AUTHORISED GAS TESTER by Nigel Pitt: - Module 1
AUTHORISED GAS TESTING
AUTHORISED GAS TESTING by Nigel Nige l Pitt: - Module 1 Module Overview Purpose of this module
The purpose of this coaching module is to provide you with a brief background to the requirements of the Gas Testing procedure and the Confined Space Entry procedure. Provide the necessary understanding of the basics of hazard management of oxygen enriched / deficient, toxic and flammable gas atmospheres. Enhance your competency and ability to identify hazardous atmospheres and environments that may be Immediately Dangerous to Life and Health and determine the associated risks in the work place during pre-work site inspections. Understand the relevance of this and its application as required by the Gas Testing procedure PR1154, the Confines Space Entry procedure PR1148, Gas freeing, purging and leak testing procedure PR 1073, the H2S procedure PR1078 and the PTW system PR1172.
Learning outcomes and objectives
The aim of this module is to provide you with the necessary information and activities to enable you to:
Develop effective understanding of Gas testing by:
1.
Understanding the narcotic effects of hydrocarbons.
2.
Effective use of atmosphere / gas measuring and monitoring equipment.
3.
Gas testing in confined spaces,
4.
Gas testing for hot work.
5.
Interpreting and documenting the results of a gas test,
AUTHORISED GAS TESTING by Nigel Nige l Pitt: - Module 1 Module Overview Purpose of this module
The purpose of this coaching module is to provide you with a brief background to the requirements of the Gas Testing procedure and the Confined Space Entry procedure. Provide the necessary understanding of the basics of hazard management of oxygen enriched / deficient, toxic and flammable gas atmospheres. Enhance your competency and ability to identify hazardous atmospheres and environments that may be Immediately Dangerous to Life and Health and determine the associated risks in the work place during pre-work site inspections. Understand the relevance of this and its application as required by the Gas Testing procedure PR1154, the Confines Space Entry procedure PR1148, Gas freeing, purging and leak testing procedure PR 1073, the H2S procedure PR1078 and the PTW system PR1172.
Learning outcomes and objectives
The aim of this module is to provide you with the necessary information and activities to enable you to:
Develop effective understanding of Gas testing by:
1.
Understanding the narcotic effects of hydrocarbons.
2.
Effective use of atmosphere / gas measuring and monitoring equipment.
3.
Gas testing in confined spaces,
4.
Gas testing for hot work.
5.
Interpreting and documenting the results of a gas test,
AUTHORISED GAS TESTING by Nigel Nige l Pitt: - Module 1 Managing Health and Safety at a Corporate level
Any reputable organisation manages Health and Safety by the imposition of the requirements of an HSE management system on its employees and partners or stakeholders eg contractors etc. PDO is no exception. These management systems comprise primarily of; Policies Rules, Regulations, (i.e. statutory requirements) Standards Practices Procedures Specifications Guidelines and Codes of practice. The above essentially forms the ―system of work‖ which enables individuals to be guided in the correct manner regards the execution of any task or process management. The PDO HSE Management System as defined in CP 122 is structured as follows:
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 1. Overview of Hazard Identification Introduction
All Hazardous gas exposures within PDO operations need to be carefully identified and evaluated for potential health and safety exposures through a risk assessment and analysis process. There are several standards and assessment techniques to identify hazards. Examples of these process would include amongst others FMECA (Failure Modes and Effects Criticality Analysis) HAZOPS (Hazard Operability Studies) and HAZID (Hazard Identification) which can be used to establish a list of Hazards to be considered in any risk assessment process or review. It is important that the process is inclusive of all the significant hazards with a potential fatality consequence and not just the common hazards that are well kno wn and understood. This will include all probable cases where there is the potential for exposure to toxic, flammable gases or life threatening atmospheres. Employers in the PDO community have to ensure that a systematic and thorough examination of the work place is undertaken and the prevailing conditions and practices are identified, recorded and the significant findings evaluated to determine their risk potential. Furthermore, all contractors working for PDO are obliged in terms of PR1171 part II to identify hazards and manage associated risks.
PR 1171 part II
Section 2.6.2 Contract-Specific HSE Management Plan Contractor(s) shall, following the Contract Award, kick-off Meeting and on site HSE Workshop, revise its original HEMP and from that develop the Contract-Specific HSE Management Plan.
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Activity 2
Discuss the typical hazards associated with gas that are found in oil and gas exploration and production?
