Process system valve requirement and safety design
Prakash Thapa (TA-1)
Open to right opportunity in any Industry around the world
What are the 14 elements of process safety management?
Elements of Process Safety Management
· Process Safety Information
· Process Hazard Analysis
· Operating Procedures
· Training
· Contractors
· Mechanical Integrity
· Hot Work
· Management of Change
· Incident Investigation
· Compliance Audits
· Trade Secrets
· Employee Participation
· Emergency Planning and Response
What is a pneumatic control valve?
Air control valves are fundamental components of any pneumatic system. Selecting the right air control valves to regulate system pressure, direction of flow, and rate of flow is crucial when designing fluid power circuitry. If the pneumatic valve is too big for your application, you will be wasting air and money.
What is a blowdown process?
Boiler blowdown is the removal of water from a boiler. Its purpose is to control boiler water parameters within prescribed limits to minimize scale, corrosion, carryover, and other specific problems. Blowdown is also used to remove suspended solids present in the system.
How does a pilot operated solenoid valve work?
The upper chamber is connected to upstream through a pilot hole in either the cover or diaphragm. The media exerts a pressure that acts on the upper side of the diaphragm and keeps the valve closed. When the coil is charged the core lifts off the orifice seat allowing the operating chamber to de-pressurise.
What is a MOV valve?
An MOV is a combination of two separate devices, usually provided by two separate manufacturers. – Valve Assembly. a mechanical device to optimize a desired fluid control function, such as isolation or throttling. – Actuator. an electrical/mechanical device used to position a valve assembly from a remote location.
Why there are 2 safety valve in the boiler?
Usually for High pressure Boiler , on its steam drum , two safety valves are placed. But of different pressure setting. Suppose the working pressure is 60 kg/cm2, then one safety valve will be set at around 65 kg/cm2 and the other one at 67.5 kg/cm2.
How does a safety valve work?
Safety Valve is a one type of valve that automatically actuates when the pressure of inlet side of the valve increases to a predetermined pressure, to open the valve disc and discharge the fluid ( steam or gas ) ; and when the pressure decreases to the prescribed value, to close the valve disc again.
How does a hydraulic pressure relief valve work?
Pressure relief valves are used in hydraulic systems to limit the system pressureto a specific set level. If this set level is reached, the pressure relief valve responds and feeds the excess flow from the system back to the tank. Note: the pressure relief valve is a normally closed pressure control valve.
What is a steam boiler used for?
The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, or natural gas. Nuclear fission is also used as a heat source for generating steam. Heat recovery steam generators (HRSGs) use the heat rejected from other processes such as gas turbines.
What is boiler and types of boiler?
There are two general types of boilers: ''fire-tube'' and ''water-tube''. Boilers are classified as "high-pressure" or "low-pressure" and "steam boiler" or "hot water boiler." Boilers that operate higher than 15 psig are called "high-pressure" boilers. A hot water boiler, strictly speaking, is not a boiler.
What is the difference between a safety valve and a relief valve?
Relief Valve–is the term used to describe relief device on a filled vessel. For such avalve the opening is proportional to increase in the vessel pressure. ... When the set pressure of the valve is reached, the valve opens almost fully. The difference is generally in capacity and setpoint.
Why Rankine cycle is used in thermal power plant?
The Rankine cycle closely describes the process by which steam-operated heat engines commonly found in thermal power generation plants generate power. ... The heat sources used in these power plants are usually nuclear fission or the combustion of fossil fuels such as coal, natural gas, and oil.
What is the use of condenser in thermal power plant?
In thermal power plants, the purpose of a surface condenser is to condense the exhaust steam from a steam turbine to obtain maximum efficiency, and also to convert the turbine exhaust steam into pure water (referred to as steam condensate) so that it may be reused in the steam generator or boiler as boiler feed water.
What is a blowdown drum?
Blowdown Drum. Share. A separate collection vessel intended to receive a periodic or emergency discharge of liquids, liquid reaction mass, or slurries from a number of process vessels, reactors, or equipment items. ... Blowdown drums are usually maintained at a low level or essentially empty.
