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Safety, refin. chapt.5

Safety, refin. chapt.5






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    Safety, refin. chapt.5 Safety, refin. chapt.5 Presentation Transcript

    • Chapter 5 Process Safety Prof. Dr. Ahmed A. S. Seifelnassr
    • Introduction Process safety programs should be implemented, due to industry-specific characteristics, including complex chemical reactions, use of hazardous materials (e.g. toxic, reactive, flammable or explosive compounds), and multi-step reactions.
    • Process safety management includes the following actions: 1- Physical hazard testing of materials and reactions; 2-Hazard analysis studies to review the process chemistry and engineering practices, including thermodynamics and kinetics; 3- Examination of preventive maintenance and mechanical integrity of the process equipment and utilities; 4- Worker training; and 5- Development of operating instructions and emergency response procedures.
    • 1- Machinery • All equipment should have safety guarding and workers should be issued with appropriate personal protective equipment to protect them and to avoid sharp items and edges and avoid workers becoming trapped and/or injured.
    • Mechanical Hazards MACINERY HAZARDS: These are due to revolving parts of the machines. These can be controlled by providing machine guards which are a statutory requirements . Provide guards at following; – Moving parts of the machinery including fly wheels – Transmission machinery – Point of operation – Any other dangerous part
    • Mechanical Hazard PREVENTION 1- Preventive maintenance 2- Adequate job training 3- Ensuring safe working environments 4- Establishment of safety department with qualified safety engineer 5- Periodic survey for finding out hazards 6- Application of ergonomics
    • • Application of ergonomics • Maintenance of temperature- 24 to 28 deg. C is the comfortable zone • Proper ventilation • Good housekeeping • Proper illumination • Personal protection • Personal hygiene • Health education • Job rotation • Periodic health Check up
    • SAFETY OF MAINTENANCE PERSONNEL • Safety precautions are required to safe guard the maintenance personnel from getting involved in machinery accidents owing to inadvertent starting of machinery by; • Design of control switches • Safe guards for the operating levers • Interlocking of power system
    • 2-Noise and Vibration and Odour The principal noise sources are: Heavy rotating machinery such as turbines, pumps, compressors, motors; Pressure release through flaring or steam valves; Coolers and furnaces; Truck movements. Odour Emissions of VOCs and sulphur compounds can cause odor problems at the site and in the surrounding area.
    • NOISE Threshold Limit Value for noisy working conditions: (An 8 hour shift in all following cases) • • • • • 8 hours work – 90 dBA 4 hours working – 95 dBA 2 hours working – 100 dBA 1 hour working – 105 dBA half hour work – 110 dBA • Threshold of hearing – 125 dBA • Sudden deafness/rupture of ear drum can occur at 140 dBA
    • Noise can be controlled by; 1. Reducing vibrations 2. Enclosing the noise producing equipment 3. Enclosing the operator 4. Moving away from the noisy area 5. Use of personal protective equipments
    • VIBRATION Vibration especially in the frequency of 10 to 500 Hz, can affect hand and arm after month of years of exposure Effects: • The fine blood vessel of finger becomes increasingly sensitive to spasm (white fingers). • Injuries of the joints, of the hands elbow and shoulders may take place
    • VIBRATION can be controlled by: • Continuous working should be avoided and rest pauses after some time of work must be allowed to workers. • The driving force of vibrating surfaces may be reduced by; – 1. Reducing the forces – 2. Minimizing rotational speed – 3. Isolating • The response of vibrating surfaces may be reduced by – 1. Damping – 2. Increasing mass of vibrating surfaces – 3. Changing size to change resonance frequency
    • 3- Burns and heat stress Working at high temperatures can increase the temperature of the working environment which can lead to heat stress for those working in the vicinity. Contact burns can result from contact with hot equipment especially during maintenance activities.
