Presentation on theme: "There a lot of disasters due to failures. Some of them are as follows September 21, 1921: Oppau explosion in Germany. 4,500 tones of a mixture of ammonium."— Presentation transcript:
There a lot of disasters due to failures. Some of them are as follows September 21, 1921: Oppau explosion in Germany. 4,500 tones of a mixture of ammonium sulfate and ammonium nitrate fertilizer exploded killing 500–600 people and injuring about 2,000 more. 1932-1968: The Minamata disaster. Caused by the dumping of mercury compounds in Minamata. The Chisso Corporation, was found responsible for polluting the bay for 37 years. It is estimated that over 3,000 people suffered various deformities.
April 16, 1947: Texas City Disaster. At 9:15 AM an explosion occurred aboard a docked ship named the Grandcamp. The worst industrial disaster in America. 578 people lost their lives and another 3,500 were injured. The blast shattered windows from as far away as 25 mi (40 km).
March 28, 1979: Three Mile Island accident. Partial nuclear meltdown. Mechanical failures in the non-nuclear secondary system, followed by a stuck- open pilot-operated relief valve (PORV) in the primary system, allowed large amounts of reactor coolant to escape. Plant operators initially failed to recognize the loss of coolant, resulting in a partial meltdown. The reactor was brought under control but not before up to 481 PBq (13 million curies) of radioactive gases were released into the atmosphere.
December 3, 1984: The Bhopal disaster India the largest industrial disaster on record. A faulty tank containing poisonous methyl isocyanate leaked at a Union Carbide plant. About 20,000 people died and about 570,000 suffered bodily damage. The disaster caused the region's human and animal populations severe health problems to the present.
April 26, 1986: Chernobyl Nuclear Power Plant disaster, Ukraine, a test on reactor number four goes out of control, resulting in a nuclear meltdown. Killed up to 50 people Estimates up to 4,000 additional cancer deaths Approximately 600,000 most highly exposed people. The Chernobyl Exclusion Zone, covering portions of Belarus and Ukraine surrounding Prypiat, remains poisoned and mostly uninhabited. Prypiat itself was totally evacuated and remains as a ghost town.
July 6, 1988: Piper Alpha disaster. An explosion and resulting fire on a North Sea oil production platform kills 167 men. Total insured loss is about US$ 3.4 billion. To date it is rated as the world's worst offshore oil disaster in terms both of lives lost and impact to industry.
March 24, 1989: Exxon Valdez oil spill. The Exxon Valdez, an oil tanker hits Prince William Sound's Bligh Reef dumping an estimated 250,000 barrels of crude oil into the sea. It is considered to be one of the most devastating human-caused environmental disasters ever to occur in history. Overall reductions in population have been seen in various ocean animals. The effects of the spill continue to be felt 20 years later.
March 23, 2005: Texas City Refinery explosion. An explosion occurred at a British Petroleum refinery in Texas City, Texas, the third largest refinery in the US Processing 433,000 barrels of crude oil per day and accounting for 3% of that nation's gasoline supply. Over 100 were injured, and 15 were confirmed dead. Several level indicators failed, leading to overfilling of a knock out drum, and light hydrocarbons concentrated at ground level throughout the area. A nearby running diesel truck set off the explosion.
May, 29 2006, Mud Blow Out at Sidoardjo. Most of expert gathering at AAPG 2008 International Conference & Exhibition in Center, South Afrika, 26-29 Oct 2008 said that the cause was drilling by PT Lapindo Brantas More than 10000 home sank in the mud Mud blow out still active until now.
October 4, 2010: Alumina plant accident. Ajka, Kolontár, Devecser and several other settlements, Hungary. The dam of Magyar Aluminium Zrt.'s red mud reservoir broke and the escaping highly toxic and alkaline (~pH 13) sludge flooded several settlements. There were nine victims including a little girl and hundreds of injuries (mostly chemical burns).
