RISK BASED INSPECTION
(API 580, API 581)

We Prepare in the Best Way.
"Audit and Secure Your Processes!"

What is Corrosion?

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Corrosion; These are the losses that occur in the material as a result of chemical and electrochemical reactions between the material and its environment. All building materials can be corroded directly or indirectly. However, corrosion is a type of structural damage that affects metals in particular and progresses slowly.

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Risk Based Audit - What is RBI?

RBI is used to identify and understand risk, risk factors, and where the equipment is in its lifecycle.

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Many refining and petrochemical plants must cope with mountains of process safety and engineering information. This critical information is usually distributed in the file room, drawer or existing application sections. Perhaps a bigger problem is that maintenance, engineering, safety, operations and other departments maintain different versions of the same information. Moreover, this information often has to be recreated or verified over and over again by different needs and different disciplines.

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In the Risk Based Inspection process, engineers design inspection strategies to prevent predicted or observed degradation mechanisms (what, when, how to inspect).

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Risk Based Audit (RBI) plans are a planning tool used to create the optimum plan for conducting audit activities. RTK uses the findings of a formal risk analysis, such as a Corrosion Risk Assessment, to guide inspection planning and determination of physical inspection procedures.

A risk-based approach to audit planning is used to:

• Evaluation of process operations that will affect production, operation and material integrity,

• Ensuring that the risk is reduced to the lowest acceptable level,

• Determining the remaining lives of assets,

• Identifying operational risks using accepted industry standards,

• Determining appropriate surveillance intervals,

• Review of technical specifications and construction materials,

• Defining the risk ranking level in detail and determining the relevant risk acceptance level,

• Developing a corrosion management plan,

• Carrying out corrosion cycle mapping,

• Using the most appropriate methods for detection and examination,

• Making efforts for focused inspection on the most critical areas,

• Optimizing audit programs,

• Detailed description of required supervision and maintenance tasks.

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Risk-based auditing practice allows developing the best approach for surveillance activities by using risk analyses. It also allows you to achieve the following while managing maintenance processes;

• Analyzing the possibilities and consequences of failure,

• Compliance with all relevant applicable regulations and the requirements of the Regulation on the Prevention and Mitigation of Major Industrial Accidents,

• Developing a risk-based surveillance and maintenance program,

• Ensuring mechanical integrity and reliability,

• Ensuring that inspection and maintenance resources are focused on plant elements and parts that pose the highest risk.

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Risk Assessment:

There are many methods that can be applied by workplace officials to determine error scenarios. These methods are distinguished from each other by the details taken into account in describing and measuring the events that create the error or after the error occurs in a structure. Basic specialist techniques listed below can be used;

• Hazard and Operability Analysis (HAZOP)

• Possible Error and Effects Analysis (FMEA)

• Fault Tree Analysis (FTA)

• Event Tree Analysis (ETA), etc….​

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RBI Standards:

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API Publication 581 – Risk Based inspection, Base Resource Document – 1st edition 2000.

API Publication 580 – Recommended Practice for Risk Based inspection – 1st edition 2002.

Publication No. API 581 is a fundamental document for Risk Based Inspection (RBI) and is an industry-specific resource used in petrochemical and chemical process fields. The Risk Based Inspection (RBI) program should aim to:

Defining the level of risk associated with an item and measuring its magnitude,

Evaluating occupational safety, environmental and work interruption or interruption risks,

Reducing the risk of errors occurring by using effective control resources.

According to API 581, failure probability is the probability that a given error event will occur with the average frequency or severity over a specified time interval, usually taken as one year. The qualitative approach is done by applying a 5 x 5 risk matrix to each element. The probability of the error occurring is found by the sum of the following 6 (six) weighted factors.

• The number of equipment in an installation,

• Damage mechanism,

• The degree of impact of the audit,

• The current condition of the equipment,

• nature of the process,

• Safety design and mechanism.