    • Effective temperature and heat effect in an environment can be controlled by: • Increasing air changes • Reducing radiated heat by insulation • Reflection of heat • Drinking plenty of water and intake of salt • Use of personal protective equipments
    • • 4- Confined Spaces • Confined spaces at refineries typically include storage tanks, secondary containment areas and wastewater management infrastructure. Such spaces are dangerous and entry to them must be strictly controlled and avoided wherever possible. The health and safety system should control access to confined spaces via what is termed a permit to work system (which is an internal control process operated by companies rather than an external authorization). Workers entering storage tanks for cleaning and inspection purposes must be provided with appropriate personal protective and respiratory equipment
    • What is a Confined Space? A space that: • Is large enough and so configured that an employee can enter bodily and perform work; • Has limited or restricted means of entry or exit; • Is not designed for continuous human occupancy. 17
    • Examples of Confined Spaces • • • • • • • Tanks Manholes Boilers Furnaces Sewers Silos Hoppers • • • • • • • Vaults Pipes Trenches Tunnels Ducts Bins Pits 18
    • Potential Hazards in Confined Spaces • Oxygen Deficiency – <19.5% or >23.5% oxygen concentration • Combustibles – – – – – Methane Hydrogen Acetylene Propane Gasoline fumes • Toxic Materials – – – – Carbon Monoxide Hydrogen Sulfide Welding fumes Corrosives • Electricity • Mechanical Hazards – Mixers – Crushers 19
    • Hazards of Confined Spaces • Oxygen Deficient Atmospheres • Oxygen Enriched Atmospheres • Flammable Atmospheres • Toxic Atmospheres • Temperature Extremes • Engulfment Hazards • Noise, Slick/Wet Surfaces, Falling Objects 20
    • Oxygen Deficient Atmospheres 19.5 % 15 - 19% 12-14% 10-12% 8-10% 6-8% 4-6% Minimum acceptable oxygen level. Decreased ability to work strenuously. Impair coordination. Early symptoms. Respiration increases. Poor judgment. Respiration increases. Lips blue. Mental failure. Fainting. Nausea Unconsciousness. Vomiting. 8 minutes - fatal, 6 minutes - 50% fatal 4-5 minutes - possible recovery. Coma in 40 seconds. Death 21
    • Oxygen Enriched Atmospheres • Oxygen level above 21%. • Causes flammable and combustible • • • • materials to burn violently when ignited. Hair, clothing, materials, etc. Oil soaked clothing and materials. Never use pure oxygen to ventilate. Never store or place compressed tanks in a confined space. 22
    • Flammable Atmospheres • 2 Critical Factors: – Oxygen content in the air. – Presence of a flammable gas, or vapor – Presence of dust • Proper air/gas mixture can lead to explosion • Typical Ignition Sources: – Sparking or electric tool. – Welding / cutting operations. – Smoking 23
    • Toxic Atmospheres • Product stored in a confined space: • Gases released when cleaning. • Materials absorbed into walls of confined space. • Decomposition of materials in the confined space. • Work performed in a confined space: • Welding, cutting, brazing, soldering. • Painting, scraping, sanding, degreasing. • Sealing, bonding, melting. • Areas adjacent to a confined space. 24
    • Hydrogen Sulfide • Decomposition of materials. Human waste. • Rotten egg odor at low concentrations. • Possibly no warning at high concentrations. PPM Effect 10 ppm 50 - 100 200 - 300 500 -700 >1000 Permissible Exposure Level Mild Irritation - eyes, throat Significant Irritation Unconsciousness, Death Unconsciousness, Death Time 8 Hours 1 Hour 1 Hour 1/2 - 1 Hour Minutes 25
    • Carbon Monoxide • Odorless, Colorless Gas. • Combustion By-Product. • Quickly collapse at high concentrations. PPM Effect 50 200 600 1000-2000 1000-2000 1000-2000 2000-2500 Permissible Exposure Level Slight headache, discomfort Headache, discomfort Confusion, nausea, headache Tendency to stagger Slight heart palpitation Unconsciousness Time 8 Hours 3 Hours 1 Hour 2 Hours 1 1/2 Hours 30 Min. 30 Min. 26
    • Other Hazards • Noise • Amplified due to acoustics within the space. • Damaged hearing, affect communication. • Slick / Wet Surfaces • Slips and falls. • Increased chance of electric shock. • Falling Objects • Topside openings expose workers inside confined space to falling objects. 27
    • Test the Atmosphere In this order: • Check for Oxygen Content: – At least 19.5% and less than 23.5% • Check for Combustibles: – Less than 10% of the LEL • Check for Toxic Gasses: – Most commonly carbon monoxide (PEL <35 ppm) – or any other hazardous materials as determined by the use of the space. 28
    • 29
