Ask Your Mates Open Forum

Pipeline investigation

  • 1.  Pipeline investigation

    Posted 19 August 2019 22:31
    ​Good day mates

    Currently planning to asses the condition of our buried pipelines (MSCL, CI, AC) with the intent to scan the entire lengths using non-destructive technology.

    I'm leaning towards transient technology over acoustic technology. Has anyone had any experience to share with these technologies?


    Russell Uy
    Senior Asset Engineer

  • 2.  RE: Pipeline investigation

    Posted 21 August 2019 18:46
    ​Hi Russell,

    I hope everything is well there in Southeast Queensland.

    A couple years ago my team and I at Gold Coast Water led a project to conduct a pure technologies smart ball assessment on the Western Force Main (WFM), the Gold Coast's biggest sewer rising main at 900mm.  We tied the assessment to the Commonwealth Games Athletes Village development.  The WFM ran directly through the center of the village and we were able to get the developer to fund the assessment as due diligence. We assessed something like 2-3 Kilometres (if my memory is working).

    My experience thus far is that smart pigging is cost prohibitive considering the results and risks. The assessment was able to identify gas pockets at several locations where there were high points in the main.  However, a simple review of the As-Constructed profile drawings of the main would have identified the same high points. The assessment did not identify wall thickness or other condition anomalies. I believe their are other technology options available now that may have better results but they are even more costly and are still indicative only.  By indicative I mean they really only point you in the direction of pipe segments that will require more in depth assessment such as Ultrasonic Thickness (UT) testing. Also there are pretty big risks with the ball getting stuck or lost in the system. In our case with the WFM the treatment plant was the terminal point for smart ball retrieval. To say the plant operators were on edge with this assessment would be a drastic understatement. The risk of having to shut down the entire main was very real and would have been an absolute nightmare. Luckily all went well.

    I believe a thorough desktop investigation of the pipe alignment by a qualified RPEQ or CPENG, that considers environmental factors such as acidic soils, high points, potential major conflicts, would have yielded similar results as far as identifying the areas for exposing the main and conducting a UT test to determine wall thickness and get actual quantitative condition data.

    Personally I am a fan of strategically planning UT testing at points on the main spaced between 250 - 500 meters that capture different environmental conditions (such as varying soil conditions). Do this for say a 5,000 meter section of main and then apply a Mote Carlo analysis to the resulting condition data to get an overall condition score for the main as well as more granular condition scores for each segment. This is very cost effective and provides quantitative data that is more defensible when renewal is required.

    As with any technology there is an appropriate place and time for it.

    I have provided a list of what I see as pros and cons regarding inline smart pigging to assist with determining whether it is right for your main:
    • Good for mains with little or no records such as As-cons
    • Good for mains that are very difficult or unsafe to expose and access (i.e., segment with high ground water or passing under the M1)
    • Can cover very long lengths in one pass
    • Provides a good indicative overview of the main
    • The technology is really really cool!
    • Non destructive (well mostly see cons)
    • Does not require shut down of the main (well mostly see Cons)

    • Very costly operational expense (you can do a lot of UT tests and get actual quantitative condition data for that kind of money)
    • Requires a lot of logistical planning for entry point, exit point, and system management (more operational $)
    • May require alteration of the main to provide an entry or extraction point (non destructive can become destructive)
    • There are high risks associated with the ball getting stuck which can require extraction (again non destructive can become destructive)
    • Generally the smart ball assessment requires follow up UT tests to confirm  the indicative results (more operational $). 
    • It is difficult to justify a renewal based on a smart ball assessment alone.
    I am sure some smart pigging sales representatives will have a difference of opinion on this but this is my two cents based on my experience working from the utility side of things where budgets are tight and tolerance for risk is low.

    I hope this information is helpful.  Feel free to email me if you would like to discuss in more detail.


    Earl DuPriest

    Asset Management Program Manager

    Charleston Water System

    103 St. Philip Street | Charleston, SC 29403

    Tel: 843-727-7202

    Mob: 843-214-4310



  • 3.  RE: Pipeline investigation

    Posted 24 August 2019 19:08
    Dear Colleagues,

    I've been involved in Condition Assessment and Failure Investigation of pressure water pipes/pipelines for more than 30 years. As a consequence of this I have used, and been associated with large number of technologies, including acoustic and transient technologies. My biggest concern is the "resolution" of the techniques (averaging over many metres is of little value in my opinion), and that the techniques don't address the failure modes of coated steel, and asbestos cement pipes (as well as Cast iron). Additionally, there are concerns of verification and significant variability into input variables, which are required to interpret the signal outputs generated.

    The most important result for coated steel is minimum remaining wall thickness - not an average value!  For asbestos pipes I suggest that IPWEA Engineers read my LinkedIn post and also refer to EBMUD post comparing acoustic results and actual results - where correlation was less than 30%.

    There are better and probably less expensive ways of determining condition than either of these two techniques. ILIT, addressing the failure modes of these pipe materials.

    Philip Ferguson
    Principal Consultant ADE Consulting Group Pty Ltd