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Fibreglass Reinforced Plastic Water Mains

  • 1.  Fibreglass Reinforced Plastic Water Mains

    Posted 09 May 2019 02:06
    Hi all
    Does anyone have any experience with Fibreglass Reinforced Plastic (FRP) trunk water mains?  At Upper Hunter Shire Council we are planning for the installation of a DN200 trunk main and GRP is one of the material options.  Max head pressure will be about 250m as we pump over a section of the local mountain range.  Are there any concerns over early failure or wear?  Are there any learnings that can be shared?
    Chris Agosto
    Upper Hunter Shire Council

  • 2.  RE: Fibreglass Reinforced Plastic Water Mains

    Posted 12 May 2019 20:28
    ​Hi Chris,

    My experience with GRP being used for water mains is not extensive but I have seen it fail in a number of gravity sewer and storm drain applications while working for the city of Gold Coast. The failures were generally delamination caused by jet rod cleaning and in less frequent cases scour due to high velocity flows. These failures resulted in very expensive fixes that could have been avoided by choosing a more resilient product such as HDPE or PVC. I would not recommend GRP for pressurized mains (based on 25+ years of water/sewer experience). We were able to include product risks as a selection criteria in our material option analysis to overcome the perceived financial benefits of GRP. This helped put cheaper materials such as GRP (that had not yet stood the test of time) at the back of the list. You will be hard pressed to find a data set on GRP longevity that is older than 50 years and that to me is a significant risk. I would strongly recommend HDPE, PVC, or DICL as the stock standard materials for most standard size water mains (say DN50-300). I am sure a GRP manufacturer representative will probably crucify me for this post and offer a litany of relevant excuses. I am also sure all of the excuses will be valid.  However, I am not a fan of using public utility and rate payers money as a testing ground for unproven materials. As an added caveat I would pose the question, "How familiar are your O&M crews with repairing and maintaining GRP?".  The answer is most likely, not at all, which opens up a whole other can of worms regarding risk.  Hope this input is helpful.


    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: Fibreglass Reinforced Plastic Water Mains

    Posted 13 May 2019 22:57
    Hi Chris
    Not going to crucify anyone here. There is no need but I think your view point and experience are very narrow.
    I have been a composites engineer for 30 years and have advised and designed GRP/PE/PVC and Steel pipe systems for potable water in NZ and Australia for that long.
    Flowtite Norway developed continuous wound GRP pipe in the 1950's and have manufactured and sold it around the world for a range of applications including potable water. There is 50,000km of pipe between DN300 and DN4000 installed around the world and at least half of it is for potable water.
    Long term testing has been undertaken by Flowtite for over 40 years and it is the long term properties of the pipe that are used for design (stiffness and pressure)
    By contrast HDPE pipe was first introduced to the Aust/NZ market in the late 1970's and not widely adopted until the the 1990's for potable water.
    PVC pipe was introduced in the 1970's and has had its own share of installation and design issues.
    Ductile iron concrete lined pipe is a relatively new product only available from the 1980's. It has very little in common with the cast iron pipe and fittings designed and manufactured during the 1800's.
    Get independent advice on your pipe choice and please do not base your choice on one or two failures. Every pipe material has failures and the resons are often as varied as the number of projects.

  • 4.  RE: Fibreglass Reinforced Plastic Water Mains

    Posted 15 May 2019 18:02
    ​Hi Douglas,

    I appreciate and respect your opinion. However, several of your statements were not entirely accurate. DICL for instance has been in use since the early 1920's, a quick google search will verify this.  I may be bragging a little here but the city of Charleston, where I currently work, was one of the first utilities to use DICL.  We still have some of that original pipe in operation, with no plans of replacing it due to its inherent longevity and stellar service history. As far as HDPE, I would recommend researching some of the case studies on pipeline resilience coming from the NZ earthquakes. HDPE pipe survived intact and operable while other materials sheared, cracked, and or dis-jointed. Does GRP/FRP have a place as far as pipeline infrastructure? Absolutely! Is it the right pipe for non standard applications such as excessive head (nearly double the standard in Chris's case)? If you are a smart risk manager, probably not. Just my humble opinion.


    Earl DuPriest

  • 5.  RE: Fibreglass Reinforced Plastic Water Mains

    Posted 15 May 2019 22:46
    Hi Earl

    Acknowledge that Kubota in Japan and one of the German pipe manufacturers produced ductile iron pipe from the 1890's.
    It is generally accepted that Ductile Iron pipe were introduced into water supplied in the USA from the 1950's (see paper below)
    Rajani, Balvant; Kleiner, Yehuda (2003). "Protecting ductile-iron Water Mains: What protection method works best for what soil condition?". Journal (American Water Works Association). 95 (11): 110–125. doi:10.1002/j.1551-8833.2003.tb10497.x
    You may have pipe that you think is ductile iron  in Charleston but I would be  checking its manufacture before stating that.

    Regarding Earthquake resistance as one of the engineers involved in pipeline investigations after the Christchurch May 2010 earthquake we found that the ability of any  pipe material to withstand ground movement was based on the bedding and backfill. Poorly installed pipe of all materials from HDPE  to Concrete failed in due to poor backfill and ground support.
    Christchurch had several GRP pipe lines that survived the earthquake and sizes were between DN750 and DN1200, in some cases the pipe was only thing golding concrete anchor blocks and structures in the ground. Immediate repair of damage was achieved with local fibreglass fabricators. In most cases these were  boat builders using materials they had on hand.
    In several cases ductile iron fittings were repaired using fibreglass bandages to get the network operational until permanent replacement fittings could be found.
    As a result of the experience of the earthquake Christchurch City Council accepts GRP pipe for their network where it is economical AND they have ensured that their own staff inpect any pipe material  installation to ensure installers follows the instructions to the letter.

    Excessive head. Just talk to the hundreds of power station owners around the world that insist that GRP pipe is used for anything over DN500(20") and 16 Bar.
    There are hydro penstocks in operation in earthquake prone locations (Norway, NZ and Sth America) that prefer a mechanically jointed system that has flexibility over a steel system that has a higher installed cost and a higher maintenance cost.

    Just the humble facts.


  • 6.  RE: Fibreglass Reinforced Plastic Water Mains

    Posted 16 May 2019 17:44
    ​Hi Douglas,

    As an open minded engineer and asset manager I appreciate all informed perspectives and opinions.  I certainly appreciate yours in this instance and applaud your persistence in advocating for GRP/FRP.  Based on all of the other comments in this thread, which all appear to be based on public sector personal experience with GRP/FRP, I reckon you have a long way to go convincing public utilities that it is the material with the least risk and best long term cost benefit.  I wish you the best of luck in this very daunting challenge.


    Earl DuPriest

  • 7.  RE: Fibreglass Reinforced Plastic Water Mains

    Posted 15 May 2019 18:03
    ​I have little direct knowledge of FRP pipes
    but I know from working with composites it is possible to get any property you want
    there are literally endless combinations of manufacturing processes, resins, reinforcement type's
    fillers  etc that can be used to create anything from dog bowel to a spaceship.

  • 8.  RE: Fibreglass Reinforced Plastic Water Mains

    Posted 15 May 2019 18:03
    It may have niche uses, but I think that there are quite a few of us who share similar experiences to Earl's with FRP in applications like Chris's. They are not the exception. Then add to that the likelihood of damage by locators when potholing with pressure equipment and the proposition certainly becomes marginal. We won't be using any more of it because doing so increases risks over the life of the asset well beyond any economic advantages.

    Shaun Johnston
    Manager Water & Waste Water
    Burdekin Shire Council