Gas Note
Gas is one of the four classical states of matter; the others being; liquid, solid & plasma. At near absolute zero, a substance exists as a solid. This is the lowest temperature that is theoretically possible, at which the motion of particles that constitutes heat would be minimal. It is ―zero‖ on the Kelvin scale, equivalent to –273.15°C or – 459.67°F. As heat is added to a substance it melts into a liquid; at its melting point, boils into a gas; at its boiling point, and if heated high enough would enter a plasma state; in which the electrons are so energized that they leave their parent atoms from within the gas. Solid, Liquid and Gas
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 4. A gas can diffuse into another gas. Reason: Molecules in a gas move very fast. Hence the rate of diffusion is very large. 5. A gas on cooling changes into liquid state. Reason: Cooling reduces intermolecular separation and increase intermolecular force of attraction. 6. A gas can flow in all directions. It requires a vessel closed from all sides to contain it
Source of Natural Gas
Natural gas is a made up of a mixture of hydrocarbons. The main hydrocarbon in natural gas is methane, but there are also small amounts of ethane, propane and butane. Natural gas originates from organic matter like plants and tiny sea creatures that lived millions of years ago. As the organic matter decayed it was covered with layers of silt and clay which over time turned into rock. Over millions of years, the heat of the earth and the pressure from the weight of rocks above transformed some of the organic matter into the fossil fuels coal, oil and natural gas. The movement of water, and pressures within the earth's crust, caused the oil and natural gas to move. Some of the oil and gas accumulated in traps or reservoirs (formed by porous rocks, covered by non-porous rocks) within the earth's crust.
Radon Gas
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Narcotic effects
Dose
What gases should we be concerned about in the oil and gas business?
The severity of effects of an inhaled toxin on a body depends on: i.
Concentration of toxin (ppm) in air
ii.
Duration of exposure (number of breaths)
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1
When should gas tests be conducted?
1.
Before work starts and
2.
During continuous work where there is the potential for exposure to a gas leak
Gas testing is mandatory prior to work being undertaken in a process or hydrocarbon area that carries a risk to personnel or equipment from exposure to explosive, flammable, toxic or life threatening vapours. Gas testing shall also be required in any other area where the above risks are considered to exist which are covered by the PDO Permit to Work (PR1172) or a 3rd Party compliant system. Why do we need to test for gas?
To ensure there are no toxic gases present in the work area and in the air and that the atmosphere is breathable To ensure the oxygen levels in the air are sufficient to support life To ensure there are no flammable or explosive gases present and so minimise the possibility of an explosion happening.
How does the human breathe?
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Any increase in the oxygen level above normal during confined space entry activities shall be invest igated, a Risk Assessment completed and appropriate measures taken. The most common oxygen containing equipment is that used in gas cutting operations. Cylinders, gas hoses, valves and welding torches shall be handled with care and should be daily inspected for damage. Gas cylinders shall not be taken into confined spaces unless the risks have been assessed and appropriate authorisation is obtained from the Responsible Supervisor. If allowed into the confined space all such equipment shall be removed during breaks and at the end of the working day. All O2 cylinder valves shall be closed when not in use.
Oxygen Depleted (deficient) Atmosphere
Atmospheres containing less that 20% vol. oxygen shall be treated as oxygen depleted (deficient) or hypoxic. Such atmospheres can occur when gas freeing or purging has been carried out to remove hydrocarbons / toxics or air. The oxygen in the atmosphere shall have been normally replaced / diluted with an inert gas i.e. nitrogen. Oxygen deficiency in an atmosphere can result in asphyxiation. A relatively small reduction in the oxygen level can lead to impaired mental ability and can provoke a feeling of euphoria or wellbeing leading to an overoptimistic judgment of the situation. The effects generally occur without alerting the senses. Loss of consciousness can occur without warning. This can happen even in circumstances where only a person‘s head is inside a confined space. Very low oxygen concentrations, below 10%, can lead to unconsciousness and death. Inhaling an atmosphere with no oxygen results in instant death. There is no panic or discomfort; death is swift and silent. Oxygen deficiency can result from:
i.
Displacement of air from low points in a confined space by heavier gases such as hydrocarbons or carbon dioxide;
ii.
Purging of the confined space with an inert gas to remove flammable or toxic gases, fumes, vapours or
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Flammable gas testing
Gas testing shall be carried out to detect accumulations of flammable vapours, fumes or dust in atmospheres which could ignite in the presence of a source of ignition. Flammable vapours or fumes typically result from: i.
Materials previously processed or stored in the vessel or tank;
ii.
Sludge or other deposits disturbed during cleaning;
iii.
Material left under scale, even after cleaning;
iv.
Material leaking through the tank floors;
v.
Material leaking from behind vessel linings (lagging, refractory etc.) or from vessel fittings such as tank floating roof pontoons and legs, instrument connections or pipes;
vi.
Materials leaking from flanges or vents on process pipes running through the confined space, e.g. process tubes in a furnace combustion chamber;
vii. Vapour entering the confined space from nearby process plant that has not been effectively isolated or from nearby work that is not well controlled; viii. Solvents brought into the space for cleaning, painting, dye penetration tests or in adhesives; ix.
