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  • 1.  Cleaning and Relining Pipes vs. Replacement

    Posted 07-26-2018 09:47 AM
    A local town has 80 year old cast iron pipes used for water distribution. Does it make any sense to clean and reline the pipes or should they be replaced entirely? Does anyone have experience with older water systems using cast iron pipes? And what is a realistic life span?

    Carmela Roberts P.E., M.ASCE
    Roberts Engineering Group LLC
    Hamilton NJ
    (609) 586-1141

  • 2.  RE: Cleaning and Relining Pipes vs. Replacement

    Posted 07-27-2018 04:22 PM
    Edited by Tirza Austin 07-27-2018 04:21 PM
    The City of Fort Worth, TX faced a similar decision during the early 1980's.  A record freeze and more than 7,000 line breaks during the Christmas holidays made the decision an easy one.  Ductile Iron and PVC became the new standard.  As streets were scheduled for reconstruction, the water lines were replaced.  I can't imagine spending money trying to extend the life of a system that has already served well beyond any expected service life.

    James Anderson, MASCE
    Anderson Consulting
    North Richland Hills, TX

  • 3.  RE: Cleaning and Relining Pipes vs. Replacement

    Posted 07-28-2018 02:09 PM
    In some circumstances, lining is the only practical method to restore the usefulness and life of a cast iron pipe.  Cleaning is always necessary followed by the insertion of a reputable lining material.  The circumstances could be when a line is in a busy street with multiple utilities in close proximity to the water line or when a line of buildings would be endangered by the excavation to replace the line .  Lining has been used to extend the useful life of cast iron pipe by 25-50 years.

    Harold Dungan P.E., M.ASCE
    PRESIDENT-H2Oaks Consulting LLC
    H2Oaks Consulting LLC
    Maxwell IN

  • 4.  RE: Cleaning and Relining Pipes vs. Replacement

    Posted 07-28-2018 02:11 PM
    ​HI Carmela:

    I have been involved with 1/2 dozen projects involving relining of old cast iron pipes. Some of the projects have been in service for more than 20 years.  Most of the pipes relined were installed in the 1890s and early1900's. Each of the projects were successful at restoring flow capacity and improved water quality to the areas served.

    The lining process was selected because the cost of replacement was high due to being in relatively high traffic areas (i.e.: in state highways, highly commercialized areas, significant number of other utilities in the area, etc.).  The lining process itself has a relatively high cost, so, there would be a few things you might like to consider before selecting it like: the host pipes should be without any significant history of breaks, the soil should be known to be generally not "highly corrosive", anything that might cast doubt on the condition of the existing pipe barrel.

    There are other trenchless restoration processes that have become available recently.  I haven't used any, but, some appear to be able to be used in instances where the pipe barrel may be in question. 

    Hope this is some help to you.

    Bart Clark , PE
    Warren CT

  • 5.  RE: Cleaning and Relining Pipes vs. Replacement

    Posted 07-28-2018 02:12 PM
    Edited by Tirza Austin 07-28-2018 02:11 PM
    Years ago, I served as a regional engineer for the Ductile Iron Pipe Research Association (DIPRA). I bet I handled dozens of questions similar to yours. The best answer we came up with is "it depends." On what? Does the pipe have an internal or external corrosion problem? You don't indicate which is the case in you problem statement. If it is an external corrosion problem, pipe replacement is usually indicated. If it is an internal corrosion problem (tuberculation), then pipe cleaning and relining may be possible if the wall thickness has not been reduced by more than 25%. Study of some representative pipe coupons should tell the tale. Cleaning and relining of old cast iron pipe is fairly commonly done for sanitary sewers, but I am aware of several instances where it has successfully been done on water lines as well. Cleaning and relining of cast iron is generally less than half the cost of pipeline replacement, so I would suggest that you carefully consider this option before leaping into a pipeline replacement program Willy Nilly. DIPRA has an extensive list of water utilities with cast iron pipe more than 100 years old and still in service, so don't just assume that an 80 year old cast iron pipeline doesn't still have many years of useful life remaining.

    Lawrence Magura P.E., D.WRE(Ret.), F.ASCE
    Lake Oswego OR
    (503) 638-4207

  • 6.  RE: Cleaning and Relining Pipes vs. Replacement

    Posted 07-30-2018 10:04 AM
    Edited by Tirza Austin 07-30-2018 10:03 AM
    Lining can be effective if there are no collapsed or badly broken sections where the flow area is already reduced.  Also, the act of cleaning the pipe, in preparation for lining, can cause some existing damage to get worse.   If you have to perform repairs before lining a DI pipe of this age, you will find that performing repairs can be difficult since the pipe will be brittle and will have a tendency for adjacent sections to split.  However, a liner will reduce the pipe diameter and, correspondingly, the capacity.  Thus, Pipe Bursting may be the better option because it will eliminate issues caused by collapsed or damaged pipes.

    Andrew Scott P.E., M.ASCE
    District Hydraulic Engineer
    Virginia Departement of Transportation
    Suffolk VA