Within the Context of Seveso II, Importance of Risk-Based Inspection in Oil, Gas and Petrochemical Industry (XIX World Congress on Safety and Health)
?zlem ?ZD?LEK ?SLAMO?LU
?al??ma ve Sosyal Güvenlik Bakanl??? - Emekli Ba? ?? Müfetti?i
?zlem ?ZKILI?
?zlem Academy A?. - General Manager
Msc., Chemical Engineering -ASQ -Reliasoft Reliability Expert
A Class Occupational Safety Expert
Senior Non-Key Expert - EuropeAid Turkey Project -Technical Assistance on Increasing the Implementation Capacity of the Seveso II Directive Tranning (EuropeAid130724/D/SER/TR)
Labour Inspector - Ministy of Labour and Social Security
More than 20 years of national and international experience as an institutional and a consultant in the field of health and safety
The Regulation on the Control of Major Industrial Accidents: Seveso Directive
After the serious industrial accident happened in Seveso, Italy in 1976, a Directive (82/501/EEC) has been agreed regarding the accident prevention in industrial installations. Afterwards, two accidents which happened in Bhopal, India in 1984 and Basel, Switzerland in 1986 have resulted in the amendment of this directive.
Seveso-III (Directive 2012/18/EU)
In Europe, the catastrophic accident in the Italian town of Seveso in1976 prompted the adoption of legislation on the prevention and control of such accidents. The so-called Seveso-Directive (Directive 82/501/EEC) was later amended in view of the lessons learned from later accidents such as Bhopal, Toulouse or Enschede resulting into Seveso-II (Directive 96/82/EC). In 2012 Seveso-III (Directive 2012/18/EU) was adopted taking into account, amongst others, the changes in the Union legislation on the classification of chemicals and increased rights for citizens to access information and justice. It replaces the previous Seveso II directive.
The Seveso Directive has brought about various control obligations concerning the prevention of major industrial accidents involving hazardous substances. The plants within scope of the Seveso Directive are obliged to prepare safety reports and emergency action plans.
The Directive now applies to more than 10 000 industrial establishments in the European Union where dangerous substances are used or stored in large quantities, mainly in the chemical, petrochemical, logistics and metal refining sectors.
Considering the very high rate of industrialisation in the European Union the Seveso Directive has contributed to achieving a low frequency of major accidents. The Directive is widely considered as a benchmark for industrial accident policy and has been a role model for legislation in many countries world-wide.
As a result of the review process, on 4 July 2012 the new Directive 2012/18/EU (aka Seveso-III) was adopted which repeals the Seveso II Directive 96/82/EC by 1 June 2015.
The principles
The Seveso Directive aims at the prevention of major accidents involving dangerous substances. However, as accidents may nevertheless occur, it also aims at limiting the consequences of such accidents not only for human health but also for the environment.
The Directive covers establishments where dangerous substances may be present (e.g. during processing or storage) in quantities above a certain threshold. Excluded from the Directive are certain industrial activities which are subject to other legislation providing a similar level of protection (e.g. nuclear establishments or the transport of dangerous substances).
Depending on the amount of dangerous substances present, establishments are categorised in lower and upper tier establishments, the latter are subject to more stringent requirements.
Current situation in Turkey: By-law on Reducing Major Industrial Accident Risks (BEKRA Legislation):
Known as Seveso II Directive, Regulation on Prevention of Major Industrial Accidents and Mitigation of Their Effects concerning especially chemical factories was published in the Official Gazette No. 28867 of 30.12.2013 and the effective date of this Regulation has been postponed till 01/01/2017 in Turkey
Seveso Directive requires the preparation of a Major Accident Prevention Policy. This policy should demonstrate that all the necessary measures have been taken to prevent major accidents and limit their consequences to persons and the environment. It recognizes that risk cannot always be completely eliminated, but there is a inversely proportional relationship between the risk and the measures taken to control the risk.
The Annex-1 of the By-Law contains two lists, namely Named Substances and Categories of Unnamed Substances. Both lists contain lower threshold of quantities and upper threshold of quantities. These lists indicate two categories for dangerous substances named Upper- Tier and Lower-Tier.
After operators notify their dangerous substance to BEKRA Notification System, system establishes assigns of the establishment automatically.
Scope of the establishment is classified as;
- Upper-Tier Establishment
- Lower-Tier Establishment
- Out of Scope
As a result of this notification, the establishments classified as upper tier and lower tier ones should perform the liabilities listed in the following table:
Common liabilities for all upper tier and lower tier establishments:
- Notification
- Quantitatif Risk assessment
- Major Accident Prevention Policy - MAPP
- Domino Effect: Information exchange
- Liabilities in case of major accident: Action, Communication and Reporting
- Liabilities for upper tier establishments:
- Safety report
- Risk-Based Inspection (RBI) and Reliability centered maintenance (RCM)
- Safety Management System
- External Emergency Plan: Preparation, Review and Updating
- Information Sharing for Preparation of External Emergency Plan
- Public information
What is Risk-Based Inspection Why It is Necessary?