Gases brought into the space / area for welding or gas cutting, including leakage from cylinders, valves and hoses;
x.
Contaminated firewater / process water used to wash the confined space and introduced by hoses;
xi.
Vapour or fumes that build up in sewers, manholes, contaminated ground or excavations.
A source of ignition can be any heat source having enough energy to ignite a flammable vapour air mixture, or to raise the temperature above the auto-ignition temperature. Possible ignition sources include: i.
Open flames and sparks resulting from welding, gas cutting and grinding;
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Toxic gas testing
Toxic gas testing shall be carried out to identify and detect toxic substances either in or adjacent to the confined spaces or other places of work. Substances can be solids, liquids or gases. Toxic vapours can cause injury, acute or long-latency illness, or death, depending on the characteristics of the substances, the concentration and the duration of exposure. For example, prolonged exposure to benzene can cause kidney damage or even leukaemia. Toxic hazards in confined spaces can result from the same sources as the flammable hazards. Common toxic substances in the oil and gas industry are: Acute toxic gases such as hydrogen sulphide, carbon monoxide, hydrogen fluoride, ammonia and chlorine; Hazardous liquids such as benzene, polycyclic aromatics, lead/anti-knock compounds, hydrazine and biocides; Narcotic gases and vapours such as butane, pentane, hexane, gasoline and gas condensate; Toxicity data for specific substances, e.g. Material Safety Data Sheets (MSDS) or Safe Handling Of Chemical Cards (SHOC), shall be required from the supplier of materials or from government authorities, and shall be made available on site. If these are not available then a competent industrial hygienist shall assess the toxicity of the intermediates and products. Crude oil and refinery process streams are mixtures of many hydrocarbons that individually have significant toxic or narcotic effects. The Health Risk Assessment (HRA), as input to the Job Hazard Analysis (JHA), shall assess the hazards of the mixture in the situation / areas where persons could be exposed. Specifically, the HRA should make a recommendation on whether flammability measurements are sufficient to detect harmful levels of the potentially toxic substance. Different criteria may be needed for: i.
Confirming that the atmosphere in the confined space is safe for entry, for planned work, and
ii.
Requiring persons to leave the space in case of an increased level during the work
Substances that are harmful by inhalation normally have an assigned Occupational Exposure Limit (OEL). An Action Limit of 50 % of the published OEL shall be applied as the trigger for implementing specific measures for controlling exposure to the toxic substance during the confined space work, but the target should be to reduce the airborne concentration to ALARP. OEL data may not be available for some toxic dusts, sludge and other
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 0-6% Hazardous area classification
Immediate coma, respiratory arrest, death
Zone 0: An area in which an explosive gas atmosphere is present continuously or for long periods; Zone 1: An area in which an explosive gas atmosphere is likely to occur during normal operation; Zone 2: An area in which an explosive gas atmosphere is not likely to occur under normal operations and, if it occurs, will only exist for a short period of time.
Methane UEL - LEL
Explosive limit
All combustible gases and vapours have an ―explosive limit‖ between which the gas or vapour, mixed with air, is capable of sustaining the spread of flame. These can be referred to as the explosive or flammable range or limit
H2S UEL and LEL
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 e m u l o v y b %
For most practical gas testing purposes it is the LEL which is significant. 100% of LEL for Methane means 5% by volume. 50% of LEL for Methane means 2.5% by volume The AGT is responsible for recording the percentage of LEL for the specific flammable gas being tested on the permit.
