Secondary location classes

(I’m back.  Things still seem to be incredibly busy but I’m hoping to find enough time to resume reasonably regular posts here.)

I still haven’t finished the series of posts on location classification so it seems appropriate to resume with a brief overview of the secondary location classes.  To establish the basics:

Every point on a pipeline must have a primary location class (R1, R2, T1 or T2).  But there are some land uses and features that don’t fit neatly into those primary classes.  So AS 2885 has provision for secondary location classes that draw attention to these special locations.

Secondary location classes are optional – they only need to apply where they are relevant.  As noted previously, the main purpose of location classification is to help the safety management study identify and focus on areas of higher risk and in some cases to require increased risk reduction measures.  That applies equally to primary and secondary location classes.  If a secondary location class requires additional risk reduction then that overrides the requirements of the primary location class.

There are five secondary location classes (see Clause 4.3.5 of AS 2885.1-2007):

  • Sensitive (S)
  • Industrial (I)
  • Heavy industrial (HI)
  • Common infrastructure corridor (CIC)
  • Submerged (W)

That should all be pretty straightforward.  In subsequent posts I’ll expand a bit of the first four secondary classes.  There isn’t much to say about the W class because it doesn’t impose any particular requirements, other than the obvious need to ensure that the design is appropriate for the submerged (or equivalent) installation conditions.

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5 Responses to Secondary location classes

  1. Scott Mitchell says:

    Peter, I hope I am not repeating a question answered elsewhere on your blog. I am a new subscriber, so have not digested all the information available as yet. Some engineers that I am dealing with are of the view that only a single secondary location class (the most stringent applicable) can be applied to any location. I am of a differing view that the designer can apply multiple secondary location classes and apply the mitigation measures as appropriate. Logically, the more stringent mitigations will win out. In my view, any secondary location class not recorded runs the risk of future engineers (such as in the next 5year SMS review) misinterpreting the intent. I know this is probably a mute point, but I think it would be best for designers to be consistent in secondary location class applications because it sets the precedent for the pipeline. Would be interested in hearing your thoughts on this. Scott

    • petertuft says:

      Scott,

      I agree with you that multiple secondary location classes are possible in principle. Some SMS databases might have provision for only one (including my own!) but that doesn’t mean you can’t make a note somewhere if necessary. It’s not unusual for CIC to overlap with S, I or HI. On rare occasions you might even have CIC, S and I (eg. pipeline in a utilities corridor passing a childcare facility in a light industrial area). The requirements for CIC involve liaison with the other parties in the corridor and are of a different nature to those for the other location classes, so it’s not even as if one is more stringent and “trumps” the others. They are just different, and both need to be considered.

  2. Lynndon Harnell says:

    I believe that there is a case for a “Rural with CSG operations” secondary classification. These areas contains a higher (although transient) population density, and a higher level of gas-corporate (both APLNG and others) owned infrastructure such as gathering systems and the like. These systems have a high likelihood of ongoing and continual works over the lifespan of a transmission pipeline through the area, and there is the potential for a higher incidence of external interference threats. Such infrastructure does not have the characteristics of T1 as a primary classification. Similarly it does not meet the criteria for an (I) Industrial secondary classification. Therefore these areas should be R1 or R2 as a primary classification but they certainly are not plain vanilla R1 or R2.

    These considerations then in turn affect the consideration of puncture resistance factor B and excavator size to apply. One method could be to atempt to link selection of factor B in some form to the secondary classification in this case.

    As regards excavator size, general earthworks contractors predominantly have excavators ranging up to 30t with a few 35t machines available. They simply do not have the rationale to justify the hassle of a police permit in order to move such a machine around on roads. More specialised contractors (such as those that might construct a highway, GPF or dam) commonly have machines up to 45t. A 55t excavator is a fairly rare beast. There is however at least one contractor in Oz that will rent you a 75t excavator, but AS2885 calcs do not go to that size machine. Hence some degree of exatrapolation would be required.

    Furthermore the effect of both GP and Tiger teeth can be mitigated by the mandating of cutter bars or bucket without teeth within a CSG operational area. I believe that within a CSG operational area, tiger teeth should be banned excepting under rigorously controlled circumstances.

  3. petertuft says:

    Lynndon,

    I’m not keen on proliferating specialist location classes – there might be no end to that if we started. Location classes are mainly meant to reflect population density, and the threat level associated with higher population density is a secondary consideration. I agree completely that CSG operations areas introduce a significantly higher threat level, but that should be handled by the SMS without having to introduce another location class. In my experience most CSG areas seem to be R1, with occasional R2, and very occasional T1 where someone routes a pipeline past a camp or maintenance/operations base. If a workshop or facilitator can’t figure out that certain land uses (not just CSG operations) introduce special threats then they are in trouble anyway.

    Also agree completely that tiger teeth should be banned in CSG areas. But can you ban chain trenchers? They are perhaps an even bigger threat.

    • Lynndon Harnell says:

      Peter
      I believe that it is the intent of AS2885 that the PRIMARY location class that is about population density.
      The SECONDARY lcoation class is about other considerations, and indeed could be a useful means of collecting a set of conditions for input into the SMS. After all we have secondary classes such as industrial, heavy industrial, etc.
      Btw, I have never been able to get my head around the classification of CSG gas plants as “Heavy Industrial” which some companies use. The term conjures up a comparision with ship buiding or perhaps a refinery, which stretches credibility!
      of course you cannot ban chain trenchers in CSG areas, not can you ban PE ploughs which are starting to be used. I think they have to be managed procedurally, Excavation Permits and the like..Of course the problem is much more severe of our PE pipeline cousins, as just about anything will chew through PE.

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