HYDROGEN HYDROGEN SULFIDESULFIDESAFETYSAFETY

Safety Moment…

Anybody

Anything

Anytime

Anywhere

Basis for this course:

Millions of workers are exposed to hydrogen sulfide hazards.

Hydrogen Sulfide is very safe under controlled conditions. Employees must understand the hazards of hydrogen

sulfide. Each year, numerous accidents occur with hydrogen

sulfide. Safety can be greatly enhanced if training is provided. OSHA Standards require:

Hazards be assessed. Training be conducted. Hazards and precautions be explained. Emergency response capability be established.

Course objectives

Provide an Introduction to the Toxicology of Hydrogen Sulfide.

Discuss Hydrogen Sulfide’s Usage in Today’s Industry. Discuss General Terms Used in Hydrogen Sulfide Safety. Discuss Methods of Compliance with Hydrogen Sulfide

Safety. Discuss the Routes of Entry Into the Human Body. Discuss Any Medical Surveillance Requirements. Discuss Personal Protective Equipment Requirements. Discuss the Hazards of Hydrogen Sulfide Upon the Human

Body. Discuss Hazard Recognition & Control Skills.

Course contents

Factors Influencing Toxic Action Exposure Terminology Factors Affecting Exposure Methods of Compliance Exposure Control Basic Safety Rules Storage Rules Chemical Storage Surveys General Storage Requirements Specific Storage Requirements Question and Answer Period Tips For Using Contractors

Why Hydrogen Sulfide Safety Is Important. The Basics of Toxicology as it Relates to Hydrogen

Sulfide. Basic Safety Precautions Related to Hydrogen Sulfide

Safety. Specific Hazards Associated with Hydrogen Sulfide

Exposure. The Training Requirements Associated with Hydrogen

Sulfide. Basic Storage Requirements as they Relate to Safety. The Use of Personal Protective Equipment to Prevent

Exposure.

Student learning outcomes

UNDERSTAND THE FOLLOWING:

All employers are legally obligated to provide for the health , safety and welfare of its’ employees.

Employers should provide information, instruction, training and supervision.

The General Duty Clause

Training requirements

The Hazards of Hydrogen Sulfide. The Use of Equipment. What PPE Is Necessary. When PPE Is Necessary. The Limitations of the PPE. Decontamination Procedures. Engineering Control Operation. Provide Retraining As Required. Care and Maintenance of Equipment. Classification of Hazardous Materials. Train All Employees Prior to Job Assignment.

JOBSAFETY

THE EMPLOYER MUST PROVIDE TRAINING :

Close-Call Event. New Hazard or Equipment. Change in Job Assignment. New Hazard Control Methods. Occupationally Related Injury. Failure in the Safety Procedures. Permissible Exposure Exceedance.

Reason to Doubt Employee Proficiency.

Retraining requirements

REQUIRED WHEN THERE IS A:

JOBSAFETY

Technical Hazard Data

HAZARD RATINGS AND TECHNICAL DATA

NOTE: Hazard Ratings Used in This Course May Differ From Chemicals Used at Your Facility Because of the Purity and Specific Mixture of the Chemical You Use.

Refer to Your SHOC/Material Safety Data Sheet for Specific Hazard Data for the Chemicals You Use.

Some Technical Hazard Data Used in This Course Are Derived From the NIOSH Guide To Chemical Hazards.

What is H2S ?

• Sulphuretted hydrogen, stink damp, sour crude, sour gas, marsh gas, rotten egg gas.

• Highly toxic / flammable gas.

• Found both onshore and offshore.

H2S

• A naturally occurring gas.

• Aerobic / anaerobic bacteria.

• Found in oil & gas, produced water, stagnant water, seawater.

• Mines, sewers, storage tanks and swamps.

H2S Atmospheres

Arise when H2S is released from:-

• Leaking valves.

• Leaking flanges or joints.

• Escape from vents.

• Disturbance of sludge.

• Stagnant seawater.