Activity 4
How many parts ppm of H2S are there in 25% lel How many parts ppm of H2S are there in 50% lel How many parts ppm of H2S are there in 100% lel
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Exposure to low levels of carbon monoxide can cause fatigue, chest pain, shortness of breath, memory loss, skin lesions, sweating, and flu-like symptoms. In the long term, exposure to low levels can cause heart disease and damage to the nervous system. Skin contact with liquid carbon monoxide in the workplace can cause frostbite. Carbon monoxide poisoning is caused by inhaling combustion fumes. When there's too much carbon monoxide in the air, your body replaces the oxygen in the haemoglobin of your red blood cells with carbon monoxide. This keeps life-sustaining oxygen from reaching your tissues and vital organs. The effects of CO exposure can vary greatly from person to person depending on age, overall health condition i.e. physiology of the individual subject and the concentration and length of exposure Various appliances fuelled by wood or gas produce carbon monoxide, including:
Car and truck engines Portable generators Furnaces Water heaters Cooking ranges Charcoal grills Fireplaces Fuel-burning space heaters
Wood-burning stoves
Normally the amount of carbon monoxide produced by these sources isn't cause for concern. But if appliances aren't kept in good working order or if they're used in a closed or partially closed space — such as using a charcoal grill indoors or running your car in a closed garage — the carbon monoxide can build to dangerous levels. Smoke inhalation during a fire also can cause carbon monoxide poisoning Normally the amount of carbon monoxide produced by these sources isn't cause for concern. But if appliances aren't kept in good working order or if they're used in a closed or partially closed space — such as using a charcoal
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Carbon Dioxide CO2
What is carbon dioxide? Carbon dioxide is a colourless, odourless gas that has a faint acid taste. It can also be a liquefied compressed gas or white flakes or cubes. In solid form, it is used as dry ice. Carbon dioxide can be found naturally in spring water and is released when volcanoes erupt and trees are cut down. When people breathe, they exhale carbon dioxide. Carbon dioxide is also produced by burning fossil fuels, such as coal, oil, gasoline, natural gas, and diesel fuel. The chemical formula for carbon dioxide is CO2. In the atmosphere, carbon dioxide is part of the global carbon cycle between the atmosphere, oceans, land, marine life, and mineral reservoirs. It is a ―greenhouse gas‖ because it absorbs heat in the atmosphere, sending some of the absorbed heat back to the surface of the earth and contributing to global warming. Carbon dioxide emissions represent about 80 percent of all greenhouse gas emissions in the United States. Sources of carbon dioxide emissions, which contribute to climate change, include fossil fuel burning, electricity generation, transportation vehicles, cement or lime manufacturing, waste burning, and natural gas flaring
How can carbon dioxide affect my health?
Carbon dioxide in its gaseous form is an asphyxiant, which cuts off the oxygen supply for breathing, especially in confined spaces. Exposure to concentrations of 10 percent or more of carbon dioxide can cause death, unconsciousness, or convulsions. Exposure may damage a developing foetus. Exposure to lower concentrations of carbon dioxide can cause hyperventilation, vision damage, lung congestion, central nervous system injury, abrupt muscle contractions, elevated blood pressure, and shortness of breath. Exposure can also cause dizziness, headache, sweating, fatigue, numbness and tingling of extremities, memory loss, nausea, vomiting, depression, confusion, skin and eye burns, and ringing in the ears. If your skin touches dry ice, you can get frostbite or blisters. You may be more affected by exposure to carbon dioxide if you have a cardiac, lung, or blood disease or condition.
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Sulphur Dioxide
What is sulphur dioxide? Sulphur dioxide is a colourless gas with a pungent and suffocating odour, similar to the smell from a struck match. It has an acidic taste and is a liquid when under pressure. Sulphur dioxide is formed when fuel containing sulphur, such as coal and oil, is burned. The chemical symbol for sulphur dioxide is SO2. Most sulphur dioxide in the air comes from the burning of coal and oil at electric power generation plants. Other sources of sulphur dioxide in the air are industrial facilities that use coal or oil, petroleum refineries, cement manufacturing, metal processing, paper pulp manufacturing, and copper smelting. Trains, large ships, and some diesel equipment burn high sulphur fuel, which releases sulphur dioxide into the air. It can also be released into the air by mother nature ie from volcanic eruptions.
How can sulphur dioxide affect my health?
Short-term exposure to high levels of sulphur dioxide in the air can be life-threatening by causing breathing difficulties and obstructing airways, especially for people with lung disease. Long-term exposure to persistent levels of sulphur dioxide can cause chronic bronchitis, emphysema, and respiratory illness. It can also aggravate existing heart disease. When sulphur dioxide reacts with other chemicals in the air to form tiny sulfate particles, these particles can gather in the lungs and cause increased respiratory problems and difficulty breathing. Long-term exposure to sulphate particles can cause respiratory disease and even premature death. Prolonged industrial exposure to sulphur dioxide may decrease fertility in men and women. Breathing sulphur dioxide can irritate the nose, throat, and lungs, and cause coughing and shortness of breath. Short-term exposure to sulphur dioxide can cause stomach pain, menstrual disorders, and watery eyes, inhibition of thyroid function, loss of smell, headache, nausea, vomiting, fever, convulsions, and dizziness.
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Hydrogen Sulphide
Hydrogen Sulphide (H2S) is an extremely dangerous substance and can cause fatalities if not managed correctly. H2S can be present in the gas and liquid streams within the PDO operations. H2S in the upstream oil and gas industry comes from: i.
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
ii.
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.
Why are oil and gas fields a safety concern?
Oil and gas fields are areas where oil and natural gas have accumulated under the land‘s surface. Oil and gas fields can also be offshore in lakes and oceans. Oil and gas exploration operations drill in these fields to extract oil and gas for sources of energy.