The Control of Major Accident Hazards Regulations (COMAH or Seveso II) cover the control of major accident hazards at installations as a whole. Such installations may include atmospheric storage tanks, process pipework and other equipment containing flammable or toxic and other hazardous materials.
Preventing the loss of containment system of hazardous substances is often key to avoid major accidents. It is therefore necessary to take appropriate measures to achieve adequately continuous integrity of containment equipment (vessels, tanks, pipework etc.). A suitable scheme of in-service examination can therefore be an important part of the necessary measures to avoid major accidents, but is not an explicit requirement of the Seveso regulations.
The Oil, Gas and Petrochemical Industry is facing tough challenges regarding risk mitigation to improve safety and reliability on the one hand cost pressure about the risk mitigation measures on the other hand. However, in most cases the highest risk is mostly associated with a small percentage of plant items. These potential high-risk components require a greater degree of attention than others. Knowing which areas to prioritize becomes paramount. Therefore it is essential to balance inspection costs and risk through the use of an appropriate technology for inspection and maintenance planning. One of the best methodologies for providing an effective inspection and maintenance program is Risk Based Inspection (RBI).
Effective implementation of a Risk Based Inspection program extends the operating life of equipment and piping, safely and cost effectively. RBI is accepted as good engineering practice for the implementation of inspection and maintenance programs and has its roots in Process Safety Management and Mechanical Integrity programs. The objective, principals and practices of Risk Based Inspection are demonstrated and explained.
Risk-based inspection refers to the application of risk analysis principles to manage inspection programs for plant equipment. RBI has been used in the nuclear power generation industry for some time and is also employed in refineries and petrochemical plant. The ultimate goal of RBI is to develop a cost-effective inspection and maintenance program that provides assurance of acceptable mechanical integrity and reliability.
Causes of Failure:
Any unintentional release of stored energy and/or hazardous contents from a pressure system or containment constitutes a failure. Failure usually involves a breach in the containment boundary and a release of contents into the environment. In extreme cases, stored energy may be released as a high pressure jet, missiles, structural collapse or pipe whip and contents may be flammable and/or toxic.
Root causes of failure of pressure systems, tanks and other containers include:
- Inadequate design and/or material for the loading and operating environment.
- Incorrect and/or defective manufacture.
- Unanticipated in-service deterioration such as corrosion or fatigue cracking.
- System errors in operation or maintenance or over-pressure protection.
- Malfunction of instrumentation, control systems or feed and utility supplies.
- Human factors including deliberate damage.
- External events such as fire, impacts or storms.
Risk Assessment:
There are many techniques available for Duty Holders to use to identify accident scenarios. They differ in the degree of detail to which events leading up to and after the failure are identified and quantified within a logical structure. The following lists the main specialist techniques that may be used:
- Hazards and Operability Study (HAZOP)
- Failure Modes and Effects Analysis (FMEA)
- Fault Tree Analysis (FTA)
- Event Tree Analysis (ETA)
- Human Reliability Analysis (HRA)
What is Risk based inspection (RBI):
Risk based inspection (RBI) is a method in which assets are identified for inspection based on their associated risks as opposed to a predetermined fixed time interval. In other words, it is a prioritizing and planning tool, predominantly used in the oil and gas industries, which aids in the identification of high priority items (i.e., those with high risk) vs. low priority items (i.e., those with low risk). This approach allows the users/owners of the assets to maximize the effectiveness of their inspection resources by concentrating them on those assets that pose the highest risk and not wasting resources on assets that are, in essence, inconsequential.
API Publication 581, a base resource document for Risk Based Inspection is an industry specific document designed to be applied to the petroleum and chemical process areas. According to the API 581, it recognizes that a RBI program aims to:
- Define and measure the level of risk associated with an item.
- Evaluate safety, environmental and business interruption risks.
- Reduce risk of failure by the effective use of inspection resources.
According to the API 581, the probability of failure is the mean frequency or rate with which the specified failure event would be expected to occur in a given period of time, normally one year.
The qualitative approach assesses each plant item with a position in a 5 x 5 risk matrix. The likelihood of failure is determined from the sum of six weighted factors:
- Amount of equipment within item.
- Damage mechanism.
- Usefulness of inspection.
- Current equipment condition.
- Nature of process.
- Safety design and mechanisms.
The consequence of failure is divided into only two factors:
- Fire/Explosion.
- Toxicity.
The general approach of the quantitative analysis is to first establish details on the process, the equipment and other pertinent information. Risk is then calculated as the product of each consequence and likelihood for each damage scenario, the total risk for an item being the sum of all the scenario risks:
According to the API 581, the risk of failure combines the probability of failure with a measure of the consequences of that failure. If these are evaluated numerically, then the risk is defined as the product of the probability of failure rate and the measured consequence.
