What is Process Safety?
Process safety or functional safety or technical safety is a key element for any engineering design or any projects with planning as well as during execution of design at field locations. This is very important base for any industries to consider process safety or technical safety requirements and safe design goals for any project.
Health and safety, involves forming organized efforts and procedures for identifying workplace hazards and near miss accidents and exposure to unsafe environments and elements. However each and every industries should include training of workers/peoples/staffs in accident prevention, accident response, emergency preparation, and use of protective PPE’s (personal protective equipment’s), before joining any company and before starting any design or construction works.
Other than above personal safety, process or functional safety, environmental rules and regulations also very important to comply with creating a systematic approach for waste management or air/gases emissions.
Universally there are many different abbreviations used in various industries for health safety and environment or technical safety. However some of the common abbreviations used in Health, safety and environment are as below. It is all over combination to sometimes exclude environment or include safety and quality or health.
EHS or EH&S: Environment, health and safety
HSE: Health, safety and environment
HSEQ: Health, safety, environment and quality
HSSE: Health, safety, security and environment
HSSEQ: Health, safety, security, environment, and quality
OHS: Occupational health and safety
QHSE: Quality, health, safety, and environment
QHSSE: Quality, health, safety, security, and environment
SHE: Safety, health and environment
WHS: Work health and safety
Different Types of process and functional safety considerations:
Process safety
Process safety focuses on preventing fires, explosions and accidental chemical or hazardous gas releases in oil & Gas/refinery or chemical process facilities or any other industries dealing with hazardous materials production installations.
Process Safety Management is the prevention and mitigation of unplanned releases of highly hazardous process fluids like Hydrogen Sulphide (H2S), natural gas and volatile crude oil.
Occupational safety and health generally covers the management of personal safety. Now a days many industries are having well managed and developed systems in place, even they call for process safety reviews.
The tools, methods, programs etc. essential to achieve both process and occupational safety can sometimes be the same like work permit system and in other cases may have very different approaches. For Process safety Layers of Protection Analysis (LOPA) or Quantified Risk Assessment (QRA) are important, however for occupational safety, Personal Protective Equipment (PPE) is very much important.
This relates to chemical processes which releases unsafe chemicals, potentially hazardous materials, gases, steam which will be unplanned and hindrance of this emissions is process safety. Process safety emphases on prevention of spillage, leakages, equipment breakdown, over-pressures or temperatures, material corrosion aspects, metal fatigue and other releases/emission conditions.
This programs mainly focus on design and engineering of facilities, maintenance of equipment, effective safety alarms, effective safety controls, procedures and training to operation personal. Process safety is result of various discipline involvement together, which may consists of technical, management, operational persons to achieve success in process safety design.
Various Instrument devices are used to examine anticipated process or chemical reactions or undesired chemical reactions by process safety engineers or process chemists.
Reaction calorimeter is one of the instrument to check anticipated chemical reaction, this will consent a good measure of not only the reaction heat to be determined, but also to observe how much heat is “accumulated” during the various additions of chemicals.
This observation is done to see how much heat could be progressed if anything went wrong. Any proposed plant or industry need check, how much a plant can control heat output significantly less than the cooling capacity of plant, using various chemical reaction conditions by the chemist and has low accumulation.
Below are some of the devices used for monitoring undesired chemical reaction:
- Differential scanning calorimeter
- Reactive screening device
- Adiabatic calorimeter
Results received from above devices will be used for examining crude material, that are intended to be refined by distillation and allow the chemist to decide on maximum heat limit for the process that will not give rise to a thermal hit.
Functional Safety
Any plant or a system likely to have some operator errors, some of the hardware failures or any environmental changes occurs, which leads to unsafe environment in a plant and may cause damage to asset, overall system, plant, unit or equipment’s. To overcome these unsafe conditions Functional safety is very important. In short it is the part of the overall safety of a system or plant or unit or piece of equipment.
