Condition modifiers in BowTiePro are factors that influence the likelihood or effectiveness of risk scenarios within a LOPA (Layer of Protection Analysis) assessment.

These modifiers help organizations account for additional operational or environmental conditions that may impact the overall risk calculation.

Condition modifiers are commonly used for:

Using condition modifiers helps create more realistic and accurate LOPA assessments.

Opening the LOPA Diagram

To configure condition modifiers:

  1. Open the LOPA module from the top navigation menu.
  2. Open an existing LOPA assessment.
  3. The LOPA diagram will display:
    • Threats
    • Controls
    • Hazard
    • Consequences

Opening the LOPA Control Details Screen

Condition modifiers are configured through the control/barrier settings.

To open the control details:

  1. Click the small information (i) icon below a control/barrier.
  2. A barrier information popup will appear.
  3. Click Edit.

You will be redirected to the LOPA Control Details screen.

Configuring Control Values and Modifiers

Inside the LOPA Control Details screen, you can configure how the control behaves within the LOPA calculation.

Available configuration options include:

These values influence the effectiveness of the control and contribute to the final LOPA calculation results.

After entering the required values:

  1. Review the configuration carefully.
  2. Enter supporting justification if needed.
  3. Click Save.

Understanding PFD in Condition Calculations

PFD (Probability of Failure on Demand) represents the likelihood that a control or safeguard may fail when required.

Lower PFD values indicate stronger and more reliable safeguards, while higher values indicate weaker protection layers.

Accurate PFD values are important for:

Best Practices for Condition Modifiers

When configuring condition modifiers and control values:

In BowTiePro LOPA assessments, controls are assigned PFD (Probability of Failure on Demand) values to calculate how effective a safeguard is at reducing risk.

PFD values represent the likelihood that a control may fail when required during a hazardous event.

Accurate PFD values are essential for:

Opening the LOPA Diagram

To configure control PFD values:

  1. Open the LOPA module from the top navigation menu.
  2. Open an existing LOPA assessment.
  3. The LOPA diagram will display:
    • Threats
    • Controls/barriers
    • Hazard
    • Consequences

Opening the LOPA Control Details Screen

PFD values are configured within the control settings.

To open the control details:

  1. Click the small information (i) icon below a control/barrier.
  2. A barrier information popup will appear.
  3. Click Edit.

You will be redirected to the LOPA Control Details screen.

Configuring the PFD Value

Inside the LOPA Control Details screen, locate the Define PFD field.

To configure the value:

  1. Ensure Use In Calculation is enabled.
  2. Select the required Calculation Type.
  3. Enter the desired PFD value in the Define PFD field.
  4. Add justification or supporting notes if required.
  5. Click Save.

The configured PFD value will now be used in the LOPA calculation process.

 

Understanding PFD Values

PFD values determine how reliable a control is during demand situations.

General interpretation:

For example:

Organizations should use validated engineering or operational data when assigning PFD values.

Best Practices for Configuring PFD Values

When configuring PFD values:

Why Accurate PFD Values Matter

Incorrect PFD values can lead to:

Properly maintained PFD values improve both safety and compliance.

In BowTiePro LOPA assessments, the overall consequence value represents the final calculated risk associated with a specific consequence after considering threats, controls, enabling factors, and condition modifiers.

This value helps users understand whether the remaining risk level is acceptable or if additional protection layers are required.

Viewing Consequence Values

To review consequence values:

  1. Open the LOPA module.
  2. Open an existing LOPA assessment.
  3. Navigate to the LOPA Details page.
  4. Scroll down to the Consequence section.

The consequence section displays the consequence linked to the selected threat and top event.

Understanding How Consequence Values Are Determined

The final consequence value is influenced by several elements within the LOPA assessment, including:

BowTiePro combines these values to determine the remaining risk level after safeguards are applied.

Reviewing Threat and Consequence Controls

Controls directly affect the calculated risk value.

Threat controls reduce the likelihood of the event occurring, while consequence controls reduce the severity or impact after the event occurs.

Each control can include:

Understanding the Final Result

The overall consequence value helps users determine whether:

The value is continuously updated based on the inputs configured throughout the assessment.

Viewing Consequences in the LOPA Diagram

Users can also visually review consequences directly within the LOPA diagram.

The diagram provides a simplified visual representation of:

This helps users better understand how each protection layer contributes to overall risk reduction.

Best Practices

When reviewing overall consequence values:

Accurate configuration ensures more reliable LOPA calculations and better risk management decisions.

After configuring threats, controls, enabling factors, and condition modifiers, BowTiePro calculates the final Layer of Protection Analysis (LOPA) results.

These results help users determine whether existing safeguards reduce risk to acceptable levels.

Viewing LOPA Results

To review LOPA results:

  1. Open the LOPA module.
  2. Select an existing LOPA assessment.
  3. Review the assessment list and detailed analysis screens.

The LOPA List page provides a quick overview of all assessments, including:

Understanding the “Met?” Status

The Met? column indicates whether the calculated risk level meets the configured acceptance criteria.

Possible outcomes include:

A “No” result typically indicates that:

Reviewing the LOPA Diagram

Users can visually review the assessment using the LOPA diagram.

The diagram displays:

This visual representation helps users understand how each safeguard contributes to risk reduction.

Reviewing Detailed LOPA Information

Detailed calculation-related information is available within the LOPA Details page.

The details page includes:

This information is used by BowTiePro to calculate the final assessment result.

Understanding Risk Reduction

LOPA calculations evaluate how effectively controls reduce the likelihood or impact of hazardous events.

Risk reduction is influenced by:

Higher-quality and independent safeguards generally improve overall results.