These operations pose many health, environmental, and safety concerns. Health concerns in oil and gas fields include air emissions of toxic chemicals, drilling waste, radioactive waste, and contaminated water produced by drilling operations. Oil and gas production can emit hazardous air pollutants, including benzene, toluene, and xylenes. These activities can emit carbon dioxide and methane, which are greenhouse gases that contribute to global warming and climate change. Operations at oil and gas fields can also emit nitrogen oxides, volatile organic compounds2, carbon monoxide, sulphur, and particulate matter.
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 potable coastal waters.
An estimated 35 percent of produced water requires disposal because it cannot be recycled. Past disposal practices and accidental releases of produced water could contaminate groundwater.
Health and safety concerns at oil and gas fields include possible exposure to hydrogen sulphide, a poisonous and flammable gas that occurs naturally in oil and gas. It is an extreme health hazard because it can be fatal or harmful if inhaled. Hydrogen sulphide occurs in many areas marked with warning signs, but can be present in unidentified spaces.
Other safety concerns at oil and gas fields are open waste pits, abandoned wells, drilling equipment, cleaning and pumping activities, fires, explosions, and confined spaces where gases can accumulate. A major environmental concern is natural gas flaring, which is th e process of burning off gas during oil production. Gas flaring emits millions of tons of carbon dioxide each year. Other environmental concerns are damage to land and habitat, leakage of drilling fluids, and fires. PDO have special procedures for managing H2S in the Southern fields of Al Noor, Birba and Harweel
Properties of H2S
Colourless
Highly toxic
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Nitrogen
Nitrogen Nitrogen is a common normally colourless, odourless, tasteless and mostly diatomic non-metal gas. It has five electrons in its outer shell, so it is trivalent in most compounds. Nitrogen in the environment Nitrogen constitutes 78 percent of Earth's atmosphere and is a constituent of all living tissues. Nitrogen is an essential element for life, because it is a constituent of DNA and, as such, is part of the genetic code. Nitrogen molecules occur mainly in air. In water and soils, nitrogen can be found in nitrates and nitrites. All of these substances are a part of the nitrogen cycle, and there are all interconnected. Humans have changed natural nitrate and nitrite proportions radically, mainly due to the application of nitratecontaining manures. Nitrogen is emitted extensively by industrial companies, increasing the nitrate and nitrite supplies in soil and water as a consequence of reactions that take place in the nitrogen cycle. Nitrate concentrations in drinking water will greatly increase due to this. Health Effects Nitrates and nitrites are known to cause several health effects. These are the most common effects: - Reactions with haemoglobin in blood, causing the oxygen carrying capacity of the blood to decrease (nitrite) - Decreased functioning of the thyroid gland (nitrate) - Vitamin A shortages (nitrate) - Fashioning of nitro amines, which are known as one of the most common causes of cancer (nitrates and nitrites
Properties of Nitrogen
78% of air Gases asphyxiate by displacing oxygen
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Health effects
The above table is for ref purposes only
Permitted exposure level (PEL)
PEL refers to the concentration of a toxic substance that is judged safe for a worker to be exposed to. -
Also known as WEL (Workplace Exposure Limit)
-
Also known as Threshold Limit Value (TLV)
Based on an average concentration measured over an 8 hour work day. (TWA ) Worker may be exposed for 8 hrs per day, 5 days per week for years without ill health effects. European and international safety laws limit the amount of a toxic substance that it is legal to expose a worker to. These limits are chosen to ensure that continued exposure over months and years will result in no harm and no discomfort. So, at 5 ppm ( the WEL for H2S gas ) the worker will not be coughing or suffer from stinging eyes or other discomfort. This is based on an average concentration over 8 hours. PEL‘s for many chemicals are listed in a document called EH40 available on the hse.gov.uk website
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1
Immediate Danger to Life and Health (IDLH)
This is the concentration level of a toxic substance at which it may cause harm or make self rescue difficult.
PTW
Refers PTW standards applicable to all gas testing requirements in PR 1148 and PR 1172
Activity 5
For example, H2S at 100 ppm causes eye irritation which may make it difficult for a worker without eye protection to see clearly while trying to escape a hazardous environment.
Establish the PTW and gas testing requirements for entry into a well cellar for maintenance of an annulus valve?
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Activity 6
Complete a TRIC for an activity with which you are familiar and explain through demonstrating how you would
Tool box talk (TRIC)
deliver this to the work crew on site. Dangerous/hazardous work: Any work which has the potential to cause harm to employees Critical Task: A task if not performed properly has the potential to produce major loss to people, property, process and/or environment Practice: A set of positive guidelines helpful to performing a specific type of work that may not always be done in a set way. Procedure: A step-by-step description of how to proceed, from start to finish, in performing a task properly to completion. Task: Segment of work which requires a set of specific and distinct actions for its completion. Examples include:
Performing the pre-use inspection on an overhead crane.