Main purpose of functional safety is to avoid undesirable risk of personal injury or damage to the health of people either directly or indirectly on account of damage to system, plant or to the environment.
Functional safety standards basically focus on electrical, electronic, and programmable systems, however functional safety methods have to extend to non-programmable parts of the system that, may actuate or operate, controls or monitors. This is called as end-to-end in scope in that it has to treat the function of a component or subsystem as part of the function of the whole system.
Level of performance of each and every specified safety function has to met, in order to achieve full functional safety. Following steps as a minimum, includes to achieve the process;
Identification:
Systematic identification of hazards, treats, unwanted events and their effects is the first step of functional safety. Furthermore, on account of these events, identifying what the required safety functions are available. There are various reviews and methods are used for identification of hazards and assessment of risks throughout the design, like for e.g. HAZID, HAZOP, QRA, etc.
Assessment:
Second step of functional safety is Assessment of above identified events or hazards for its potential severity of the consequences in terms of effects to people, assets, the environment and reputation including likelihood of these unwanted events.
This will involve a safety integrity level (SIL) or performance level or other quantification assessment. A SIL (or PL, AgPL, ASIL) applies to an end-to-end safety function of the safety-related system, not just to a component or part of the system.
Ensure:
Subsequent step is to make sure or ensure that safety functions perform to the design intent, even in case of incorrect operation of input or any failure modes. Ensuring these safety function, design and lifecycle managed by qualified and competent engineers carrying out processes to a recognized safety standard.
Verification:
Next step is verification using some appropriate tests, of safety systems assigned like SIL, ASIL, PL or agPL using mean time between failures and safe failure fraction (SFF). Probability of the system failing in a safe state is SFF: the critical states are identified from failure mode and critical analysis of the system.
Conduct:
Final step is to conduct functional safety audits. These audits are used to identify, examine and assess the evidence that the suitable safety lifecycle management techniques were applied consistently and thoroughly in the relevant lifecycle stages of product.
Management of Hazards in Process and functional safety
For brief details about Management of Hazards refer this link: Management of Hazards
HAZID (Hazard analysis)
For brief details about HAZID (Hazard identification or analysis) refer this link: HAZID (Hazard analysis)
HAZOP (Hazard and operability study)
SAFOP (Electrical Safety and Operability Study)
SIL (Safety Integrity Level Assessment)
Refer below some of the safety studies to be carried out in process industries:
FEA/FGDEA (Fire Explosion Assessment/ Fire Gas Dispersion Explosion Assessment)
Flare Radiation, Dispersion and Noise Analysis
RAM (Reliability, Availability and Maintainability) Study
HFE (Human Factors Engineering)
The impact of human factors on process safety shall be adequately considered. This will lead to improved operator performance and has the potential to lead to a reduction of lifecycle costs.
Human factors and ergonomics (commonly referred to as Human Factors), is the application of psychological and physiological principles to the (engineering and) design of products, processes, and systems. The goal of human factors is to reduce human error, increase productivity, and enhance safety and comfort with a specific focus on the interaction between the human and the thing of interest
Design Reviews
A design review is a milestone within a product development process whereby a design is evaluated against its requirements in order to verify the outcomes of previous activities and identify issues before committing to – and if need to be re-prioritise – further work. The ultimate design review, if successful, therefore triggers the product launch or product release.
The conduct of design reviews is compulsory as part of design controls, when developing products in certain regulated contexts such as medical devices.
By definition, a review must be conducted by persons who are external to the design team.
Most formalised systems engineering processes recognise that the cost of correcting a fault increases as it progresses through the development process. Additional effort spent in the early stages of development to discover and correct errors is therefore likely to be worthwhile. Design reviews are example of such an effort. Therefore, a number of design reviews may be carried out, for example 30%, 60% and 90% model reviews.
In Oil & Gas or refinery industries, the purpose of a 30 % model review in the Execute Phase is to freeze the basic plot layout and to reach agreement on the proposed design to enable the Contractor to proceed into detail design.
