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Damage Mechanism Assessments: Are Your PSM and AIM Managers Connecting?

Process Safety Management 

Damage Mechanism Assessments: Are Your PSM and AIM Managers Connecting?

It's time to start talking. Learn how you can use Damage Mechanism Assessments to get Process Safety Managers and Asset Integrity Managers communicating effectively. 

From 1996 to 2015 the oil, gas and chemical sector experienced a significant number of mechanical integrity failures that resulted in individual insurance claims in excess of $50 million USD. A 2017 insurance study from IChemE Hazards analyzed these losses and discovered:

  • 70% of failures were caused by pipework corrosion

  • 70% of failures occurred under normal operating conditions

The study concluded that failure to identify potential damage mechanisms and implement inspection programs is considered a fundamental issue underlying most of the losses.

Under normal operating conditions the prevention of a loss of containment incident is mechanical integrity, implemented through initial design and construction, and controlled with an inspection and maintenance program.  If you consider the safety barrier diagram (Figure 1), mechanical integrity is a preventative barrier. 

The responsibility for this barrier clearly lies with the asset management department, but there is an overlap with the process safety department when you consider the full barrier diagram, specifically the right-hand side of Figure 1.

Given the large number of significant incidents relating to normal operating conditions, it is clear that some operators are suffering from underlying issues: asset integrity or process safety. The following discusses how a Damage Mechanism Assessment/Review (DMA/R) can not only improve the effectiveness of inspection programs but provide valuable input for your process safety team.

Bowtie - Loss of containment under normal operating conditions
Figure 1: Bow Tie Diagram - Loss of Containment Under Normal Operational Conditions

Damage Mechanism Assessment/Review (DMA/R)

In our experience, many inspection programs are based on prescriptive, time-based, visual inspection and thickness measurements. However, these approaches have potential pitfalls, including:

  • A lack of a technical basis for the inspection, most commonly failing to inspect and/or test for unanticipated damage mechanisms
  • An overabundance of thickness measurements, seemingly in the “hope” of finding damage
  • Insufficient resources resulting in backlogs or inadequate time to analyze the results needed to optimize inspections and nondestructive testing (NDT)
  • Minimal correlation between the risk of failures and the extent and frequency of inspections

How can a DMA/R eliminate these issues?

A Damage Mechanism is defined as a mechanical, chemical, physical or other process, that can lead to damage. Examples include corrosion (uniform, localized and pitting), stress corrosion cracking (SSC), erosion, embrittlement, thermal-related failures and more. A DMA/R is a systematic analysis process that is designed to determine credible damage mechanisms for pressure-containing equipment such as process vessels, heat exchangers, process piping and storage tanks. Based on the chemicals being processed, the operating conditions, materials of construction and environmental external aggressors, the process predicts the type of damage, the likely damage rates and the most susceptible locations.

Asset Integrity Benefits of a DMA/R

The information collected and analyzed during a DMA/R will greatly improve the chances of:             

  • Testing in the right locations and using the appropriate approach
  • Developing an efficient testing program
  • Developing robust Integrity Operating Windows (IOWs), which are fundamental to life expectancy estimates and CAPEX planning
  • Improving turnaround management for fewer surprises, shorter downtimes and reduced frequency

Process Safety Benefits of a DMA/R

A DMA/R can also bring benefits to the process safety team during Process Hazard Analysis (PHA) studies by:

  • Ensuring that normal operating conditions are given due consideration in safety studies
  • Understanding the application and basis for asset integrity management (AIM) programs
  • Enhancing the understanding of likely loss scenarios including volumes, locations, phases and rates
  • Assisting with loss of containment scenario planning including locations, detectability, isolation and emergency response
  • Defining integrity KPIs and interpreting trends
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