    • Ventilation • First option to correct problems. • Must be aware of hazards you are trying to • • • correct in the confined space. Air intake in a safe location to draw fresh air only. Continuous ventilation whenever possible. Retest the confined space before entry. 30
    • Permit-Required Confined Space • A Permit-Required Confined Space is confined space that has one or more of the following characteristics: • Contains or has the potential to contain a hazardous atmosphere; • Contains a material that has the potential for engulfing an entrant; • Has an internal configuration such that an entrant could become trapped or asphyxiated; or • Contains any other serious safety or health hazard. 31
    • Non-Permit Confined Space • A confined space that does not contain or, with respect to atmospheric hazards, have the potential to contain any hazard capable of causing death of serious physical harm. 32
    • Permit-Required Confined Space Entry Procedure • • • • • • Isolate the space Ventilate the space Conduct tailboard Complete permit Test the atmosphere Enter the space 33
    • Isolate the Space from all hazards • Close Valves – Double block & bleed, or – Blank flange • Empty the Space – Depressurize, vent & drain • Lockout/Tagout Equipment – Electrical sources – Rotating/reciprocating parts – Hazardous materials • Clean residue from the space 34
    • Conduct a Tailboard Briefing • Entire crew must attend – Attendants, entrants, entry supervisor • Review hazards of entry and work • Review PPE • Review procedure for contacting rescue – verify rescue available • Complete permit 35
    • Complete Entry Permit Form • Permit must be correctly and completely filled out prior to entry. • Permit must be activated by Entry Supervisor’s signature to be valid. • No entry is allowed without a valid permit. • Permits are valid for up to 12 hours. • When work is completed, permit and tailboard form should be returned to safety. • Cancelled permits must be kept on file for at least one year. 36
    • Test the Atmosphere In this order: • Check for Oxygen Content: – At least 19.5% and less than 23.5% • Check for Combustibles: – Less than 10% of the LEL • Check for Toxic Gasses: – Most commonly carbon monoxide (PEL <35 ppm) – or any other hazardous materials as determined by the use of the space. 37
    • NOTICE: • Any time a limit is exceeded, no matter what the reason, all personnel shall immediately exit the space, and no others shall enter until atmospheric conditions are returned to safe levels. THERE ARE NO EXCEPTIONS TO THIS! 38
    • Atmosphere Testing Shall Be Performed: • Prior to every entry when the space is vacant; • After a 10 minute ventilation period (if ventilation is necessary); • At least hourly for permit-required confined spaces. • More frequently, if conditions or suspicions warrant. 39
    • Always test the air at various levels to be sure that the entire space is safe. Good Air Good air near the opening does NOT mean there is good air at the bottom! Poor Air Deadly Air 40
    • Enter the Space and Proceed with work: • An attendant shall be posted near the entrance for the duration of the work. He shall be in constant communication with the entrants while the job is in progress. • All entrants shall sign the sign in log when entering the space and sign out when exiting. • The attendant shall maintain the permit and sign in log for the duration of the work. 41
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    • When the Job is Done: • Remove all personnel, tools, and debris from the space. Sign off the log. • Close the space. • Cancel the permit. • Review the job with the host employer (hazards, problems, other employers, etc.) 45
    • Entrant Responsibilities • To assure that the space has been adequately ventilated, isolated, emptied, or otherwise made safe for entry. • To immediately exit a space, without question, upon word of the attendant, no matter what the reason. • To follow all safety rules and procedures that apply to the job. • To be familiar with the work to be performed and the procedures that apply to the job. • To use the appropriate PPE whenever necessary. 46
    • Supervisor Responsibilities • To assure adequate protection is provided to the entrants by verifying adequate lockout/tagout and that all hazards are securely isolated. • To support the attendant’s authority in controlling access to a confined space. • To verify that all personnel have exited prior to closing the space. • To assure that all personnel involved are aware of the hazards associated with the space. • To assure that rescue services are available prior to entry. 47