What is supercritical steam?
A supercritical steam generator is a type of boiler that operates at supercriticalpressure, frequently used in the production of electric power. In contrast to a subcritical boiler in which bubbles can form, a supercritical steam generator operates at pressures above the critical pressure – 3,200 psi or 22 MPa.
What is the critical temperature of water?
At the triple point, all three phases can coexist. However, the liquid-vapor boundary terminates in an endpoint at some critical temperature Tc and critical pressure pc. This is the critical point. In water, the critical point occurs at around 647 K (374 °C; 705 °F) and 22.064 MPa (3200 psia or 218 atm).
How often do you need to carry out a risk assessment?
The Health and Safety Executive (HSE) says risk should be assessed "every time there are new machines, substances and procedures, which could lead to new hazards." An employer should carry out a risk assessment: whenever a new job brings in significant new hazards.
What are the five steps of a risk assessment?
The Health and Safety Executive's Five steps to risk assessment.
Step 1: Identify the hazards.
Step 2: Decide who might be harmed and how.
Step 3: Evaluate the risks and decide on precautions.
Step 4: Record your findings and implement them.
Step 5: Review your risk assessment and update if. necessary.
How do you complete a risk assessment?
Step 1: Identify the hazards. In order to identify hazards you need to understand the difference between a 'hazard' and 'risk'. ...
Step 2: Decide who might be harmed and how. ...
Step 3: Evaluate the risks and decide on control measures. ...
Step 4: Record your findings. ...
Step 5: Review your assessment and update as and when necessary.
Why is it important to do a risk assessment?
Risk assessments are very important as they form an integral part of an occupational health and safety management plan. They help to: Create awareness of hazards and risk. Identify who may be at risk (e.g., employees, cleaners, visitors, contractors, the public, etc.).
What is a quantitative risk?
Quantitative Risk Analysis. A quantitative risk analysis is a further analysis of the highest priority risks during a which a numerical or quantitative rating is assigned in order to develop a probabilistic analysis of the project.
What is a qualitative risk analysis?
Qualitative risk analysis is a project management technique concerned with discovering the probability of a risk event occurring and the impact the risk will have if it does occur. All risks have both probability and impact.
What is the fault tree analysis?
Fault tree analysis (FTA) is a top down, deductive failure analysis in which an undesired state of a system is analyzed using Boolean logic to combine a series of lower-level events
What is a bow tie analysis?
The Bowtie method is a risk evaluation method that can be used to analyse and demonstrate causal relationships in high risk scenarios. The method takes its name from the shape of the diagram that you create, which looks like a men'sbowtie.
What is an event tree?
Event tree is an inductive analytical diagram in which an event is analyzed using Boolean logic to examine a chronological series of subsequent events or consequences. For example, event tree analysis is a major component of nuclear reactor safety engineering.
What is a reliability block diagram?
Reliability block diagram. ... A reliability block diagram (RBD) is a diagrammatic method for showing how component reliability contributes to the success or failure of a complex system. RBD is also known as a dependence diagram (DD).
What is meant by hazcon?
The ABB HAZCON process is a systematic and formal method of identifying and assessing the risks which may be present during construction, maintenance, modification and demolition of an asset. ... Risk assessment at the early stages of a project can help minimise risks during construction and through the life of the asset.
What is risk assessment in a project?
The project risk management plan addresses the process behind risk management and the risk assessment meeting allows the project team to identify, categorize, prioritize, and mitigate or avoid these risks ahead of time. Risk assessment is a step in a risk management procedure. Risk assessment is the determination of.
What is a rating of a risk?
Rating a Risk. ... You can do what is called a Qualitative Risk Rating which means you can simply decide whether the risk is minimal, low, medium or high. Generally this short hand form of risk rating is used to determine which hazard should take priority over another in terms of deciding what to do and when.
What is a safety instrumented function?