SYNONYMS AND TRADE NAMES:

Synonyms and Trade Names

Hydrogen Sulfide Sewer Gas Sulfuretted Hydrogen

HYDROGENSULFIDE

PHYSICAL DESCRIPTION:

Physical Properties

Colorless Gas Odor of Rotten Eggs

HYDROGENSULFIDE

Hydrogen Sulphide(H2S)

S HH

Physical Properties H2S

• Colourless.

• Odour of rotten eggs, at lower levels. Do not rely on smell).

• Irritating to eyes and lungs.

• Soluble in water and liquid hydrocarbons.

• Flammable - burns with blue flame.

• Highly corrosive to certain metals.

Hydrogen Sulfide - (H2S) Vapor Density: 1.19 Boiling Point: - 77.00 F. Color: Colorless Odor: Rotten Eggs Solubility in Water: 0.4% Range of Flammability: 4.0 - 44.0 %

SPECIFIC PROPERTIES:

Physical Properties

Measurements of H2S

• Flammable limits.

• Flash point.

• Ignition temperature.

• Vapour pressure.

• Vapour density.

• Parts per million.

RGasD - Relative density of gases as referenced to air = 1(How many times a gas is heavier than air at the same temperature)

VD GREATER than 1.0:The vapors are heavier than air and lay in low areas.

VD LESS than 1.0: The vapors are lighter than air and will rise.

VAPOR DENSITY (RGasD):

VAPOR DENSITY OF HYDROGEN SULFIDE IS: 1.19

Physical Properties(Continued)

Knowing whether a vapor will rise or fall in open air can give you valuable information to draw to ensure safety during a leak or spill situation.

VAPOR DENSITY IS IMPORTANT:

Physical Properties (Continued)

The point when vapor pressure equals atmospheric pressure liquid boils. The corresponding temperature is called the boiling point of liquid.

BOILING POINT:

BOILING POINT OF HYDROGEN SULFIDE IS: - 77.00° F

3

Physical Properties(Continued)

Sublimation is the process by which a solid substance changes into a gas, or vapor, without first becoming a liquid. These substances are said to sublime.

Physical Properties (Continue

d)

BOILING POINT IS IMPORTANT:

Knowing the boiling point lets you know when a liquid will transfer to a vapor, or begin to dangerously expand in enclosed containers.

Physical Properties(Continue

d)

The ability of a substance to dissolve in another is called its solubility.

Solubility depends on the chemical properties and temperature of the substances of the liquid solution.

For gases, solubility also depends on pressure.

SOLUBILITY:

SOLUBILITY OF HYDROGEN SULFIDE IS: 0.4%

Physical Properties (Continue

d)

Gases are soluble in liquids such as water.

We bubble air into a fish tank to allow breathing.

Fish breathe solubilized oxygen.

Carbon dioxide puts the “fizz” in carbonated beverages.

A soda left open in a warm room will get flat quickly.

All of these observations are dependent upon the solubility of gases in water.

SOLUBILITY OF GASES IN WATER:

Physical Properties(Continue

d)

SOLUBILITY IS IMPORTANT:

Knowing how soluble a liquid is lets you know to what degree the material will mix with other liquids in a spill situation.

It could mean the different between draining a million gallon collection pond or simply skimming the surface to remove a spilled substance.

Flammable Limits

• Lower explosive limit - (LEL) - is the lowest concentration of fuel in air which will burn.

• Upper explosive limit - (UEL) - is the maximum concentration of fuel in air which will burn.

FLAMMABLE RANGE:

Physical Properties(Continued)

The numerical difference between the upper and lower explosive limits. In other words the range that the vapors of a flammable liquid (when ignited) will burn when mixed with ambient air.

