Introduction

In the hydrocarbon transportation industry, maintaining the integrity and reliability of pipeline systems is essential to ensure operational safety and minimize environmental risks. Globally, the conditions surrounding these systems have changed significantly due to urban expansion, encroachment into safety zones, and, in some cases, acts of vandalism. These dynamics increase threats to system integrity, especially in pipelines transporting fuels.

Recently, we worked with a client in Argentina to conduct a comprehensive risk assessment on part of their pipeline system. The primary objective was to optimize safety and operational reliability, reduce spill risks, and improve response capability in the event of potential leaks. To achieve this, an interdisciplinary approach was adopted, combining various advanced methodologies, including a critical zone prioritization system, fluid dynamic simulations, HAZOP analysis, and LOPA analysis.

Identification of High Consequence Areas (HCAs) through Interdisciplinary Workshops

The first step in achieving the proposed objective was to identify High Consequence Areas (HCAs), where the impact of a leak would have greater repercussions, either due to proximity to populated areas, water bodies, or critical industrial facilities. For this analysis, a matrix-based scheme was used to weigh various key factors such as:

• Proximity to urban populations;
• Potential spill volume;
• Proximity to water bodies;
• Distance to pumping stations and valves;
• Intersections with railways and roads.

The scheme was developed and debated in an interdisciplinary workshop involving personnel from maintenance, processing, asset integrity, safety, environment, and GIE staff as risk analysis specialists. Each variable was weighted according to its relevance to the operational context, and a scoring system was established to prioritize the most critical pipeline segments.
This interdisciplinary process was essential to ensure that all possible interactions between pipeline operations and their surroundings were considered, providing a solid foundation for the subsequent phases of the project. The results of the workshop served as a guide to identify critical points where efforts needed to be concentrated.

Fluid Dynamic Simulations and Failure Scenario Analysis

Once critical areas were identified, a comprehensive fluid dynamic analysis was conducted. This allowed the modeling of the pipeline system’s behavior under various failure scenarios and evaluated the consequences of breaks along the most vulnerable segments.

Specifically, scenarios were simulated for each type of transported fluid. These simulations provided key insights into how the system would react to a leak and how mitigation measures could influence spill magnitude. The main findings were as follows:

1. Stable liquids: It was found that a rapid intervention in the event of a rupture can significantly reduce the spilled volume. If pumping is stopped within the first 2 minutes after detecting the rupture, the spill volume can be reduced by up to 90%. This highlights the importance of having an efficient detection system and remote valve closure.
2. Volatile liquids: For these products, the dynamics are more complex. While stopping pumping partially reduces product release, the generalized system decompression continues to feed gas leaks. This indicates that, in addition to early pumping intervention, additional measures such as strategically located remote block valve closures are required to minimize the released volume.

The analysis also revealed that initial pressure profiles significantly impact spill volumes. Ruptures occurring in low-pressure sections tend to result in smaller spill volumes, underscoring the importance of carefully managing operational pressure levels.
Risk Assessment Using HAZOP and LOPA

To complement the findings of the fluid dynamic simulations, a risk analysis was performed using two widely accepted methodologies in the industry: HAZOP (Hazard and Operability Study) and LOPA (Layer of Protection Analysis).

The HAZOP analysis allowed for a detailed examination of operational risks associated with different critical points in the system and identified potential deviations from normal operating conditions that could lead to incidents. This analysis was crucial in detecting points where a combination of adverse operational conditions could significantly increase the risk of rupture or leakage.

On the other hand, the LOPA analysis helped identify and evaluate existing and required protection layers to mitigate the detected risks. These layers include:

• Leak detection systems;
• Remote block valve closures;
• Emergency response procedures.

By combining the HAZOP findings with LOPA, it was possible not only to identify the system’s most vulnerable points but also to determine the effectiveness of proposed mitigation measures. For example, the LOPA analysis confirmed that for pipelines transporting volatile liquids, remote valve closures in critical areas are essential to reduce the impact of leaks, as system decompression is a predominant factor in gas release.
Implementation of Improvements and Action Plan

The resulting action plan included several improvements in both detection systems and valve operations. These improvements were based on the conclusions of the fluid dynamic and risk analyses and focused on reducing response times to leaks and optimizing the system’s capacity to mitigate the consequences of a rupture.

Some of the recommendations provided are detailed below:

• Install a leak and/or rupture detection system, including localization.
• Install actuators on block valves located at the inlet and outlet of pipelines to minimize the initiation times of their closures, activating closure remotely.
• Install actuators to allow remote closure of block valves proposed based on the risk analysis.
• Design a Contingency Plan to control spills or leaks, including the management of alarms generated by the leak detection system.
• Train operating personnel to ensure they have the appropriate knowledge to make informed decisions and act effectively in the event of a rupture emergency.

Conclusion
The interdisciplinary approach adopted in this project, which combined a critical area determination system, fluid dynamic simulations, HAZOP and LOPA risk analysis, was key to significantly improving the reliability and safety of the pipeline system. The results not only helped reduce the risks associated with potential leaks but also optimized daily operations and emergency responses.

One specific conclusion drawn from the complete analysis was that some installed valves did not significantly reduce the simulated spill volumes. However, they constituted an attraction for vandalism. Thus, removing these valves would mean a reduction in the risk level.