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Paint/Protective Coatings Engineering: Internal Liner material...Help!

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    • CommentAuthorgfergus
    • CommentTimeAug 6th 2009
     permalink
    Does anyone have any experience with liner material for application on pipework with internal corrosion/erosion in a Methanol Regeneration System?

    Text:

    The pipes are designed to hold hot methanol and water in both liquid and vapour form.

    Normal operating conditions for the pipes:

    Temperature
    • Average temp - 172F
    • Max temp - 267.1F

    Pressure
    • Average internal pipe pressure - 5.4 PSIG
    • Max internal pipe pressure - 15 PSIG

    Acidity level
    • pH level of ~3.5-5.5

    Chloride level
    • 90000 – 120000ppm


    Process treatment in the pipes consists of:

    1) Oxygen Scavenger (sodium bisulphate)
    2) Scale Inhibitor (polymer based)
    3) Corrosion Inhibitor (organic)
    4) Defoamer (silicon polymer)

    Failure mechanisms/ Anomalies detected include:

    • Weld root corrosion
    • Pitting corrosion
    • Synergistic effect of erosion/corrosion
    • Impingement corrosion

    If anyone has experience with using an internal liner or lining material with applications similar to the above any feedback would be much appreciated.
  2.  permalink
    Internal liners are made of polyolefins (polyethylene or polypropylene). They effectively protect from internal corrosion of pipelines and also constitute a way for the rehabilitation of corroded pipelines. Liners are easy to install and result in time and cost savings. However, the main limitations of this type of product are:

    1.- Operating temperature. In general High Density Polyethylene (HDPE) can be used up to 194 F and polypropylene up to 230 F

    2.- Permeation. Some type of gases (such as crude oil volatile compounds) may pass through the polyolefin layer and accumulate in the anular space between the inner polyolefin plastic layer and the wall of the metallic pipeline.

    This liner technology do not present pressure constrains, since pressure resistance is provided by the host metallic pipeline.

    A good option is to contact suppliers and tell them about your particular case. Some of them are:

    http://www.unitedpipeline.com/content/125/installation_overview.aspx
    http://www.hebna.com/poly-solution.php
    http://www.subterra.co.uk/subline_sl.html
    http://www.murphypipelines.com/assets/downloads/swagelining/1098.pdf

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