UEL / LEL - H2S

0% Volume

Flammable Range

100% Volume

46% UEL

4.3% LEL

Hydrogen Sulphide

Flammable Limits - H2S

0% Volume

100% LEL

100% Volume

46% Vol UEL

4.3% Vol LEL

Hydrogen Sulphide

Physical Properties(Continu

e)

UPPER FLAMMABLE LIMIT (UFL)

The “richer” point at which a mixture of flammable vapor and air will no longer support combustion

LOWER FLAMMABLE LIMIT (LFL)

The “leaner” point at which a mixture of flammable vapor and air will no longer support combustion

LFL to UFL = THE FLAMMABLE RANGE

Flammable Range

Gas LEL UEL

Hydrogen Sulphide 4.3% 46%

Pentane 1.4% 8%

Propane 2% 9%

Hydrogen 4% 80%

Methane 5% 15%

Acetylene 2% 82%

Flash Point

The lowest temperature at which a liquid gives off sufficient flammable vapour in air to produce

a flash on the application of a small flame.

Ignition Temperature

The lowest temperature to which a substance has to be raised for sustained

combustion to take place.

Vapour Pressure

The measure of a liquid’s volatility,

i.e. the readiness of a liquid to release vapour.

Vapour Density

The ratio of the weight of a given volume of a gas or vapour to the weight of an equal volume of another gas (normally air).

• Vapour density of air = 1

• Hydrogen sulphide = 1.19

• Hydrogen = 0.07

• Methane = 0.55

• Carbon Monoxide = 0.97

Strong Oxidizers Strong Nitric Acid Metals

INCOMPATIBLES AND REACTIVES:

Physical Properties(Continued)

IMDG/UN Labelling DOT Name: Hydrogen Sulphide DOT Hazard: Toxic Gas DOT Label: Toxic Gas, Flammable Gas DOT ID Number: UN1053 CAS Number: 7783-06-4

DOT/IMDG INFORMATION:

Physical Properties(Continued)

Physical Properties(Continue

d)

The pH of a Liquid Is the Numerical Measure of Its Relative Acidity or Alkalinity.

Range Is From 0 - 14 Neutral Level Expressed 7.0 Above 7.0 Liquid Is More Alkaline or Basic Below 7.0 Liquid Is More Acidic

pH INFORMATION:

ACID

NEUTRAL

BASE

12

11

10

9

8

7

6

5

4

3

2

Wine

LimewaterHousehold ammonia

Milk of magnesia

BloodPure Water

Tap Water

Coffee

VinegarLemon juiceGastric juice

Physical Properties(Continued

)

pH INFORMATION:

CHECK FOR COMPATIBILITY WITH EACH OTHER!

HIGH pHBASEACIDLOW pH

Physical Properties(Continued)

CHECK FOR COMPATIBILITY WITH YOU!

BASEACID

Physical Properties (Continued)

Hazard Rating Systems

EXAMPLE OF TWO SYSTEMS

NFPA - NATIONAL FIRE PROTECTION ASSOCIATION

HMIS - NATIONAL PAINT AND COATINGS ASSOCIATION

- HAZARDOUS MATERIAL IDENTIFICATION SYSTEM - CHIP 3

HMIS NFPA

4 SEVERE 4 EXTREME 3 SERIOUS 3 HIGH 2 MODERATE 2 MODERATE 1 SLIGHT 1 SLIGHT 0 MINIMAL 0 INSIGNIFICANT

FIVE HAZARD LEVELS

Hazard Rating Systems(Continued)

403

FIRE HAZARD

REACTIVITY

SPECIFIC HAZARD(WATER REACTIVE)

HEALTH HAZARD

FIVE NFPA HAZARD LEVELS

- 4 EXTREME - 3 HIGH - 2 MODERATE - 1 SLIGHT - 0 INSIGNIFICANT

Hazard Rating for Hydrogen Sulphide

Effects H2S (1)

Depends on-

• Duration

• Frequency

• Intensity

• Individual susceptibility

• Alcohol consumption

Effects H2S (2)

0.13 ppm - Minimal perceptible odour

4.60 ppm - Easily detectable moderate odour

10 ppm - Beginning of eye irritation

27 ppm - Strong, unpleasant odour

Effects H2S (3)

100 ppm - Coughing, eye irritation - lossof smell after 2 / 15 minutes

200 - 300 ppm - Sense of smell quickly lost,eye and respiratory tractinflammation after one hour

500 - 700 ppm - Loss of consciousness andpossible death 30 / 60

minutes

Effects H2S (4)

700 - 1,000 ppm - Rapid unconsciousness,cessation of respiration,

then death.