SIF stands for Safety Instrumented Function. A SIF is designed to prevent or mitigate a hazardous event by taking a process to a tolerable risk level. A SIF is composed of a combination of logic solver(s), sensor(s), and final element(s).
What is a safety instrumented system?
A safety instrumented system (SIS) consists of an engineered set of hardware and software controls which are especially used on critical process systems.
What is safety integrity level?
Safety integrity level (SIL) is defined as a relative level of risk-reduction provided by a safety function, or to specify a target level of risk reduction. In simple terms, SIL is a measurement of performance required for a safety instrumented function (SIF).
What is the SIS system?
A student information system (SIS), student management system, school administration software or student administration system is a management information system for education establishments to manage student data.
What are the four pillars of SMS?
The four components of a SMS are:
· Establishes management commitment to safety performance through SMS.
· Establishes clear safety objectives and commitment to manage to those objectives.
· Defines methods, processes, and organizational structure needed to meet safety goals.
· Establishes transparency in management of safety.
what is the safety critical elements barrier?
Major accidents in the process industry typically involve failure of several protective layers, so the integrity of each Safety Critical Element (barrier) is vital to ensuringsafe operations. SCE's / barriers are physical or non-physical elements designed to prevent, control or mitigate of a major accident hazard.
What are SCE?
Safety Critical Elements (SCE) in the Chemical and Oil and Gas Industry are directed by a set of (regulatory) requirements for managing physical or non-physical elements. These elements (e.g. safety valves, lockout-Tagout procedures) represent safety barrier identified by their purpose to prevent, control, respond or mitigate the effect of a safety or environmental Major Accident (MA).
Why are SCE important?
The main purpose of identifying SCE and the related performance standards is to develop a focus on critical equipment and procedures. The idea behind SCE is that it is much more effective to manage a smaller number of unambiguous defined elements than to try to deal with everything that can be related to safety. Most companies are not able to manage their safety risk effectively without a structured approach and the reduction of complexity. The SCE methodology will constitute a considerable foundation to the management of these safety risks by the clear approach of the methodology and focus on the safety elements that really matter if taken into account the five most common pitfalls.
The five pitfalls
SCE are not defined by assessing the probability of failures and threats.
Often we do not have hard evidence to determine the probability of hazardous events, but we can determine the consequences of a failure or threat. Moreover In most risk based models the probability is considered null if a hazardous event have not taken place in the past. Of course is this no safety guarantee for the future and there is so a probability of risk. On the other hand, from a maintenance perspective it will not be in conflict with risk based concepts where the probability do have a significant role. SCE identification is required so the proper resources can be allocated and activities developed to reduce foreseeable risks. Risk based maintenance concepts could be one of those activities imposed to keep the SCE fit for purpose, if failure and degradation information become available.
SCE are not part of the elements designed to generate production or value.
There is an important difference between the elements which are designed for production or the reduction of value loss and those which reduces the risk of a major accidents. Where the first depends strongly on the economic and financial circumstances and targets, the SCE may not be compromised by cutting budgets or other monetary considerations.
Secondly, in most literature SCE are also elements through which failure could cause or contribute to a MA. This statement is questionable because even a toaster or almost all production related equipment have the potential to cause or contribute to an MA. In most cases fatal failure of production related equipment could cause a threat and the SCE is the barriers that prevents the scenario that leads to a Major Accident (MA). The consequence of using this broader definition and and misinterpretation of the relation between safety layers (SCE) and fatal failures of production related equipment (threats) is a higher probability that safety initiatives fail due to lack of focus and controlled complexity.
SCE are not only restricted to physical equipment.
There is considerable evidence that safety procedures and the applied human safety performance is more decisive to sustaining safety than equipment. While human induced failures are in many cases the initial case of major accidents, equipment is often the secondarily safety barrier to prevent or control a hazard. Moreover all failures induced by human activities, equipment and procedures along with external threats must be considered as a potential risk. Suitable procedures, human competencies and safety equipment must be in place and used to avoid that a major accident.
SCE identification process is more effective before commissioning.