Setting up the wrapping machine for a pipeline joint.
Performing an emergency shut down on the preheat furnace.
Step: One segment of the total task where something happens to advance the work involved Activity 7
Complete a JHA
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Flow chart for critical task analysis
Critical Task Analysis
Overview: Critical task - a task which has the potential to produce major loss to people, property, process and/or environment when not performed properly
Identify Critical Tasks Responsible Person: Break each task down into a required sequence of steps
Note: Step - one segment of the total task where Form: (mouseover) something happens to advance the work involved. Critical task analysis worksheet Experience shows that many tasks will break down into ten to fifteen or twenty key steps Note: Every aspect of the task, including safety, quality and production, should be considered. Also consider losses to the area or environment where the task is being done and the possible long-term consequences of improper performance. Consider the following four subsystems: Note: - People Controls include such things as engineering - Property changes, work rotation, personal protective - Process equipment programs, etc. - Environment
Responsible Person: Pinpoint loss exposures Responsible Person: Conduct an improvement check Responsible Person: Develop controls to prevent a potential loss Develop procedure? Yes
Create New Document
No
Training required? Yes
Conduct Training Responsible Person / Employees: Implement the task End
No
QR: Critical task analysis Note 1: To conduct an improvement check, one need only ask the right questions and seek answers. - What is the purpose of this step? - Why is this step necessary? - How can it be done better? - Who is best qualified to do it? - When should it be done? There are seven major ways to make the improvements: Note: - Eliminate the task / step Use the following techniques: - Combine tasks / steps - Employee orientation - Rearrange the sequence of steps - Proper task instruction - Simplify the task - Planned task observation - Reduce the frequency - Personal contacts, coaching and tipping - Substitute material - Safety talks - Relocate the task - Skill training
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Standard References
PR1154 and PR1148
Gas Test
PR-1172 – Permit to Work System Section 3.5 shall be referenced to determine the frequency of gas testing and the
Requirements
specific work it is required for. In general gas testing is required for the following types of work;
Breaking containment
Hot work in a process or hydrocarbon area
Gas freeing and purging
Confined space entry / work within a confined space
Checking for suspected gas leaks
Providing clearance for work activities
Use of diesel engines in a process / hydrocarbon area
Vehicle entry to a process / hydrocarbon area
Breaking
Gas testing shall be required when containment is broken on any system containing hydrocarbon or toxic liquids /
Containment
solids / vapours. Appropriate PPE and safety equipment i.e. SCBA, masks, face visors etc, shall be worn as necessary. The type of gas tested for shall be indicated on the PTW by the Area Authority in addition to the frequency of testing. Types of gas can include one or all of the following;
Hydrocarbons
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Providing Clearance
Work activities in hazardous area shall require that the atmosphere at the work site and in the surrounding areas is
for Work Activities
safe before permission is given to carry out the work activity.
Use of Diesel Engines
The use of internal combustion engines (diesel driven) within a process or hydrocarbon area shall be subject to
in a Process /
authorisation and require gas testing in accordance with PR-1172 – Permit to Work System Section 3.5.
Hydrocarbon Area
Diesel driven plant i.e. mobile cranes, air compressors etc, shall be subject to continuous gas monitoring while in use. The units shall also be subject to a gas test prior to starting. The gas test shall primarily be to check for hydrocarbons.
Vehicle Entry to a
Vehicles shall only be allowed into a process area if covered by a PTW. A PTW is not required for a hazardous area
Process /
but gas testing is mandatory for both.
Hydrocarbon Area
Vehicles shall be subject to continuous gas monitoring while inside the area. The gas test shall be to check for an explosive or flammable atmosphere.
Testing Instruments
Gas testing shall only be carried out by authorised ‗gas testing‘ personnel who have completed the necessary training. These personnel shall be registered in PDO. Testing can be carried out using approved instruments. The following types are in use by PDO: - Multigas monitors (indication usually in % LEL or % Vol or ppm dependant on the gas being monitored)
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 Detector Tubes
Detector tubes are single ‗spot‘ check devices for detection of gases in the direct vicinity of where the sample is taken. Different detector tubes are provided for different gases, the selection of the detection tube being dependant on the gas being detected. A ‗fixed volume3‘ sample is drawn through the detector tube by a hand pump. The detector tubes are calibrated and the change in colour observed will indicate the concentration of the gas present. In PDO the typical gas sampled for using detector tubes is H2S and CO2.
Pre-User Checks
Before using a portable gas detector (with exception of detector tubes) the following shall be observed: i.
Ensure that the gas detector ‗test‘ is in date. Do not use a gas detector that is ‗out of test‘
ii.