Basic Concepts:
In risk based inspection, risk is calculated as the product of the probability of failure and the consequence associated with a failure:
Risk = Probability of Failure x Consequence of Failure
Risk is usually considered a better measure for prioritization than either the probability of failure alone or the consequence of failure alone, because it is more descriptive of the actual damage/loss caused. As an example, if you need to prioritize two assets where one asset has a high probability of failure but low consequence of failure, and the other asset has a low probability of failure but a high consequence of failure, the analysis would yield completely opposite results if you considered only one factor or the other. The use ofrisk eliminates this ambiguity.
The probability of failure (POF) is determined using applicable damage factors (mechanisms), a generic failure frequency and a management system factor:
POF(t) = 1 – e-gff x FMS x Df(t)
where:
- gff is the generic failure frequency.
- FMS is the management system factor.
- Df(t) is the overall damage factor.
The generic failure frequency is based on industry averages of equipment failure. The management system factor is a measure of how well the management and labor force of the plant is trained to handle both the day-to-day activities of the plant and any emergencies that may arise due to an accident. The overall damage factor is the combination of the various damage factors that are applicable to the particular piece of equipment being analyzed.
The consequence of failure is calculated as the combined values of the consequences for damage to the failed equipment, damage to the surrounding equipment, loss of production, the cost due to personnel injury and the damage to the environment. The consequence of failure can include both a financial consequence (FC) and an area (safety) consequence (CA).
FC = FCcmd + FCaffa + FCprod + FCinj + FCenviron
CA = max (CAequip, CApersonnel)
- FCcmd is the financial consequence to failed equipment.
- FCaffa is the financial consequence to surrounding equipment.
- FCprod is the financial consequence due to production downtime.
- FCinj is the financial consequence due to personnel injury.
- FCenviron is the financial consequence due to environmental damage/cleanup.
- CAequip is the area consequence to surrounding equipment.
- CApersonnel is the area consequence to nearby personnel.
For further detail on calculating probability of failure and/or consequence of failure, please consult API RP 581.
Process of Risk Based Inspection:
Many refining and petrochemical plants struggle with a mountain of process safety and engineering information. This critical information is often scattered in file rooms, drawers or legacy applications. Compounding the problem are multiple versions of the same information housed in maintenance, engineering, safety, operations and other functional areas. What’s more, the information is often recreated and revalidated over and over again by different disciplines with different needs.
During the RBI process, engineers design inspection strategies (what, when, how to inspect) that most efficiently match forecasted or observed degradation mechanisms.
Risk Based Inspection (RBI) schemes are a planning tool used to develop the optimum plan for the execution of inspection activities. RBI uses the findings from a formal risk analysis, such as a Corrosion Risk Assessment, to guide the direction and emphasis of the inspection planning and the physical inspection procedures. A risk based approach to inspection planning is used to:
- Ensure risk is reduced to as low as reasonably practicable
- Optimize the inspection schedule
- Focus inspection effort onto the most critical areas
- Identify and use the most appropriate methods of inspection
RBI provides a logical, documented, repeatable methodology for determining the optimum combination of inspection frequencies and inspection scopes. RBI objective is to ensure focus of inspection to areas with high risk, while inspection in areas with low risk will be reduced or excluded from the normal inspection program and therefore result in significant inspection and maintenance cost reduction.
CONCLUSION:
The concept of risk analysis has been around for a long time and Risk Based Inspection (RBI) programs have generated considerable interest in industry. Risk-Based Inspection is a process that identifies, assesses and maps industrial risks (due to corrosion and stress cracking), which can compromise equipment integrity in both pressurized equipment and structural elements. RBI addresses risks that can be controlled through proper inspections and analysis.
The consequence of failure through the unintentional release of stored energy and hazardous material is the potential for harm. Duty Holders have a responsibility to assess the potential harm to the Health and Safety of employees and/or the public, and to the environment from pollution and other damage. They may also legitimately consider the consequences of failure on their business, such as the costs of lost production, repair and replacement of equipment and the damage to of the company reputation.
The inspection program is being developed to reduce that risk. To do this we need to know the following issues;
- What type of damage to look for?
- Where to look for damage.
- How to look for damage.
- When to look for damage.
An integrated integrity management strategy will contain measures that address and mitigate the possibility of root causes of failure. Design reviews, manufacturing quality assurance, operating training, and systems analyses are examples of such measures. In-service inspection is a backstop to prevent failure when a root cause has led to deterioration from the design intent or the as manufactured condition.
Although RBI is quite a new concept and not known very well in our country, for the reasons outlined previously, it should be paid attention and its widely acceptance should be promoted.
REFERENCES:
- API Publication 581 – Risk Based inspection, Base Resource Document – 1st edition 2000.
- API Publication 580 – Recommended Practice for Risk Based inspection– 1st edition 2002.
- HSE, Best Practice for Risk Based Inspection as a part of Plant Integrity Management, Contract Research Report 363/2001
- Ramesh J. P., Risk Based Inspection, Middle East Nondestructive Testing Conference & Exhibition - 27-30 Nov 2005 Bahrain, Manama