Layers of Protection Analysis and Safety Integrity Level (LOPA & SIL)

Introduction

This highly participative Layers of Protection Analysis training course combines both qualitative and quantitative elements of hazard evaluation and risk assessment to analyze and judge the adequacy of existing or proposed safeguards against process deviations and accident scenarios. It uses an order of magnitude approach to quantify the likelihood of causes, the likelihood of failure of Independent Protection Layers (IPLs), and estimate the consequences for chosen accident scenarios. These approximations are used to estimate the risk of a scenario.

A key to the success of Layers of Protection Analysis (LOPA) is its rules for judging if protection layers are truly independent. Because of these rules, LOPA helps the analysts make consistent judgments of if the risk of a scenario is “as low as reasonably practical (ALARP)”. The training course contents are based and taught on the guidelines from the AIChE / HSE. The training course covers all aspects of how to apply this very useful technique not only in the selection and analysis of Safety Integrated Systems but also for other applications within an organization such as Capital Improvement Planning, Management of Change, Risk-Based maintenance programs, Incident Investigations, etc.

This course is designed to deliver expert instruction on how to successfully plan and execute Safety Integrity Level (SIL) Determination studies efficiently, effectively, and in accordance with the IEC 61511 standard. This includes understanding the principles behind three of the most commonly used SIL Determination methods (Layer of Protection Analysis, Calibrated Risk Graph, and Safety Layer Matrix), learning how to deal with challenging personalities within the SIL team and how to avoid common pitfalls and traps so your studies run smoothly.

LOPA is a semi-quantitative risk analysis technique. It lies between a HAZOP and a quantitative risk assessment (QRA) in terms of its rigorousness. This technique evaluates risks by orders of magnitude of the selected accident scenarios and builds on the information developed in qualitative hazard evaluation (e.g. PHA).

The layer of protection analysis (LOPA) is a semi-quantitative tool for analyzing and assessing risk on a process plant. It uses an order of magnitude technique to evaluate the adequacy of existing or proposed layers of protection against known hazards. LOPA typically builds on the information developed during a qualitative hazard evaluation, such as a process hazard analysis (PHA) or Hazard and Operability Study (HAZOP), and can be used to meet the risk assessment requirements of IEC 61508 and 61511 standards. This course describes each step in performing LOPA and uses examples, exercises, and workshops to provide experience in its application.

Objectives

Learn how to perform a LOPA study to evaluate the effectiveness of process safeguards. Understand how to use LOPA, Risk Graph, and Risk Matrix methods to select SILs for SIFs. LOPA is often used as an extension of process hazard analysis (PHA). PHA teams use engineering judgment to decide if additional safeguards are needed to protect against accident scenarios they identify. This subjective approach can lead to disagreements and possibly inappropriate measures to reduce risk. A more rational and objective approach is needed, at least when considering risk remediation measures for high-risk scenarios or those that are expensive to implement. LOPA was developed for this purpose.

• When and how to use LOPA
• How to identify which scenarios from a HAZOP or other qualitative analysis could benefit from LOPA
• How to systematically create risk scenarios for new processes or for existing processes under change
• How to establish risk acceptance (risk tolerance) criteria for use within your company (this is also called the development of ALARP criteria) and how to depict this in a Risk Matrix or in a formula
• SIL / PHA / HAZOP team leaders & scribes
• Engineers involved in any aspect of the SIS Safety Lifecycle
• Supervisors, managers, and engineers responsible for SIL studies
• How to calculate “as-is” risk for a cause-consequence pair:
• How to estimate the frequency of the initiating event
• How to determine the consequence for the scenario (unmitigated)
• Understand what is meant by “independence” and “uniqueness” with respect to the safeguard layers (IPLs)
• How to calculate the value of each IPL
• How to determine the risk of a LOPA scenario and how to determine how much further risk reduction (if any) is necessary
• How to use LOPA to determine the Safety Integrity Level (SIL) necessary for an instrument IPL (to comply with the requirements of IEC 61508/61511 for safety instrumented systems)
• How to document LOPA
• How other companies worldwide use LOPA to:
• Decide which PHA / HAZOP recommendations to reject and which to accept
• Focus limited resources within mechanical integrity departments and  operations on what is critical to managing risk to ALARP
• Avoid wasting resources on the added cost and unproductive sophistication that often occurs when they instead quantify risk using QRA methods such as fault tree and event tree analysis

Training Methodology

This is an interactive course. There will be open question and answer sessions, regular group exercises and activities, videos, case studies, and presentations on best practice. Participants will have the opportunity to share with the facilitator and other participants on what works well and not so well for them, as well as work on issues from their own organizations. The online course is conducted online using MS-Teams/ClickMeeting.

