent nervoussystem effects, such as fatigue, anxiety, irritability, or impaired learning and memory. Workers whoexperience unconsciousness tend to have a greaterchance of having permanent effects to therespiratory system, with symptoms such as shortnessof breath on exertion, wheezing, chest tightness,hypersensitive airways and permanent lung damage.

Acute Exposure Recovery

Health Effects

Hydrogen sulfide does not accumulate in the body.Repeated or prolonged exposure may cause lowblood pressure, headache, nausea, loss of appetite,eye inflammation, and chronic cough.

Long Term Exposure

Health Effects

The following health effects due to long-term(chronic) exposure to hydrogen sulfide have alsobeen reported in scientific literature:

Chronic Exposure Effects

Reduced lung functionNeurological effects, such as headaches,nausea, depression, weakness, personalitychanges. Exposure to other reduced sulfurgases such as dimethyl sulfide and thiols(mercaptans) at the same time may contributeto this effectEye irritationIrritation to the mucous membranesDamage to the cardiovascular system

Health Effects

The following first aid measures should be followedfor exposure to H2S:

First Aid

First, immediately remove the victim from furtherexposure. Designated rescuers must wear properlyfitting, positive pressure self-contained breathingapparatus other required safety equipmentappropriate to the work site. If the worker is notbreathing, apply cardio-pulmonary resuscitation inthe nearest safe area. Remove contaminatedclothing but keep the individual warm. If theindividual is conscious, keep them at rest. 

Health Effects

Be aware of possible accompanying injuries(e.g. the victim may have fallen when they wereovercome) and treat them accordinglyIf the victim’s eyes are red and painful, flushwith large amounts of clean water for at least15 minutesEnsure the worker receives medical care assoon as possible. The worker must not beallowed to return to work or other activities

First Aid

Preventative Measures

Engineering controls are used to eliminateexposure to a substance. Engineering controlsremove the substance from the air or provide abarrier between the worker and the substance. Forexample:

Engineering Controls

Ventilation to control hydrogen sulfideconcentrations in the airClosed systems that vent to a flareTreatment methods to remove hydrogen sulfidefrom liquid and gas streams

Preventative Measures

Flaring is controlled burning of gas. It’s a techniqueused by the petroleum industry to remove wastegases from crude oil. However, when hydrogensulfide is burned, another toxic gas, sulfur dioxide,is produced. Therefore, flaring is becoming a lesspopular way of dealing with waste gases inpetroleum products.

Flaring

Preventative Measures

Chemical treatment can be used to removehydrogen sulfide from crude oil, gas and waterstreams. The most common method is called theClaus Process where hydrogen sulfide is separatedfrom the gas stream by amine treatment and thenconverted to less toxic element sulfur usingcombustion and chemical reaction.

Where hydrogen sulfide is present in off-gasesfrom wastewater treatment or other industrialprocesses, there are a variety of scrubbers andfilters that can be used. In water, hydrogen sulfidecan be treated by chlorination, manganesegreensand filters, aeration, ozonation, activatedcarbon and bio-filters. Hydrogen sulfide treatmentof drilling fluids, along with proper pH control,should be used to reduce the amount of hydrogensulfide that is re-circulated.

Chemical Treatment

Preventative Measures

Educating workers about the hazardsassociated with hydrogen sulfide and symptomsof overexposure.Courses such as “H2S Alive” and First Aid arerecommended when workers may be exposed tohydrogen sulfide at the work site.Developing safe work procedures forenvironments that may contain hydrogensulfideUsing engineering controls and otherequipment to reduce exposureUsing personal or area monitoring equipment,with alarms, where there are potential sourcesof hydrogen sulfide.

Work practices that can be implemented to reducepotential exposure to hydrogen sulfide include:

Administrative Controls

Preventative Measures

Evaluating the hazard from hydrogen sulfide mustbe included in the hazard assessment for the worksite. Below are some pertinent questions to measureyour sites preparedness.

Safe Work Practices

Preparedness Questions

Has the potential for a release of H2S into theatmosphere at levels of 10 ppm or greater beenevaluated?Does every worker on site know where and howan uncontrolled release of H2S could occur?Does every worker know what precautions totake when there is a potential for an H2Srelease?Do workers know what to do in case of anemergency?Have the areas which require the mandatoryuse of breathing apparatus been identified?Does every worker who could be exposed toH2S have appropriate training?Is there a procedure to test the atmosphere forH2S concentrations and are workers trained inthis procedure?Is all the necessary equipment readily availableto workers who require it?

Preparedness Questions

Are you certain that your workers follow safework practices developed by your organization?Have you determined if you need a code ofpractice for operations involving H2S?

