Industrial safety systems
Encyclopedia
An industrial safety
system is a countermeasure crucial in any hazard
ous plants such as oil and gas
plants and nuclear plants. They are used to protect human
, plant
, and environment
in case the process
goes beyond the control margin
s. As the name suggests, these systems are not intended for controlling the process itself but rather protection. Process control
is performed by means of process control systems (PCS) and is interlocked by the safety systems so that immediate actions are taken should the process control systems fail.
Process control and safety systems are usually merged under one system, called Integrated Control and Safety System
(ICSS).
Industrial safety systems typically use dedicated systems that are SIL 2
certified at minimum; whereas control systems can start with SIL 1
. SIL applies to both hardware and software requirements such as cards, processors redundancy and voting functions.
These systems may also be redefined in terms of ESD/EDP levels as:
The FGS shall achieve these objectives by:
s, and these must be released in order to avoid any undesired consequences (such as pressure
increase in vessels and piping
). For this, emergency depressurization (EDP) systems are used in conjunction with the ESD systems to release (to a safe location and in a safe manner) such trapped fluids.
.
2. Prosafe RS by Yokogawa Electric Corporation
3. Safety Manager by Honeywell
4. HIMAX System by HIMA
5. Triconex by Invensys
Safety
Safety is the state of being "safe" , the condition of being protected against physical, social, spiritual, financial, political, emotional, occupational, psychological, educational or other types or consequences of failure, damage, error, accidents, harm or any other event which could be...
system is a countermeasure crucial in any hazard
Hazard
A hazard is a situation that poses a level of threat to life, health, property, or environment. Most hazards are dormant or potential, with only a theoretical risk of harm; however, once a hazard becomes "active", it can create an emergency situation. A hazard does not exist when it is not...
ous plants such as oil and gas
Petroleum industry
The petroleum industry includes the global processes of exploration, extraction, refining, transporting , and marketing petroleum products. The largest volume products of the industry are fuel oil and gasoline...
plants and nuclear plants. They are used to protect human
Human
Humans are the only living species in the Homo genus...
, plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
, and environment
Environment (biophysical)
The biophysical environment is the combined modeling of the physical environment and the biological life forms within the environment, and includes all variables, parameters as well as conditions and modes inside the Earth's biosphere. The biophysical environment can be divided into two categories:...
in case the process
Process Manufacturing
Process manufacturing is the branch of manufacturing that is associated with formulas and manufacturing recipes, and can be contrasted with discrete manufacturing, which is concerned with bills of material and routing....
goes beyond the control margin
Margin (economics)
In economics, a margin is a set of constraints conceptualised as a border. A marginal change is the change associated with a relaxation or tightening of constraints — either change of the constraints, or a change in response to this change of the constraints.- Extensive and intensive margins...
s. As the name suggests, these systems are not intended for controlling the process itself but rather protection. Process control
Process control
Process control is a statistics and engineering discipline that deals with architectures, mechanisms and algorithms for maintaining the output of a specific process within a desired range...
is performed by means of process control systems (PCS) and is interlocked by the safety systems so that immediate actions are taken should the process control systems fail.
Process control and safety systems are usually merged under one system, called Integrated Control and Safety System
Integrated Control and Safety System
Integrated Control and Safety System, or ICSS is a system that fuses the Process control and Safety control in an oil/gas facility.The practice in the oil/gas industry is to separate the Safety System from the Process Control System . Two independent systems for Process and Safety Systems allows...
(ICSS).
Industrial safety systems typically use dedicated systems that are SIL 2
Safety Integrity Level
Safety Integrity Level 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 ....
certified at minimum; whereas control systems can start with SIL 1
Safety Integrity Level
Safety Integrity Level 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 ....
. SIL applies to both hardware and software requirements such as cards, processors redundancy and voting functions.
Types of industrial safety systems
There are three main types of industrial safety systems in process industry:- Process Safety System or Process Shutdown System, (PSS).
- Safety Shutdown System (SSS): This includes Emergency Shutdown-(ESD) and Emergency Depressurization-(EDP) Systems.
- Fire and Gas System (FGS).
These systems may also be redefined in terms of ESD/EDP levels as:
- ESD level 1: In charge of general plant area shutdown, can activate ESD level 2 if necessary. This level can only be activated from main control roomControl roomA control room is a room serving as an operations centre where a facility or service can be monitored and controlled. Examples include:*in television production, the master control is the technical hub of a broadcast operation common among most over-the-air television stations, television networks...
in the process industrial plants. - ESD level 2: This level shuts down and isolates individual ESD zones and activates if necessary EDP.
- ESD level 3: provides "liquid inventory containment" and is
SSS
The safety shutdown system shall shutdown the facilities to a safe state in case of an emergency situation, thus protecting personnel, the environment and the asset. Safety Shutdown System shall manage all inputs and outputs relative to Emergency Shut Down (ESD) functions (environment & personnel protection). This system might also be fed by signals from the main fire and gas system.FGS
The main objectives of the fire and gas system are to protect personnel, environment, and plant (including equipment and structures).The FGS shall achieve these objectives by:
- Detecting at an early stage, the presence of flammable gas,
- Detecting at an early stage, the liquid spill (LPG and LNG),
- Detecting incipient fire and the presence of fire,
- Providing automatic and/or facilities for manual activation of the fire protectionFire protectionFire protection is the study and practice of mitigating the unwanted effects of fires. It involves the study of the behaviour, compartmentalisation, suppression and investigation of fire and its related emergencies, as well as the research and development, production, testing and application of...
system as required, - Initiating signals, both audible and visible as required, to warn of the detected hazards,
- Initiating automatic shutdown of equipment and ventilation if 2 out of 2 or 2 out of 3 detectors
- Initiating the exhausting system.
EDP
Due to closing ESD valves in a process, there may be some trapped flammable fluidFluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
s, and these must be released in order to avoid any undesired consequences (such as pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
increase in vessels and piping
Piping
Within industry, piping is a system of pipes used to convey fluids from one location to another. The engineering discipline of piping design studies the efficient transport of fluid....
). For this, emergency depressurization (EDP) systems are used in conjunction with the ESD systems to release (to a safe location and in a safe manner) such trapped fluids.
PSV
Pressure safety valves or PSVs are mechanical devices and are usually used as a final safety solution when all previous systems fail to prevent any further pressure accumulation and protect vessels from rupture due to overpressureOverpressure
The term Overpressure is applied to a pressure difference, relative to a "normal" or "ambient" pressure, in various circumstances:* In engineering: the pressure difference over the wall thickness of a pressure vessel...
.
Examples of Safety Systems and vendors
1. Trusted, AADVance by ICS Triplex, a Rockwell Automation company2. Prosafe RS by Yokogawa Electric Corporation
3. Safety Manager by Honeywell
4. HIMAX System by HIMA
5. Triconex by Invensys