Who Should Attend?

• Process safety personnel, PHA analysts, control systems engineers, project engineers, and other personnel who need to apply or understand LOPA, Risk Graphs, or Risk Matrices.
• Professionals and leaders who wish to learn more about strategies for improving Process Safety Management and the use of the various Layers of Protection to improve the Safety Integrated Systems and Process Safety of their operations
• Professionals and leaders within an organization responsible for Capital Improvement Planning, Management of Change, Risk-Based maintenance programs, Incident Investigations, Emergency planning and response, Facility siting and or design
• Personnel moving into roles that are participating or are responsible for the Safety Integrated Systems and Process Safety of their operations or Capital Improvement Planning, Management of Change, Risk-Based maintenance programs, Incident Investigations, Emergency planning and response, Facility siting and or design.

Course Outline

Day 1: Introduction to Layers of Protection Analysis (LOPA)

• Learning objectives and goals of using the LOPA technique
• What is LOPA? How is LOPA applied?
• Terminology and definitions
• Where does LOPA fit into Process Safety and the other Process hazard Assessment methods?
• How to Implement LOPA
• Introduction to Reliability Technology
• Reliability of components, series and parallel systems
• Types of maintenance and inspection regimes

SIL Practices

• SIL Determination Workshop
• Calibrated Risk Graph
• The layer of Protection Analysis (LOPA)
• Safety Layer Matrix
• Background to SIL Determination
• SIL Determination Methods
• SIL Determination Method Selection Criteria
• SIL Documentation Issues
• SIL Teams

Day 2: Identification of Initiating Events

• Hazard & Operability ‘HAZOP’ Study
• HAZOP Workshop
• Risk Assessment & Risk Management
• Analysis of Major Accidents in relation to LOPA:
  • Piper Alpha
  • BP Texas Refinery Explosion
  • Bhopal
  • Buncefield
• How to decide if a process needs a Safety Instrumented
• System (SIS) and what SIL levels it needs.

Day 3: Estimating the Consequences and Severity

• Estimating the Consequences and Severity
• Mechanics of Fire, Explosion, and Toxic Releases
• Consequence evaluation approaches for LOPA
• Developing Scenarios
• Selecting candidate scenarios from qualitative (brainstorming) hazard evaluations
• Scenarios from design questions and from incidents
• Deciding on the right cause-consequence pair to define each scenario
• Identifying Independent Protection Layers
• Purpose
• Definition and Purpose of an IPL
• IPL Rules
• LOPA IPL Assessment
• Examples of IPL’s
• Preventive IPL vs Mitigating IPL
• Continuing Examples
• Protective Systems Design and Reliability
• The concept of Fractional Dead Time ‘FDT’
• High Integrity Protective Systems
• Selection of Safety Integrity Levels ‘SIL’
• Using LOPA to make risk decisions
• Comparing Calculated risk to Scenario Risk Tolerance
• Expert Judgement
• Using Cost / Benefit Comparisons
• Comparison of risk decision approaches
• Cumulative Risk Criteria vs. Scenario Criteria
• Continuing Examples

Day 4: Implementing LOPA

• Is the company ready for LOPA?
• What is the current foundation for risk assessment?
• What data is required?
• Will IPL’s remain in place?
• How are risk tolerance criteria established?
• When is LOPA used?
• The Bow-Tie Model
• Discussion: Typical implementation tasks and implementation barriers

Day 5: Using LOPA for other applications

• Risk-based Operator Training
• The credible design basis for Overpressure Protection
• Evaluate the need for Emergency Isolation Valves
• Incident Investigations
• Program Evaluation and General Discussion