ILO CONVENTION The General Conference of the International Labour Organization, having been convened at Geneva by the Governing Body of the International Labour Office, and having met in its 80th Session on 2 June 1993 Adopts the Convention, which may be cited as the Prevention of Major Industrial Accidents Convention, 1993.
SOME ARTICLE OF THE CONVENTION The purpose of this Convention is the prevention of major accidents involving hazardous substances and the limitation of the consequences of such accidents. each Member shall formulate, implement and periodically review a coherent national policy concerning the protection of workers, the public and the environment against the risk of major accidents. This policy shall be implemented through preventive and protective measures for major hazard installations and, where practicable, shall promote the use of the best available safety technologies.
ILO CONVENTION The competent authority, establish a system for the identification of major hazard installations, based on a list of hazardous substances or of categories of hazardous substances or of both, in accordance with national laws and regulations or international standards. And many more articles to be adhere by the member.
Safety and reliability have become essential parameters of automatic control system. Benefit of safe and reliable system include: o Less cost production o Higher product quality o Reduced maintenance cost o Lower risk cost How are the achieved? o High strength design o Fault tolerance design o On line failure diagnostic o Automatic control system
Safety and reliability are measured using a number of well defined parameters including: o Reliability o Availability o MTTF (Mean Time to Failure) o MTTR(Mean Time to Repair) o MTBF(Mean Time between Failure) o RRF (Risk Reduction Factor) o PFD (Probability of Failure on Demand) This terms has been developed over 50 years by safety engineering community
Basic Fundamentals of Safety Instrumented Systems SIS The operation of many industrial processes involve inherent risks due to the presence of dangerous material like gases and chemicals. Safety Instrumented Systems SIS are specifically designed to protect personnel, equipment and the environment by reducing the likelihood (frequency) or the impact severity of an identified emergency event.
PROTECTION LAYERS There are 6 protection layers should be used to confine accident as minimum as possible The first layer is Process Control layer consisting of Basic Process Control System (BPCS), and Safety Instrumented System (SIS) this layer controls the plant automatically The second layer is alarm system announcing that BPCS fails to control and operator should take action to override the control. The third layer is Emergency shutdown systems The 2 nd and 3 rd is the Safety Instrumented System
PROTECTION LAYERS The fourth layer is an active protection layer. This layer may have valves or rupture disks designed to provide a relief point that prevents a rupture, large spill or other uncontrolled release that can cause an explosion or fire.
PROTECTION LAYERS The fifth layer is a passive protection layer. It may consist of a dike or other passive barrier that serves to contain a fire or channel the energy of an explosion in a direction that minimizes the spread of damage. The final layer is plant and emergency response. If a large safety event occurs this layer responds in a way that minimizes ongoing damage, injury or loss of life. It may include evacuation plans, fire fighting, etc.
TSHH BPCS AND SIS process PIC 4-20 mA 3-15psi Set point I/P PT PSHH S S BPCS SIS ALARM
EMERGENCY SHUTDOWN AND LOGIC SYSTEM Emergency shutdown system is hardware & software system designed to shutdown a plant safely either automatically or manually, in case of emergency. Emergency Shutdown System (ESD) is designed to minimize the consequences of emergency situations, such as: uncontrolled flooding, escape of hazardous materials outbreak of fire Process out of control
Function of ESD Risk analyses has concluded that the Emergency Shutdown system is in need of a high Safety Integrity Level, typically SIL 2 or 3. Basically the system consist of field-mounted sensors, valves and trip relays, system logic for processing of incoming signals, alarm and HMI units. The system is able to process input signals and activating outputs in accordance with the Cause & Effect charts defined for the installation.