1,000 - 2,000 ppm - Unconsciousness at once with early cessation ofrespiration and death in afew minutes.

Exposure Limits (1)

EH40 gives two exposure limits.

• Occupational Exposure Standards (OES’s)

• Maximum Exposure Limits (MEL’s).

Employee Exposure Limits

5 ppm (twa)

UK:

20 ppm (c)

OSHA:

WE’LL DISCUSS MORE ABOUT EXPOSURE LIMITS LATER

HYDROGENSULFIDE

Exposure Limits (2) Example (UK)

• Long term exposure limit (LTEL)

—Is an 8 hour time weighted average value.

—For H2S this is 5 ppm - TLV

• Short term exposure limit (STEL)

—Is a 15 minute time weighted average

—For H2S this is 10 ppm.

Exposure Limits (PDO)

• Long term exposure limit (LTEL)- 10 ppm

• Short term exposure limit (STEL)- 15 ppm

Burning of eyes, nose, and throat. Dizziness. Coughing, Choking. Headache. Breathing difficulty.

COMMON SYMPTOMS OF HYDROGEN SULFIDE EXPOSURE:

(Continued)

Health Effects Of Hydrogen Sulphide Exposure

EMERGENCY ACTIONS IF LEAK IS DETECTED:

Stay out of leak area and avoid down wind areas.

Notify fellow employees in the area.

Call emergency response personnel.

Get to, and stay up wind.

Follow local emergency procedures.

FIRST AID

(Continued)

Health Effects Of Hydrogen Sulphide Exposure

EMERGENCY ACTIONS IF LEAK IS DETECTED:

Eye Contact:

Irrigate immediately for 15 minutes, seek medical help.

Ingestion/Inhalation:

Get to clean air, seek medical help.

Skin Contact:

Wash skin with soap and water for at least 15 minutes.

(Liquefied) Warm frost bite with warm water.

Seek medical help. FIRST AID

(Continued)

Health Effects Of Hydrogen Sulphide Exposure

LETS DISCUSS SOME OF THE TERMS THAT WILL BE HELPFUL IN UNDERSTANDING THE AFFECTS OF HYDROGEN SULFIDE ON YOUR BODY.

OCCUPATIONALTOXICOLOGY

Basics Of Toxicology

“ALL THINGS ARE POISONS, OR THERE IS NOTHING WITHOUT POISONOUS QUALITIES. IT IS ONLY THE DOSE WHICH MAKES A THING POISON.”

PARACELSUS(1493 - 1541)

(Continued)

Basics Of Toxicology

Ignitability Is Flammable or Combustible.

Reactivity Can React With Itself or Other Materials.

Corrosivity Can Deteriorate Another Substance.

Toxicity In Its Normal State Is Harmful to Living

Things.

(Continued)

Basics Of Toxicology

EXPOSURE TERMINOLOGY

Hazardous MaterialA Material That Falls Into One or More Of the Following Categories. Hazardous Materials Can Have One or Many Characteristics That Can Add to the Intensity of the Toxic Action of a Particular Solid, Liquid, or Gas.

The Type of Substance. The Amount (Dose) Absorbed. The Period of Time Over Which It Is Absorbed. The Susceptibility/Sensitivity of the Person Exposed.

EVERYTHING IS TOXIC;

IT ALL DEPENDS ON THE DOSE.

How Well the Body Accepts a Substance Depends on:

(Continued)

Basics Of Toxicology

THE PRIMARY ROUTE FOR HYDROGEN SULFIDE

INHALATION

ABSORPTION

(Continued)

Basics Of Toxicology

FOUR PRIMARY ROUTES INTO THE BODY

INHALATION

INGESTION

ABSORPTION

INJECTION

(Continued)

Basics Of Toxicology

Breathing and smoking causes us to inhale substances which enter the lungs. Substances inhaled into the lungs cause scarring of the lungs or are readily absorbed into the blood stream.