Check the gas detector for signs of damage. If damaged record and report the nature of the damage and exchange the gas detector for one that is undamaged (if possible)
iii.
Before using the gas detector ensure the ‗battery‘ is fully charged
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 procedures can be developed to conduct the required work safely. Evaluation and interpretation of the gas measurement data, and development of the procedure, should be done by, or reviewed by technically qualified personnel based on a Risk Assessment. Verification Testing
The atmosphere of a permit space which may contain a hazardous atmosphere shall be tested, using the appropriate gas test equipment to evaluate conditions are safe, at the time of analysis, to commence the required work. Results of testing (i.e., actual concentration, etc.) shall be recorded on the Permit to Work (PTW). “Measurement
Duration of Testing
is by volume of the total atmosphere.”
Measurement of values for each atmospheric parameter should be made for at least the minimum response time of the test instrument specified by the manufacturer.
Testing Stratified
When monitoring for entries involving a descent into atmospheres that may be stratified, the atmospheric envelope
Atmospheres
shall be tested a distance of approximately 4 feet (1.22 m) in the direction of travel and to each side. If a sampling probe is used, the entrant's rate of progress should be slowed to accommodate the sampling speed and detector response.
Order of Testing
A test for oxygen is performed first because most combustible gas meters are oxygen dependent and will not provide reliable readings in an oxygen deficient atmosphere. Combustible gases are tested for next because the threat of fire or explosion is both immediate and more life threatening, in most cases, than exposure to toxic gases and vapours. If tests for toxic gases and vapours are necessary, they are performed last.
PPE
Respiratory protective equipment
Helmet
Gloves
Chemical Resistant Clothing
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1
Hazardous environments
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1
Working in Confined Spaces Potential Hazards Associated with Confined Space Entry
In preparing for confined space entry ensure the potential hazards associated with confined space entry are recognised. These hazards can be any or all of the following: Oxygen deficiency or enrichment Flammability (fire and / or explosion) Residual liquids, or solids and associated toxic or other noxious gases Chemical hazards Physical hazards Number of personnel working within the confined space and rescue access to them Restricted entry / exit Narcotic and anaesthetic effect of hydrocarbon gas and vapours Emergency rescue equipment and methods
Planning and Risk Assessment
The first priority is to consider if the work in the confined space can be limited or avoided. Alternatives may be: i.
Residues may be removed from the outside using water jetting or in place cleaning systems.
ii.
In some cases it may be possible to see inside without entering by using a boroscope.
iii.
Use of non-invasive inspection techniques
If the work is to be carried out in a confined space a risk assessment shall be completed covering all activities that will be carried out both inside and outside of the space. Personnel selected for confined space entry shall have the correct level of competence, experience and knowledge as indicated by the risk assessment. It will be necessary to include Vendors / 3rd parties or HSE professionals in this task.
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 The Permit Applicant
The Permit Applicant shall prepare a rescue plan as part of the Risk Assessment Process suitable for the agreed maximum number of personnel and covering each entry. This document should be reviewed and approved by the Responsible Supervisor. Some examples of possible inclusions to the rescue plan are: i.
Number of personnel required to provide effective rescue.
ii.
The equipment required for immediate use
iii.
Contingency plans for loss of communication
iv.
Safest route of access and egress with respect to casualty handling
v.
Removal of unnecessary obstacles, which will hinder rescue operations
The Permit Applicant must appoint a trained rescue team before work begins. For efficient functioning, a rescue team must consist of at least two persons. The Permit Applicant must be sure that the designated rescue team can be deployed quickly in an emergency and that they will be able to function effectively. If assistance is required this shall be provided by the Area Fire Service. The rescue team must be equipped with suitable personal protective equipment to enable them to function efficiently. Rescue plans covering the maximum permitted number of personnel will be agreed and practiced before any entry takes place. If it is not possible or practicable to perform training exercises before entry, it is the Permit Applicant responsibility to ensure all parties with responsibilities under this plan are competent in their roles. Show the Shah video
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 vi.
When a person is in a confined space a standby person shall be in attendance at all times and the responsible supervisor shall ensure that this person is authorised and fully briefed on the activity to be undertaken
vii. Additional hazards, including concurrent activities in the vicinity of, or within, the confined space are considered viii. When entry to a confined space is required using breathing apparatus, only those persons trained and deemed competent in the use of the breathing apparatus shall be allowed to enter the confined space ix. All personnel involved in the confined space entry shall made aware of the hazards CAUTION: Additional to the use of Portable Multi-Gas Testers confined spaces that have contained hydrocarbons shall be tested using a Photo-Ionization Detector (PID – e.g. Draeger tube) to confirm that Occupational Exposure Levels are complied with before an entry is made. This is particularly important for the very low exposure limits of the carcinogenic compounds such as Butane, Pentane and Benzene Gas Freeing and Flushing
Tanks, towers and vessels that have contained hydrocarbon or toxic materials shall require gas freeing and ventilation before entry4 can be made. Gas freeing shall be in accordance with PDO Procedures, PR-1073 - Gas Freeing, Purging & Leak Testing of Process Equipment (Excluding Tanks) and PR-1079 - Gas Freeing and Purging of Tanks Procedure. Once gas freed and drained5 the confined space can be opened and ventilated. This method may be employed where high concentrations of toxic gases are encountered. Flushing with water (produced if available) shall be used on pipework, tanks, towers and vessels to remove heavy hydrocarbon deposits before opening for cleaning and / or maintenance and repair.
