New Century and Integrity Plus Blog

Under Pressure

Posted by Phil Tisovec on Jan 29, 2018 7:53:40 AM

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Why do we have pressure calculations and how do they relate to In-Line Inspections (ILI)? Let’s start with why. This comes down to three main reasons: PHMSA requirements, sorting through ILI report “noise”, and to estimate response time.

PHMSA Requirements

Within our industry, there are regulation differences between gas and liquid. However, both follow pressure-based response criteria where calculations are referenced. They have slightly different terminology, but the calculations are analogous, which equate to the estimated internal pressure when your pipeline will release product. Ultimately, these lead to a required need for action if the noted condition exists.  

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Sorting Through the ‘Noise’

In-Line Inspection reports are usually very long with lots of data to sort through, and it can be a daunting task trying to see the whole picture. You might be focused on one feature’s attribute, such as metal loss depth, when another feature’s safe operating pressure could be telling a different story. Calculating pressure values can help bring these potential threats together into a more cohesive and complete look at what is really going on in your pipeline.

Estimate Response Time

Pressure calculations can be used to determine when time-dependent threats such as corrosion need to be addressed. What initially may look like an anomaly needing to be dealt with immediately, may end up having a longer estimated response time. Or conversely, corrosion anomalies with relatively shallow depths may need attention before your planned re-inspection interval.

Now that we’ve explored why pressure calculations exist, we can consider how ILI results are involved. The simple answer is, they provide another level of analysis and context when reviewing ILI data, but it is helpful to understand their origin and if they can be trusted. Gaining this understanding in turn leads to better integrity planning and asset management.


Want to dive deeper into how and why pressure calculations are used during the ILI management process? Head on over to our free webinar, Decrypting Pressure Values Reported by In-Line Inspections, to learn about methods, example calculations and results being applied to real-life scenarios. And feel free to contact us to chat about how our ILI Services team can help your organization, as well as any training we can offer.

Topics: Integrity Management, ILI, In-Line Inspection, Pressure Calculations

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