Basics of Safety Instrumented Systems SIS Typically, Safety Instrumented Systems consist of three elements: a Sensor, a Logic Solver and a Final Control Element
Sensors Field sensors are used to collect information necessary to determine if an emergency situation exists. The purpose of these sensors is to measure process parameters (e.g. temperature, pressure, flow, etc.) used to determine if the equipment or process is in a safe state. Sensor types range from simple pneumatic or electrical switches to Smart transmitters with on-board diagnostics. These sensors are dedicated to the Safety Instrumented System SIS.
Logic Solver The purpose of this component of Safety Instrumented Systems SIS is to determine what action is to be taken based on the information gathered. Highly reliable logic solvers are used which provide both fail-safe and fault-tolerant operation. It is typically a controller that reads signals from the sensors and executes pre-programmed actions to prevent a hazard by providing output to final control elements.
Final Control Element It implements the action determined by the logic system. This final control element is typically a pneumatically actuated On-Off valve operated by solenoid valves. It is imperative that all three elements of the SIS system function as designed in order to safely isolate the process plant in the event of an emergency.
Probability of Failure upon Demand PFD By understanding how components of an Safety Instrumented System SIS can fail, it is possible to calculate a Probability of Failure on Demand PFD. There are two basic ways for SIS to fail. a spurious trip covert or hidden failures
a spurious trip Spurious trip which usually results in an unplanned but safe process shutdown. While there is no danger associated with this type of SIS failure, the operational costs can be very high.
Covert or Hidden failures This failure does not cause a process shutdown or nuisance trip. The failure remains undetected, permitting continued process operation in an unsafe or dangerous manner. If an emergency demand occurred, the SIS would be unable to respond properly. These failures are contribute to the probability PFD of the system failing in a dangerous manner on demand.
PFD CALCULATION The PFD for the Safety Instrumented System SIS is a function of PFD's for each element of the system. In order to determine the PFD of each element, the analyst needs documented historic failure rate data for each element. This failure rate (dangerous) is used in conjunction with the Test Interval term to calculate the PFD.
STANDARD FOR SAFETY ISA 84.01 Standard IEC 61508 Standard IEC 61511 Standard
PURPOSE OF THE STANDARD to help individual industries develop supplemental standards, tailored specifically to those industries based on the original standard. to enable the development of of E/E/PE safety-related systems where specific application sector standards do not already exist. The bottom line is to help industries reach higher Safety Integrity level and reduce risk.
SAFETY INTEGRITY LEVEL SILPFDRRFTYPICAL APPLICATION 4<0.0001>10,000TRANSPORTATION, NUCLEAR 30.001- 0.0001 1000- 10,000 UTILITY BOILLER, OIL RIFENARY 20.01- 0.001 100-1000INDUSTRIAL BOILER, CHEMICAL PROCESS 10.1-0.0110-100Small industries having small risk
Safety life-cycle (SLC) SLC is an engineering process designed to optimize the design of the SIS and to increase safety. The concept of a safety life-cycle has been incorporated into many national and international standards, such as ANSI/ISA-84.00.01- 2004), IEC 61508 and IEC 61511. All of these standards have gained wide acceptance and are forming the basis for compliance with local, national and international laws and regulations.
THE THREE PHASES OF A COMPLETE SAFETY LIFE-CYCLE Analysis phase Realization phase Operation Phase
Analysis phase Identify and estimate potential hazards and risks. Evaluate if tolerable risk is within industry, corporate or regulatory standards. Check available layers of protection. If tolerable risk is still out of the limit, then allow use of a safety instrumented system (SIS) with an assigned safety integrity level (SIL). Document the above into the safety requirement specifications (SRS).
Realization phase Develop a conceptual design for technology, architecture, periodic test interval, reliability, safety evaluation. Develop a detailed design for installation planning, commissioning, start up acceptance testing, and design verification.
Operation Phase Installation, Commissioning and Validation Start-up review, operation and maintenance planning SIS start up, operation and maintenance, periodic functional test Modification Decommissioning
Benefits of the SLC provide an optimal SIS design Safer and more cost-effective designs risk will be reduced Proper selection of technology and correct specification of equipment