Using Results for Decision Making

LOPA results help organizations:

Best Practices

When reviewing LOPA results:

Acceptance criteria and Safety Integrity Levels (SIL) are important concepts within Layer of Protection Analysis (LOPA).

BowTiePro uses these concepts to help organizations determine whether existing safeguards reduce risk to acceptable levels.

What Are Acceptance Criteria?

Acceptance criteria define the maximum level of risk considered acceptable for a specific scenario.

Within a LOPA assessment, BowTiePro evaluates whether the calculated residual risk meets these predefined criteria.

If the calculated risk exceeds acceptable limits, additional safeguards or protection layers may be required.

Reviewing Acceptance Status

Users can review acceptance status directly from the LOPA assessment list.

The Met? column indicates whether the scenario satisfies the configured risk acceptance requirements.

Possible results include:

Understanding SIL Levels

SIL (Safety Integrity Level) is a measurement used to evaluate the effectiveness and reliability of safety functions and protection systems.

SIL assessments help determine how much risk reduction is required for hazardous scenarios.

Higher SIL requirements generally indicate that stronger or more reliable safeguards are needed.

How BowTiePro Supports SIL-Related Analysis

BowTiePro uses LOPA calculations to help users understand whether current safeguards provide sufficient protection.

The assessment considers:

These elements collectively contribute to overall risk reduction.

Reviewing Risk Reduction in the LOPA Diagram

The LOPA diagram provides a visual representation of how controls reduce risk between threats and consequences.

The diagram helps users identify:

Reviewing Detailed Assessment Information

Detailed LOPA calculation information is available within the LOPA Details page.

The details page includes:

This information supports risk evaluation and SIL-related decision making.

Understanding “Met” and “Not Met”

A scenario marked as Met generally indicates that:

A scenario marked as Not Met may indicate that:

Best Practices

When evaluating acceptance criteria and SIL-related assessments:

Properly configured LOPA assessments help organizations improve safety, strengthen risk management, and support informed operational decisions.

Overview

Creating a hazard is the first step in building a BowTie analysis in BowTiePro. A hazard represents a risk scenario and forms the foundation for defining threats, consequences, and controls.

Steps to Create a New Hazard

1. Go to the Hazards Section

2. Click “New Hazard”

Hazard Details Fields Explained

On the Hazard Details screen, you need to fill in the following fields:

3. Select Location

👉 This determines where the hazard will be grouped

4. Enter Reference

👉 This helps identify the hazard in lists and reports

5. Enter Hazard

👉 This defines the risk source

6. Define Top Event

👉 This represents the point where control over the hazard is los

7. Select Type

👉 This helps classify the severity or category

8. Add Hazard Remarks (Optional)

9. Set Next Review Date

👉 This helps schedule periodic reviews

10. Select Categories

👉 These help classify the hazard for reporting and filtering

Final Step: Save the Hazard

Once all required fields are filled:

Creating a hazard in BowTiePro is a straightforward process that sets the foundation for your entire risk analysis. Once created, you can proceed to define threats, consequences, and controls to complete the BowTie model.

Overview

Once a hazard has been created, you may need to update its details such as description, top event, or classification. BowTiePro allows you to easily edit hazard information through the Hazard Overview screen.

Steps to Edit a Hazard

1. Go to the Hazards Section

2. Open a Hazard

3. Click “Edit”

Updating Hazard Information

On the Hazard Details screen, you can modify the following fields:

Location

Reference

Hazard

Top Event

Type

Hazard Remarks

Next Review Date

Categories

Saving Changes

After making updates:

From the Hazard Overview screen, you can also:

Editing hazard details ensures that your risk data remains accurate and up to date. This is an important step in maintaining an effective BowTie analysis.

Overview

In BowTiePro, threats and consequences define how a hazard can lead to an event and what outcomes may occur. You can quickly add multiple threats or consequences along with controls using the Quick Add feature.

Accessing the Quick Add Screen

1. Open a Hazard

2. Click “Quick Add”

Adding Threats

By default, the Threats tab is selected.

3. Enter Threat Description

4. Add Controls for the Threat

5. Select Control Type

6. Set Effectiveness

Adding Multiple Threats

Adding Consequences

7. Switch to “Consequences” Tab

8. Enter Consequence Description

9. Add Controls for Consequences

Saving the Entries

The Quick Add feature allows you to efficiently create multiple threats and consequences along with their controls. This helps build a complete BowTie model quickly and accurately.

Overview

Controls are critical elements in BowTiePro that help prevent threats from causing a top event or reduce the impact of consequences. Controls are linked directly to threats and consequences and can be added during the risk modeling process.

How Controls Are Structured

In BowTiePro:

Adding Controls

1. Open a Hazard

2. Click “Quick Add”

3. Add Controls While Creating Threats

Under the Threats tab:

4. Add Controls for Consequences

Viewing Controls

After saving:

Controls are linked within these items and contribute to the BowTie structure.

Managing Controls

To update controls:

Controls are essential for managing risk in BowTiePro. By linking controls to threats and consequences, you can build a strong and effective risk model that helps prevent incidents and reduce impact.

Overview

Escalation factors are conditions that can reduce the effectiveness of controls in a BowTie model. Managing escalation factors is important to ensure that controls continue to perform as intended and risks remain properly managed.

What Are Escalation Factors?

An escalation factor is something that can:

Example:

Why Escalation Factors Matter

Even if controls are defined:

Escalation factors help identify:

How Escalation Factors Are Used in BowTiePro

In BowTiePro:

Managing Escalation Factors

To manage escalation factors:

1. Identify Potential Weaknesses

2. Add Escalation Factors

3. Apply Additional Controls (if required)

4. Review and Update Regularly

Escalation factors help ensure that controls remain reliable under real-world conditions. By identifying and managing these factors, you can strengthen your overall risk management strategy in BowTiePro.

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