HAZOP for Existing Facilities

When is a HAZOP necessary for an existing facility?

Many industrial plants are successfully operated for decades. During this time, pumps are replaced, piping is modified, control systems are modernized, or entire sections of the plant are expanded. Every single change has a clear goal: to operate the plant reliably, efficiently, and in a future-proof manner. Over time, however, a crucial question often arises: Does the plant’s safety assessment still accurately reflect its current condition?
It is particularly evident in older existing plants that the original design and the plant’s current condition do not always fully correspond. Documentation has been updated over the years, components have been replaced, and processes have been modified. Often, there is no complete HAZOP, or it only partially reflects the plant’s current condition.

This issue comes into focus, at the very latest, when major renovations are planned, a safety inspection is due, or government agencies and experts require documentation.

Not all changes are the same

In practice, terms such as “replacement,” “modernization,” and “retrofit” are often used interchangeably. From a safety perspective, however, these measures can have different implications.

Replacing a pump with a technically equivalent model or replacing a measuring device as part of routine maintenance is often different from integrating an additional heat exchanger, adjusting operating parameters, or making changes to safety-related control functions.

The more extensively a change affects existing processes or safety functions, the more important it becomes to consider its impact on the safety of the entire plant. There is no one-size-fits-all answer to what measures are required. Rather, a project-specific assessment is necessary that takes into account both the technical changes and the applicable regulatory framework.

Does that mean a full HAZOP must always be conducted? The short answer is: No.

Not every change requires a complete reassessment of the entire system.

It is often sufficient to conduct a targeted analysis of the affected area of the plant and to assess the impact on adjacent systems. A partial HAZOP, for example, may be an appropriate approach when changes are limited to clearly defined areas.

The situation may be different if numerous modifications have accumulated over many years or if there is no comprehensive safety assessment of the entire facility. In such cases, a more comprehensive analysis may be advisable in order to evaluate the facility’s current condition in a structured manner. The decisive factor here is not the scale of an individual change, but rather its impact on the facility’s safety concept.

The biggest challenge

In our experience, the real challenge with existing facilities often lies not in conducting the HAZOP itself, but rather in the preparation phase.

• Are the existing R&I flow diagrams up to date?
• What changes have been implemented in recent years?
• Which safety features have been modified?
• What documentation is actually still available?

Particularly in the case of systems that have evolved over decades, information is often scattered across various documents or exists solely in the form of employees’ practical knowledge.

For this reason, a HAZOP for existing facilities often begins with a joint assessment of the current state of the facility. The goal is to document the actual condition of the facility as completely as possible and to use that information to determine an appropriate scope for the analysis.

A HAZOP relies on people’s knowledge

No documentation can replace the knowledge of those who operate a facility on a daily basis.

That is why successful HAZOP workshops bring together different perspectives: operations, maintenance, process engineering, instrumentation and control, and project planning. Only through joint discussion can a complete picture of the plant emerge.

Particularly with existing facilities, it is often the case that many years of operational experience provide valuable insights that would not be apparent from the plans alone.

Our Approach at CONENGA

Every existing plant has its own history. That’s why there is no one-size-fits-all solution.

Our initial goal is to work with the operator to understand what the actual task entails:

• What changes were made?
• What documentation is already available?
• What question should be answered?
• What scope of examination is reasonable and appropriate?

Based on this, we support our clients from the preparation and facilitation of the HAZOP through to the implementation and clear documentation of the results.

In doing so, we place particular emphasis on a pragmatic approach. Our focus is not on conducting the most extensive analysis possible, but rather on providing a structured and transparent assessment that is tailored to the specific facility and project.