If the answer to any of the questions is “no”, workersmay be in danger from exposure to hydrogensulfide.

There is a variety of monitoring equipmentavailable, depending on the purpose of themonitoring. It is important to select monitoringequipment that fits the needs of the workenvironment. When selecting monitoring equipment,the user should also check for substances that couldinterfere with the equipment.

Monitoring equipment for hydrogen sulfide shouldbe set to alarm at no higher than the OEL forhydrogen sulfide. Portable monitors will alarm at theappropriate PEL of 20 PPM for 1910 or 10 PPM for1926. It is also very important that the instrument becalibrated and operated properly.

Monitoring

Hydrogen sulfide is frequently encountered in workenvironments (e.g. oil and gas industry, sewagetreatment plants) where other flammable orcombustible gases are present. In these workenvironments, it is recommended that monitoring bedone for both hydrogen sulfide and otherflammable/combustible vapors so the hazards canbe properly assessed.

Monitoring

If it is not practicable or feasible to use engineeringor administrative controls to reduce the potential forexposure to hydrogen sulfide, or if these measuresare not sufficient, Wetherbee Electric, Inc. willprovide workers with appropriate respiratoryprotective equipment. There are many types ofrespirators available and it is important to selectthe correct level of respiratory protection.

Personal Protective Equipment

Since hydrogen sulfide is irritating to the eyes, air-tight goggles or full-face respirator masks should beworn. A full-facepiece, positive pressure supplied airrespirator is needed for work areas where hydrogensulfide concentrations exceed the OEL. TheNational Institute for Occupational Safety andHealth (NIOSH) specifies an immediatelydangerous to life or health concentration forhydrogen sulfide as 100 ppm. Above theseconcentrations, or for emergency or planned entryinto unknown concentrations, a full-facepiecepositive pressure supplied air respirator must beused. Whatever the type of respirator used, theworker must be clean-shaven where it seals to theskin of the face and must be fit-tested for the typeof equipment being used.

Personal Protective Equipment

Code of PracticeA code of practice is required for work sites wherethere may be more than 10 kg of hydrogen sulfidepresent as a pure substance, or in a mixture in aconcentration over 0.1% by weight and at least 10kg of hydrogen sulfide in aggregate.

Company policy and persons responsible forthe code of practiceSafe work proceduresRequired personal protective equipmentWorker training requirements if neededH2S certificationEmergency procedures and designatedemergency personnel.Alarms (personals and/or stationary)Wind socks will be established and in view ofthe work areaDeveloping egress routes to safe zones whenalarms soundBe aware of client’s contingency/emergencyplans

Code of Practice

The code of practice should include:

Contents

Exposure Monitoring

When conducting monitoring for hydrogen sulfideto comply with the OEL, either NIOSH Method6013, or a continuous reading direct readinginstrument may be used.

Methods

When a direct-reading instrument is used tomeasure hydrogen sulfide exposure, it must beused, calibrated and maintained according to themanufacturer’s instructions. The employer isresponsible to ensure that the instrument isoperating properly when it is used at the work site.

Calibration and Maintenance

Additional Requirements

Development of safe work procedures.Ensuring that an emergency response plan isdeveloped for the work site and that personnelare designated for emergency responseactivities.Training, personal protective equipment andother equipment needed. Training of workerson health hazards associated with exposure tohydrogen sulfideEnsuring that the need for ventilation isproperly assessed and systems that areinstalled are properly designed andmaintained. Workers also need to be trained onthe proper operation of these systems.

Training

All employees will be trained in the hazards of H2Supon being hired or assigned to a job that has thepotential to expose the employee to H2S. Trainingtakes 3-4 hours and will include the following:

Physical and chemical propertiesSourcesHuman physiology and medical evaluationWork proceduresPersonal Protective EquipmentContingency plans and emergency responseBurning, flaring, and ventingState and federal regulatory requirementsRelease dispersion modelsDetection and monitoringEngineering controls

FrequencyAfter initial training, employees will be retrainedannually.

Wetherbee Electric, Inc. was established in Oklahoma in1899. For over 120 years, our company has been shaped bya tradition of excellence. Wetherbee Electric has cultivatedstrong relationships inside Oklahoma and out.

Our construction projects have ranged from Montana toTexas, and California to Maine. We even have offshoreexperience in Puerto Rico and the Isle of Trinidad.

We are your single source integrator for parkingaccess, security, and electrical projects.

Office Address

Wetherbee Electric, Inc.516 N. Villa,Oklahoma City,Oklahoma 73107

p: 405.236.2606 | e: info@wetherbeeinc.com | lic #: OK 58111 / AC1275

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