The purpose of the 60 % model review in the Execute Phase, is to confirm the design is in-line with the PEFS or P&ID, Supplier data and all other design relevant documentation. After the review the Contractor should be able to finalize the deliverable’s for construction.
The purpose of the 90 % model review in the Execute Phase is to confirm on the comments from the 60 % and to finalize on the total design of the model.
These reviews should be undertaken in detail, checking each unit for safety routes, operability, maintainability, accessibility and constructability and checking each piping system in the unit using the PEFS or P&ID to make item-by-item checks.
Quantitative Risk Analysis (QRA)
In quantitative risk assessment an annualized loss expectancy (ALE) may be used to justify the cost of implementing countermeasures to protect an asset. This may be calculated by multiplying the single loss expectancy (SLE), which is the loss of value based on a single security incident. With the annualized rate of occurrence (ARO), which is an estimate of how often a threat would be successful in exploiting a vulnerability.
The objective of the QRA is to increase understanding of the total process risk (on-plot & off-plot), transportation as well as occupational risks and predict LSIR, IRPA and PLL from the project and identify risk reduction measures for incorporation into design and operations.
The scope of QRA during Define and Execute phase is primarily to support the layout development and recommendation on the process safety measure i.e. reducing inventory, additional ESD valves etc. utilizing measures preferential hierarchy and to confirm to project management that tolerable risk levels have been achieved.
QRA study shall analyze the risk posed to plant property and personal life. It shall also include SIMOPS risks during construction of MMPS Gas Compression & Evacuation facilities.
Environmental Impact Assessment (EIA) study
To predict the significant chemical, biological and socio-economic effects of an activity and to make recommendations on activities, sites, techniques and technologies to be adopted in order to maximise the positive, and minimise the negative effects.
SIMOPS (Simultaneous operations)
SIMOPS are defined as activities that are performed by two or more work parties under different safety management arrangements may impact risks to one another. SIMOPS review shall identify key construction and operational activities that may affect one another.
MOPO (Matrix/Manual of Permitted Operations)
MOPO provides a guide to operations personnel when construction activities are planned to be undertaken during normal operations or when weather conditions deteriorate.
For the purpose of providing guidance in these matters, a Matrix/Manual of Permitted Operations (MOPO) shall be drawn up. It shall be a self-explanatory document, easy to interpret and use.
It serves to advise as a requirement to act accordingly and should only be disregarded following a well-documented risk assessment having been undertaken.
The matrix shall be drawn up with collaboration from all relevant disciplines on the project team. It needs to be developed during FEED/EXECUTE phase of the project, and then again verified after commissioning and before SIMOPS actually start. During this latter process, operations shall have significant input.
HAZARD Elimination, Minimization & Prevention
Following is the philosophy to be adopted as Hazard Elimination:
- Prevailing wind direction
- Sufficient separation and segregation of hazards in the layout design thereby reducing the possibility of escalation during an incident.
- Provision of suitable means for escape, muster and evacuation
- Effective separation of plant hazardous areas from safe areas in which personnel may normally work or gather in the event of an emergency, or where emergency equipment is located.
- The distance between fire areas shall be sufficient to avoid escalation of possible fires from one area to another. Also the distances between fire and explosion areas shall be sufficient to minimize the impacts.
- Equipment layout will consider strategies to maximize the natural ventilation and optimize orientation and spacing of equipment and piping for mitigation of explosion overpressures.
- As far as is practicable piping, flanges, valves and other equipment with the potential for pressurized gas release should be positioned to avoid jet fire impinging on critical items, such as escape routes or other pressure systems.
- Following is the philosophy to be adopted as Hazard minimization..
- ESD valves to be located outside the impact zone any fire scenario or at the distance mentioned in standards.
- Adequate Fire & Gas detectors to be provided at strategic location. Providing the detectors will initiate partial or full shutdown leading to minimize the hazards.
