conference report | Pipeline coating 2013
results in a minimum 95% coverage. The system uses white, yellow, red and blue pigments
to identify the different pipe sizes, with the predominant pipe size left untreated (black) to minimise pigment consumption.However, Koebsch said with the additional cost for colouring the pipes amounting to only around $1 per m2
of pipe surface, it is not a costly technique. Salzgitter Mannesmann Forschung coating
Above: Petrobras is using micro- nized pigment- ed PE to colour code the different pipe sizes to avoid mis-identifica- tion
and FAST EPP systems achieve very good bonding and will allow simple conversion of existing coating lines. Intecsea materials engineer Irving Annan explained that with some subsea offshore infield flowlines today operating at 100˚C there is a requirement for thin coatings that provide the required mechanical and corrosion protection while also promoting effective heat loss. “If we can decrease the temperature of the pipeline we can decrease the rate of corrosion,” he said. Annan said in a recent project undertaken by Intecsea
for an internally CRA-clad carbon steel flow line operating at between -20 and +100˚C on the seabed at 13˚C, it was found that none of four FBE systems considered could fully satisfy the design requirement of a 25 year lifetime. This was attributed to the reduced adhesion performance associated with traditional methods of raising Tg, an area he said needed to be addressed with novel chemistries that stiffen the polymer backbone rather than increasing crosslink density. Petrobras mechanical engineer André Koebsch
explained how the company had developed a system of colouring 3LPE pipes with spray applied micronized pigmented polyethylene within its Brazilian coating plants to simplify identification of pipes. “During construction, if we have a 100km pipeline we will have at least 800 pipes in different thicknesses. It is difficult to be sure we have the right pipe,” he said. Colouring the different pipes provides clear differentia- tion but applying a pigment to the top surface of a 3LPO pipe is not a simple task. “The first idea was to put a stripe on the pipe but PE gives problems of adhesion so it is easy to abrade the colour,” he said. To overcome the adhesion challenge and achieve full surface coverage for easy identification, Petrobras developed a micronized pigmented resin that is applied via spray nozzles immediately after the polyolefin extrusion stage. Koebsch said the residual heat in the topcoat is sufficient to achieve effective fusion of the pigment to the surface and
44 PIPELINE COATING | May 2013
specialist Dr Markus Betz detailed an investigation the company undertook into unexpected cracking and spalling of a PP top coat soon after low temperature installation of a 3LPP during the winter of 2007/8. The investigation revealed that current low temperature impact testing was unable to simulate the damage, sug- gesting that some failure was occurring either in storage or during installation. The company developed a new coating system for
pipes installed at low temperatures comprised of a 3LPE followed by an HDPE rough coat and PP protective top coat (with the option of a PA top coat for very demanding applications). Betz also detailed the modified impact testing procedures the company developed to assess the new coating system. Richard Schertzer, market development specialist at Madison Chemical, presented a field joint application case study of a 3LPE pipeline of 40 and 48-inch diameter (maximum operating temperature 80˚C) operated by Kuwaiti Oil Company. Surface preparation included SSPC-SP10 blasting of the steel and a flame treatment of the PE followed by a light SSPC-SP7 brush blast prior to spray application of the 750-1,000 micron protective coating. Cure to inspection time for the system at 25˚C was between 10 and 12 minutes, he said, enabling a daily production rate of 40-50 joints.
Click on the links for more information: ❙
www.amiplastics.com ❙
www.jotun.com ❙
www.hempel.com ❙
www.nov.com/tuboscope ❙
www.shawcor.com ❙
www.stopaq.com ❙
www.intecsea.com ❙
www.petrobras.com ❙
www.salzgitter-mannesmann-forschung.de ❙
www.madisonchemical.com
About the conference: Pipeline Coating 2013 took place in Vienna, Austria, in February. The full conference proceedings, including 20 papers, are available here
bit.ly/16BQpV8 For more information about the 2014 conference, click here
bit.ly/10AzslO
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