$200 ILI Anomaly
A $200 Anomaly Threshold
The mysterious title of this article hints at the path that all past articles have (hopefully) taken us down. Let’s take a quick look at those past articles.
The common thread among all of these disparate titles might not be apparent. They all point to better decision-making. Managing the risks of our inherently threatening assets and processes is more assured and more efficient when our decisions are informed by the best available information. That is the path being highlighted by these articles.
Which leads us now to one critical application of all that has been presented along this path. How to best address suspicious—but not critical—irregularities identified by inspections.
Say you’ve done a ILI and identified thousands of anomalies along a pipeline. You probably are compelled by regulations to repair/remediate some of these based on established criteria.
Once those are addressed, should you do more? That is generally left up to you, with consideration for regulatory warnings that you must ‘protect the integrity’, ‘minimize risks’, ‘ensure safety’, and other similar phrases. Attorneys will add phrases like ‘taking actions a prudent operator would’. These obviously do not provide specificity for decision making.
To gain that specificity, let’s add some formality to this decision process. Taking from ALARP, we can create a defensible framework from which to make these challenging decisions. Per ALARP, once we have attained a predetermined baseline level of safety, we are compelled to then take every risk reduction action until the cost of such action becomes ‘grossly disproportionate’ to the benefit derived. That quoted phrase is important.
Assume that, as a long-time practitioner of ALARP, your company has determined the break over into ‘grossly disproportionate’ to be a factor of 7. That is, your company is willing to spend up to $7 to avoid $1 of risk. You can use that to ‘back into’ an actionable level of risk.
Say an excavation with repair/remediation costs around $21K in area of this recent ILI and that each excavation can cover an average of 3 anomalies. Therefore, there is a cost of $7K per anomaly addressed. Using your company’s ALARP ‘grossly disproportionate’ factor, all anomalies generating an increment of $7k / 7 = $1K EL (EL=expected loss, a measure of risk) or more, should be addressed. That is, your GDF suggests that you spend up to $7k to avoid at least $1k of risk. So, only anomalies that expose you to $1k or more of risk, warrant remediation.
If you’re fairly certain you will be performing another integrity assessment in 5 years, that perhaps further suggests that each anomaly generating $200 EL per year or more should be addressed ($1,000 EL increase over 5 years = $200 EL increase per year). That can be your threshold for taking discretionary action on an anomaly[1]. This is a very powerful conclusion. With this, you now have, perhaps for the first time ever, an objective, defensible threshold for ‘when is enough, enough?’.
Having this threshold is a huge breakthrough. But you’re not quite done. You still have to identify which, among the thousands of anomalies, exceed your $200 EL threshold. You should begin by recognizing how each anomaly type and severity contribute to risk. For example, an external metal loss anomaly should impact many risk input variables including:
- CP effectiveness
- Coating condition
- Rupture potential
- Leak potential
- Leak vs rupture implications for consequence scenarios including leak detection/reaction, hazard zone generation, and others.
- Remaining life estimates for any time-dependent failure mechanism: ext corr, int corr, cracking
- Resistance to external-, internal-, intermittent-, etc, loadings
Crack-like indications, geometrical anomalies (eg, dents, ovalities, etc), stress concentrators, and all the other possible anomaly types will each have their own implications to future risk, if left unaddressed. Furthermore, their mere appearance in an inspection, whether subsequently addressed or not, also has implications to risk.
Don’t be intimidated. This rather challenging set of considerations can be set up in a basic software environment (eg, spreadsheet or desktop database) to automatically analyze thousands of anomalies, requiring little effort (once set up).
Once compete, the analyses not only shows which anomalies are actionable, it also provides a transparent, defensible trail of how you determined which are actionable. All stakeholders can see the rationale and conservatism used. This not only fulfills regulatory requirements (see P&M language in US IMP regs), but it is responsive to any other challenge to how your company is making such critical decisions.
So, the tools are now readily available whereby you can move away from old practices of debate and subjectivity that often made decision-making inefficient and inconsistent. Stay tuned for the next milepost along this rapidly maturing path.
[1] after ensuring that the baseline level of safety is still being achieved, of course