The management of SCE is often monitored by regulatory bodies (e.g. UK, Norway, and Denmark) introduced after the asset was built and in operation. Assessing equipment, structures, systems and procedures and identifying SCE afterwards at this stage in the asset lifecycle is a labor-intensive process in which a whole team of specialists (e.g. operators, engineers, HSSE specialists etc.) is involved. In essence, this process is not as different as other mandatory safety studies before commissioning. If the SCE requirements are clear, it is far more logical and effective to integrate the SCE identification and the specification of its performance standards at the commissioning stage.
Handling SCE is not only applicable to production and maintenance departments.
Effective management of safety risks is strongly dependent on human capabilities. All staff must have the competence and the motivation to prevent hazardous failures, with the correct procedures to support. Departments who are involved in the recruitment of staff and the outsourcing of activities are at first responsible to develop and implement procedures to guarantee these human capabilities. Furthermore, although the introduction, monitoring and evaluation of SCE is a primary management responsibility, safety in general is the concern of everybody.
Finally where procedures and equipment does not replace human common sense it is also no excuse to violate safety procedures or disregard the upkeep of SCE.
Safety Instrumented Systems and Safety Critical Devices (T3000)
The proper application of Safety Instrumented Systems (SIS) is obviously important for process plants. However, non-SIS Safety Critical Systems (e.g., Safety Critical Devices) also play an important role. This session invites papers in the areas of: Safety Instrumented Systems - SIS design, SIL level determination, identification of IPLs, probability calculations, application of LOPA to SIS, etc. Safety Critical Devices (SCDs) - Examples, opportunities to apply SCDs instead of SIS, management of SCDs, application of LOPA to SCDs, etc.
What does a human factors engineer do?
Human Factors Engineers & Ergonomists. What they do: Design objects, facilities, and environments to optimize human well-being and overall system performance, applying theory, principles, and data regarding the relationship between humans and respective technology.
What is a human factors expert?
The Science of Human Factors. Human factors is a science that studies how people interact with or use all types of products, machines, equipment, and environments. Human factors experts study the effects of people's mental, perceptual, and physical capabilities and limitations on these interactions.
What does it mean by human factors?
In industry, human factors (also known as ergonomics) is the study of how humansbehave physically and psychologically in relation to particular environments, products, or services. ... A human factors specialist typically has an advanced academic degree in Psychology or has special training.
What is ergonomics in engineering?
Proper ergonomic design is necessary to prevent repetitive strain injuries and other musculoskeletal disorders, which can develop over time and can lead to long-term disability. Human factors and ergonomics is concerned with the "fit" between the user, equipment and their environments.
How much do human factors engineers make?
Human Factors Engineers and Ergonomists can earn a salary of Seventy Eight Thousand Four Hundred dollars on an annual basis. Human Factors Engineers and Ergonomists can make the highest salaries in Alaska, which has average pay of approximating $98790.
What is a human factors psychologist?
Human factors psychology is an interdisciplinary field which discovers and applies information about human behavior, abilities, limitations, and other characteristics to the design and evaluation of products, systems, jobs, tools, and environments for enhancing productive, safe, and comfortable human use.
What is a cognitive ergonomics?
Cognitive ergonomics is the discipline of making human-system interaction compatible with human cognitive abilities and limitations, particularly at work
What is a human factors engineer?
Human factors (HF) is the study of how people use technology. It involves the interaction of human abilities, expectations, and limitations, with work environments and system design. The term "human factors engineering" (HFE) refers to the application of human factors principles to the design of devices and systems
What is the human information processing system?
Human information processing is an approach to the study of human thought and behavior developed beginning in the 1950s as an alternative to the behavioral approaches that were popular at that time. It is a cognitive approach that is often equated with contemporary cognitive psychology.
what is surface safety valve?
Expro surface safety valves are hydraulically actuated failsafe gate valves designed to close upon loss of control line pressure. The valve is used to quickly shut in the well in the event of a leak to, overpressure or failure of any of the downstream welltest equipment.