INHALATION INGESTION ABSORPTION INJECTION

INHALATION

(Continued)

Basics Of Toxicology

Swallowing a substance causes penetration into the blood stream via the stomach and small intestine.

INHALATION INGESTION ABSORPTION INJECTION

INGESTION

(Continued)

Basics Of Toxicology

Entering the body through the skin causes substances to enter the blood stream at a slower rate than by inhalation. However, the resulting entry and distribution within the body is the same.

INHALATION INGESTION ABSORPTION INJECTION

ABSORPTION

(Continued)

Basics Of Toxicology

Injection occurs when substances are forced through this skin. This can occur as a result of such means as compressed gas, or by having the skin abraded by a penetrating object.

INHALATION INGESTION ABSORPTION INJECTION

INJECTION

(Continued)

Basics Of Toxicology

(Continued)

Basics Of Toxicology

TLV - Threshold Limit Value: One of three categories of chemical exposure levels: TLV-TWA, TLV-STEL or TLV-C.

TLV-TWA: Threshold Limit Value Time-Weighted Average: The time weighted average concentration for a normal 8-hour workday and a 40 hour work week to which nearly all workers may be repeatedly exposed without adverse effect.

NOTE: TLV should be used as an exposure guide rather than an absolute. A physician has the final word.

(Continue

d)Basis Of Toxicology

TLV-STEL: Threshold Limit Value - Short Term Exposure Limit: A 15 minute time-weighted average exposure that should not be exceeded at any time during the work day.

TLV-C: Threshold Limit Value - Ceiling: The concentration that should not ever be exceeded, even instantaneously.

• RATE OF ENTRY.

• STATE OF HEALTH.

• AGE OF INDIVIDUAL.

• ROUTE OF EXPOSURE.

• PREVIOUS EXPOSURE LEVELS.

• WORKPLACE ENVIRONMENTAL FACTORS.

• INDIVIDUAL SUSCEPTIBILITY AND HEREDITY.

Factors Influencing Toxic Action

TOXICACTION

Exposure Terminology

Acute Exposure:

Usually Minutes, Hours or Several Days.

Chronic Exposure:

Regular Exposure Over Months, Years, or a Lifetime.

The Toxicity of the Chemical or Material Combined With the Susceptibility of the Individual, Determines Whether the Exposure Is Acute or Chronic.

(Continued)

Latent Exposure: An injury or disease that remains undeveloped until an incubation period has elapsed. The period of time could be hours, days, months or years.

Exposure Terminology

The Toxicity of the Chemical or Material Combined With the Susceptibility of the Individual Is a Key Factor.

Factors Affecting Exposure

The Amount Entering the Body. The Length of Time of Exposure. The Rate of Absorption Into the Blood. The Physical Nature of the Chemical. The Chemical Nature of the Chemical. The Age of the Individual. The Health of the Individual.

Methods of Compliance Include:

Implementation of a Written Program. Establishment of Best Work Practices. Establishment of Engineering Controls. Establishment of Administrative Controls. Regular Evaluation of Mechanical Safety Systems. Evaluation of Each Facility Where Hydrogen Sulfide is

Used. Use of Personal Protective Equipment As a Last

Resort. On-Going Review of the Programs Effectiveness.

Methods Of Compliance

GENERAL TYPES OF CONTROLS:

CONSISTS OF:

ENGINEERING CONTROLS:

Design and installation of new or modified safety control systems.

Detailed preventative maintenance programs for on site maintenance activities.

Proper placement of storage systems to reduce potential effects during emergencies.

Detection Systems.

(Continued)

Methods Of Compliance

Hydrogen Sulphide Fixed Detection

System

Areas where an accumulation of H2S is possible may be monitored by use of fixed detectors that react to H2S and give early warning of its presence.

However, these should not be relied on to prove the area is clear of an H2S hazard.

Hydrogen Sulphide Hand Held Detection

System

Atmospheric detection equipment working on the same principle as flammable gas detectors.

These are usually incorporated within multi meters in that it monitors for more than one contaminate. H2S, CO, O2 and Combustible.