The consequences of the error are divided into only two factors:

• Fire/Explosion

• Toxicity

General approach of quantitative analysis; It is based primarily on determining the details of the process and compiling equipment and other relevant information. The risk is then calculated by multiplying each error outcome by each damage scenario. Total risk is equal to the arithmetic sum of all scenario risks.

Risk = CS x FS

S = Scenario

CS = Results of the scenario

FS = Scenario occurrence frequency

According to API 581, error risk requires evaluating the probability of an error occurring together with measuring the consequences of that error. If it is possible to determine these two parameters numerically, then the risk; It is equal to the product of the probability of an error occurring and the damage resulting from the error.

RiskITEM = Σ RiskS

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Why Is It Important to Understand Corrosion Damage Mechanisms?
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A corrosion damage mechanism is a mechanical or chemical process that causes equipment damage or material degradation.

API RP 584 says it best:

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"In today's operating environment, it is not enough to base future inspection plans solely on previously recorded/known equipment condition history. A basic understanding of the process/operating conditions and resulting damage mechanisms is essential to establishing and maintaining an inspection program that has the highest probability of detecting potential damage." It is necessary for

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Proper identification and understanding of the damage location (general or local), damage propagation rates, and damage mechanisms are required to determine mitigation opportunities.

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Relevant Standards and Guides:

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• API Recommended Practice 571 and ASME, NACE Corrosion Damage Mechanism Atlas have been published to provide guidelines for equipment inspection personnel and engineers to assist in identifying possible causes of damage.

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• API 571-2020 standard includes a total of 67 damage mechanisms, refining and petrochemicals, liquid fuel, chemical storage and use, paper pulp, etc. It includes damage mechanisms commonly seen in various industries, including:

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• Also ASME, NACE corrosion Atlas, AIChE, BSI, McGraw-Hill etc. Corrosion Engineering Handbooks are available.

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• For example; The ASME, NACE Corrosion Damage Mechanism Atlas (National Association of Corrosion Engineers) identifies 850 service-induced corrosion damage and degradation mechanisms, including corrosion and other types of metallurgical damage, that are most likely to affect the condition of materials.

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How Is The Corrosion Mechanism Extraction and Mapping Service Performed?

Corrosion mechanisms extraction and mapping service is a process that includes a set of activities required to detect, manage and prevent damage caused by corrosion in industrial facilities. This service is typically carried out by materials engineers, corrosion experts and plant operators. The basic content of the service is given below:

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• Facility Inspection: The first step involves a general inspection of the industrial facility. This is the process of understanding the type of facility, its size, materials used and operating conditions. This information is used to identify areas potentially affected by corrosion.

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• Determination of Corrosion Mechanisms: Corrosion mechanisms can be caused by different chemical, physical or environmental factors. Identifying these mechanisms is important to understand which type of corrosion is involved. This helps understand how corrosion occurs.

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• Evaluation of Corrosion Damage: The extent and severity of corrosion damage to the equipment and structures within the facility are evaluated. The extent of damage helps determine the need for repair or replacement.

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• Measurements and Data Collection: Measurements are taken to determine the extent, depth, and distribution of corrosion damage. This may include a detailed inspection of sensitive equipment and structure.

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• Mapping and Reporting: Locations of corrosion damage within the facility are mapped and reported. These maps show which areas require immediate attention and which areas require regular maintenance. Reports include the causes of corrosion and suggested solutions.

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• Developing Corrosion Control Strategies: Strategies are developed to control corrosion. These strategies include measures to prevent, monitor and manage corrosion. This may include material selection, coating applications and regular maintenance.

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• Documentation and Monitoring: Data obtained throughout the process of extracting and mapping corrosion mechanisms is regularly updated and monitored. This helps monitor the long-term performance of the facility.

This service is critical to improving the safety and efficiency of the facility. Early detection and effective management of corrosion mechanisms is necessary for the sustainability of industrial facilities.