Following is the philosophy to be adopted as Hazard Prevention
- Provision of Active & Passive fire protection shall be used for Hazard Prevention
- Emergency Evacuation, Escape routes etc.
Fire and Gas Detection Philosophy
The objective of Fire and Gas (F&G) detection is to facilitate an early warning to personnel of potentially dangerous situations in terms of flammable gas, toxic gas or fire and to enable manual or automatic initiation of remedial actions to avoid/minimize escalation of events, e.g. shutdown. All detectors shall be integrated into a fire and gas logic system which shall form part of the independent safeguarding system.
The fire and gas detection systems (FGS) shall be developed and implemented for the facilities for the protection of personnel, the environment and assets by:
- Continuous monitoring of designated areas for release or accumulation of flammable or toxic gases;
- Initiation of alarms to alert personnel to the hazard; and
- Initiation of executive actions to mitigate such events and to prevent escalation.
F&G Philosophy shall address field mounted detectors like flammable gas, toxic gas, manual call points, fire detectors, heat detectors, beacons and the sounders etc.
Emergency Shutdown Philosophy
ESD valves are designed to;
- Isolate the process facility from the hydrocarbon inventories in the pipelines entering and leaving the site (i.e. incoming well fluids, export liquids, export gas);
- Segregate significant inventories within the central processing facility to limit the quantity of material released on loss of containment;
- Control potential ignition sources by shutdown of non-intrinsically safe equipment;
- Initiate blowdown; and
- Initiate actions in utility systems to mitigate hazardous events e.g. shutdown of control building HVAC.
The system shall be designed so that it is capable of fulfilling its function under the conditions which may be experienced when the system is required to operate.
ESD valves plus their actuating system shall remain operational for at least 15 minutes, or for as long as necessary to fulfil their intended function. Where practical, this shall be achieved by locating the valves outside the area where they could be impaired by fire or explosion.
Manual actuation buttons shall be located at a safe distance from the fire risk area, preferably on entry and exit routes.
Hazardous Area Classification
For brief details about Hazardous area classification refer this link: Hazardous Area Classification
Escape & Evacuation
For brief details about escape and evacuation refer this link: Escape and Evacuation
Safety Signs in Process and functional safety
The provision of safety signs is an important feature of personnel safety. There are six basic categories of signs as follows:
- Fire Fighting: Those giving information/instructions with regard to fire prevention and firefighting equipment
- Mandatory: Those giving instructions or information which must be obeyed or observed
- Emergency: Those giving instructions to be followed in cases of emergency
- Warning: Those giving information which should be heeded to avoid possible dangerous occurrences
- Prohibition: Those which prohibit a particular activity;
Signs used for firefighting and emergency purposes shall be visible in low light conditions and will therefore be manufactured from photo luminescent materials.
All text shall, as a minimum, be in English and Local languages.
Personal Protective Equipments in Process and functional safety
Personal Protective Equipment (PPE) comprises a range of clothing and equipment which is worn by the individual to protect or shield their bodies from workplace hazards.
Employers shall, provide their employees with sufficient, fit for purpose personal protective clothing and equipment to protect them against workplace hazards, without any cost to the employees.
In the Hierarchy of Controls (Elimination, Substitution, Isolation, Engineering, Administration and PPE), personal protective equipment is considered the least satisfactory method in the prevention of work-related injury or illness and is only to be used when other measures are not feasible or cannot be implemented immediately. Provision of PPE shall always be accompanied with information, instruction and training as to the correct use and limitations. PPE shall be selected following a documented risk assessment and shall meet.
Environment Protection
Environmental requirements include:
- The management of project activities shall recognize the consequences of the development, whereby environmental aspects are considered including social and health issues.
- Minimizing emissions of greenhouse gases where possible (in line with MECA guidance – new installations shall be designed not to flare or vent hydrocarbons continuously for disposal).
- Hazardous and non-hazardous wastes shall be identified, segregated, appropriately stored and managed.