ADMINISTRATIVE CONTROLS:

Assignment of Responsibility.

Support From Upper Management.

On-Site Safety Inspections and Audits.

Written Policies - Establishment of Site Safety Protocols.

Training - Job Specific Training Programs.

Checklists - Job Specific Safety Checklists, MSDS.

Placement of Warning Signs and Employee Information.

Methods Of Compliance(Continued)

Methods Of Compliance (continued)

GENERAL REQUIREMENTS:

Full body skin protection for potentially exposed workers.

Proper gloves to prevent hand exposure.

Adequate Eye and Face Protection.

Full body protection from extreme cold.

Means to Achieve Safety Compliance:

EXPOSURE INFORMATION:

(Continued)

Each job where hydrogen sulfide is used will have a written description of the specific means that will be employed to achieve compliance, including engineering plans and studies used to determine methods selected for controlling safety of hydrogen sulfide.

Ensuring employees are familiar with written safety policies.

Exposure Control

Effects on equipment

Corrosiveness

Hydrogen Sulphide is highly corrosive, especially in association with moisture or oxidizing gases such as Oxygen and Carbon Monoxide.

Iron and steel are particularly vulnerable.

Effects on equipment

Corrosion mechanisms associated with Hydrogen Sulphide include:

general corrosion

pitting

crevice corrosion, including Sulphide Stress Corrosion Cracking which can lead to sudden and catastrophic failure

Hydrogen induced cracking, also known as hydrogen embrittlement

Any equipment likely to be exposed to Hydrogen Sulphide must be made of appropriate materials, constructed and operated to take account of these corrosion problems.

Effects on equipment

Pyrophoric Scale

Carbon steel lines and equipment that carry gas or liquids containing hydrogen sulphide may develop a layer of pyrophoric scale (iron sulphide) on their internal surfaces.

When these lines or equipment are opened up to atmosphere, oxygen from the atmosphere will react with the pyrophoric scale to produce spontaneous burning.

If hydrocarbons or other combustible substances are present during this reaction, an explosion may result.

Warning: A by-product of this oxidising process is Sulphur Dioxide, which is also toxic.

Effects on equipment

Whenever such lines and equipment are opened up to atmosphere, their internal surfaces should be doused thoroughly with water or blanketed by steam in order that any pyrophoric scale is rendered harmless.

Warning: Equipment and pipework that has been on sour-gas duty should only be opened in one place at a time unless the pyrophoric scale has been thoroughly wetted.

Opening the system in more than one place can cause through drafts capable of igniting the scale.

Effects on equipment

If the introduction of water is not permissible, either due to corrosion potential or the risk of freezing, a nitrogen purge followed by a further purge with a mixture of 5% oxygen in nitrogen will allow controlled oxidation.

Pyrophoric scale that has been removed from lines and equipment shall be placed in a drum and immediately covered with water.

It must then be disposed of by:

Burying or burning in a suitable area as determined by legislation (onshore situations)

Slurrying with water and storing in sealed drums, clearly marked ‘PYROPHORIC SCALE’.

Harweel H2S Management Philosophy (PR1078)

H2S in the upstream oil and gas industry comes from:

The original reservoir, as a result of the hydrocarbon source material and the conditions under which it was converted to oil and gas.

If this is the case then H2S will be produced with the fluids

The reservoir after prolonged injection of water with oxygen (brackish or formation water) which may result in 'souring' of the fluids within it due to the action of sulphate reducing bacteria (SRB) introduced during the injection process.

Any H2S will be subsequently produced with fluids.

H2S level comparison

SWEET

LOW-RISK SOUR

HIGH-RISK SOUR

NATURAL H2SENRICHED GASACID GAS

PDO H2S SAFETY CRITERIA -500ppm

HARWEEL H2S LEVELS –50,000 – 200,000ppm

ppmH2S

1

10

100

1,000

10,000

100,000

1,000,000

SWEET

LOW-RISK SOUR

HIGH-RISK SOUR

NATURAL H2SENRICHED GASACID GAS

PDO H2S SAFETY CRITERIA -500ppm

HARWEEL H2S LEVELS –50,000 – 200,000ppm

ppmH2S

1

10

100

1,000

10,000

100,000

1,000,000

H2S Management

Project will be implementing novel and more stringent safety criteria for H2S management, in line with industry Best Practices.

