More on augers

When I wrote the previous post on auger damage I’d been remiss in not properly reading a report that had been sent to me some time earlier.  There was some very nice work done by the old Gas & Fuel Corporation (of Victoria) in 1983.  I’ve made the report available in two parts – the body (1.9 MB), and the appendices (4.5 MB) which include tabulated results and photos of pipe damage.

(The work also included some tests on excavator damage but that’s been superseded by more recent research and already incorporated into AS 2885.)

I was particularly interested in the discussion on page 5 of the text, dealing with the attitude of the rig operators.  In particular they claimed they could tell immediately from the “feel” of the machine when they had hit a buried pipe, and that “a pipeline … could not be punctured by a simple mistake”.  All reassuring stuff, but it doesn’t completely rule out the possibility of auger failures because there is always the prospect of naive or stupid operators.

The tests used two types of auger rig, apparently representative of equipment used in Victoria in 1983.  One was a truck-mounted pendulum auger, the other a “fixed” auger on the back of a tractor.  Both look slightly archaic by 2010 standards but I suspect that modern equipment has pretty similar basic characteristics.

I’d be interested in any feedback on whether there might be a need to update this work, or whether the equipment and tests from 1983 remain valid today.

(Thanks to APA for permission to make the report available.  Gas & Fuel Corporation was split up and no longer exists but APA inherited large parts of it including the transmission pipeline system.)

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4 Responses to More on augers

  1. Mark Coates says:

    I can see this work still having relevance today, albeit with an updated approach plus materials.

    As we know (and as the report states), these tests were done using different grades of steel than may be used in similar services today, and the tests were completed with the pipes at lower pressures.

    Perhaps a more accurate reflection of what can happen would be to undertake these test with a pipe section at closer to the current MAOP’s seen today – maybe a sample of higher transmission pressures and lower reticulation pressures. The key would be to create a test environment which is realistic (for today) plus safe.
    Another consideration would be to look at the social aspects of why augers hit and damage pipelines. If there is significant effort required to severly damage a pipeline, then are the operators under pressure to get the job done based on time and cost, and therefore their experience and judgement is clouded?

  2. petertuft says:

    I don’t think that internal pressure is very relevant to this sort of damage. I have a hazy recollection that the excavator damage research done at UWA showed that it had negligible influence even in that situation, where one might expect the internal pressure to provide some sort of support against the denting and deformation caused by the tooth attempting to penetrate. For an auger which just grinds away at the steel surface I think internal pressure would have even less relevance. That is to some extent supported by the Gas & Fuel photos, which show cutting rather than denting.

    Having said that, high-thrust drill rigs such as larger HDDs can cause pipe deformation as well as cutting. But testing a pressurised pipe is a very fraught undertaking even when the pressurising fluid is inert (eg. water).

    Agree completely about the need for social research into why these incidents happen in the first place. That’s a task for the EPCRC Research Program 4 (public safety & security of supply), and work will be starting in a small way next year on the knowledge and attitudes held by the perpetrators of pipeline damage.

  3. Michael Malavazos says:

    Peter,

    Not 100% sure how the equipment tests were used to derive formulae in standard for calculating potential for pipeline damage, nor am I sure how generic the formulae are but if type of equipment is critical to this then yes I think there is a case to review and close out this issue in light of new equipment.

    • petertuft says:

      Michael,

      There was extensive and rigorous research done at Uni of WA several years ago and it forms the basis for the Appendix M of AS 2885.1 (on penetration resistance). But it was largely restricted to excavators, with a half-baked extension to rippers that is of limited use.

      Currently there are no formulae at all for augers, nor am I sure that they would be of much use. There is great deal of semi-subjective judgement involved in estimating the consequences of equipment impact. Excavators vary greatly in capacity to damage pipe and the UWA research was valuable in providing some numbers to underpin the judgements. But for augers it seems to me that the Gas & Fuel work provides enough information to make judgements without further quantification. Pole augers are unlikely to penetrate a steel pipe, but it is possible in unusual circumstances (mainly a rig operator who persists despite indications of having hit something). If penetration occurs we can readily estimate the hole size.

      Having said all that, I agree that there might be some merit in a survey of equipment types in current use, and any further research might depend on what that reveals. There is a bit of low-key discussion going on about such a survey.

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