Working Atmosphere
Gas testing of confined spaces shall only be carried out by an Authorised Gas Tester and shall be as specified on the PTW and recorded on the Confined Space Entry Certificate and the Additional Gas Test Record form (if required).
Oxygen
Confined spaces may only be entered when the atmosphere inside has been certified as having a safe oxygen
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 PR-1515 - Control of HSE Risks of Dealing with Mercury in PDO Facilities Internal temp and humidity
For entry to spaces like Waste Heat Recovery Units of gas turbines, additional hazards may exist. These hazards exist due to the operational service where the space has been subjected to high temperature. Hazards such as internal temperature, humidity and hot surfaces should be included in the risk assessment, and suitable controls put in place. These controls could for example, result in work duration being reduced accordingly.
Breathing apparatus
For entry in to a confined space without the use of breathing apparatus, tests may include but are not limited to: Oxygen (between 20%-21%) H2S shall be no greater than 1ppm Benzene shall be less than 1ppm, but preferably zero Hydrocarbons in air less than 2% LEL but preferably zero (see Table) <2% ≥2% and <10 unsustainable ≥ 10%
Entry allowed without BA or
atmosphere
Entry only with BA No entry allowed
CAUTION: If it is considered that, the breathable atmosphere cannot be guaranteed then entry shall be completed wearing breathing apparatus. Ventilation
Ventilation shall be employed to make the atmosphere inside of the confined space able to ‗support life‘. Where the atmosphere in the confined space is flammable or toxic, forced ventilation will be employed to extract and clean air be allowed to replace that extracted by natural circulation from a low point. WARNING: Outside air shall not be forced in to expel the flammable atmosphere as this may cause an explosive
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 SAFETY HARNESSES / LIFELINES Safety harnesses shall be provided for all persons working inside the confined space if the work involves scaffolding or ‗raised‘ platforms. Suitable ‗strong points‘ shall be made available if not already provided. Lifelines shall be used at all times by personnel inside the confined space. PORTABLE POWER TOOLS Where practical power tools used within confined spaces shall be ‗pneumatic‘. Use of electrically powered equipment shall be kept to a minimum and be in accordance with SP-1111 - Temporary Electrical Supplies for Construction & Maintenance Work. The preference shall also be made to adopt pneumatic lighting for confined spaces rather than those powered from electrical circuits. Confined Space Entry Process
The following process shall be followed or adapted when undertaking work which requires ‗entry into a confined space‘. The following Permits and Certificates are associated with Confined Space Entry: i.
Permit to Work (PTW)
ii.
Confined Space Entry
iii.
Mechanical Isolation
iv. Additional Gas Test Record v.
Electrical Isolation
The Permits and Certificates shall be completed, signed and attached to the PTW with a Job Safety Plan (including Risk Assessment) and all relevant drawings and documents. Refer page 16 of PR1148 for more detail
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1 shall be used to continuously monitor the atmosphere. Liquid nitrogen, released into the atmosphere in an uncontrolled manner, will quickly change form to a gas, thus producing an asphyxiation hazard from the nitrogen-enriched atmosphere.
Precautions Prior to using nitrogen in either a gaseous or cryogenic form, an assessment of the risks to both personnel and equipment, from leaks or spills, shall be carried out. Particular attention should be paid to:
Provision of drain paths for spills and leaks.
Routes for temporary hoses.
Provision of First Aid equipment and competent persons to use it.
Written procedures for the operation, including emergency procedures for dealing with spills and leaks.
All work involving the use of nitrogen shall be controlled by the Permit to Work (PTW) Syste m. Barriers and warning notices shall be erected around the work area. All openings, man ways, pipe ends etc. must be clearly marked, and oxygen monitoring and rescue equipment provided. All personnel involved in the operation shall be instructed in the hazards associated with nitrogen operations and the types and functions of monitoring equipment being used. Where habitats or partial enclosures are required, these shall be treated as Confined Spaces, and the controls and precautions associated with Confined Space entry shall be applied.
AUTHORISED GAS TESTING by Nigel Pitt: - Module 1
Notes