Fit-for-purpose sour gas safety regime will reduce sour gas risks at Harweel.

To achieve this, expert advice on sour gas safety from Shell Canada and other agencies has been sought.

Key elements of H2S Management

Safety and Risk Management

Materials Selection

Instrumented Protective Functions (IPF) and Engineered Safeguarding

Emergency Response

Operations Competency and Training

Reliability and Maintenance.

Managing Simops.

Harweel H2S Management Philosophy (PR1078)

A facility shall be classed as being in sour service, with respect to personnel safety, when the gas phase of samples that have been reduced to atmospheric conditions contain 50ppm (v/v) or more of H2S. Periodic sampling and reassessment will be applied to maintain facility classifications up to date.

Sour service facilities shall be classified into three categories; Low Risk Sour, High Risk Sour and Very High Risk Sour.

The classification will be determined by assessment of the risk to personnel of an accidental release of process fluids, using gaseous dispersion calculations, and shall be agreed by Operations Asset Management

Harweel H2S philosophy

Facilities shall be designed and operated such that H2S exposure risk is reduced to as low as reasonably practicable (ALARP).

A means of detection of the presence of H2S shall be available to personnel in facilities classed as sour service.

Detection devices shall be set to give an alarm when the H2S concentration in air (ambient conditions) exceeds 10ppm.

Harweel H2S philosophy

Access to sour service facilities will be controlled, with entry to very high risk sour facilities, e.g. Harweel, Birba, Al Noor, governed by specific access restrictions.

Personnel entering a sour service facility shall be trained in H2S awareness and the appropriate action to be taken if released H2S is detected.

Respiratory protective (escape) equipment shall be available to personnel entering areas classified as High Risk Sour service facilities.

Hydrogen Sulphide (H2S) Management Procedure

The scope shall provide clear procedures to manage:

Location and control of sampling points

Risk Assessment

Facility H2S classification management

Sampling and frequencies

Personnel Training

Access Control

H2S Safety

Risk Assessment

The initial risk assessment for facilities that shall handle H2S is made during the concept, FEED and Detailed Design phase.

Equipment and systems shall be designed and use only materials suitable for use with H2S. Every effort shall be made to minimise the possibility of leaks to ‘as low as reasonably possible (ALARP).

Reference should be made to SP-1190 – Design of Sour Services Specification.

Process engineering shall also be responsible for ensuring that the correct Classification is applied based on the highest level of H2S expected to be present in the gas phase of the streams.

Risk Assessment

Future risk assessment shall be carried out as required if additions or modifications are made to the facility / plant or when the level of H2S present in the gas phase of the streams changes as indicated by sampling routines.

Facility H2S Classification Management

H2S Concentration (ppm) in the Gas Phase

Category

0 to 49 Sweet

50 to 499 Low Risk Sour

> 500 High Risk Sour (Further Assessment based on Quantitative Risk Assessment)

Very High Risk Sour (classification based on Quantitative Risk Assessment)

Risk Assessment

For ‘further assessment’ i.e. >500 ppm in gas stream the concentration at potential leak points is used to establish the correct category.

The assessment takes a distance of 2 meters from the potential leak point and calculates the H2S concentration in air.

If the calculations indicate the concentration to be < 200 ppm then the site will be categorised ‘low risk sour’; if above 200 ppm then the category shall be ‘high risk sour’.

This does not apply to Very High Risk Sour.

Personnel Training

All personnel who work in an H2S environment shall be adequately trained in how to deal with the hazards associated with H2S in accordance with the needs specific to their job and operate the safety equipment required to work in an environment containing H2S.

You have completed the You have completed the HYDROGEN SULPHIDE HYDROGEN SULPHIDE

SAFETY SAFETY Training CourseTraining Course

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