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WSG was contacted by one of our ILI partners, TD Williamson, for the purpose of providing extensive support services for the ILI campaign of an 8” x 5.2km liquid butadiene pipeline for Shell Singapore. WSG’s scope of work included supply of fully rated 8” pig traps (launcher & receiver), piping tie-ins, displacement & complete purging of the pipeline with N2, and pumping N2 to propel the pigs (including the intelligent pigs) during the ILI campaign.

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WSG was selected after an extensive technical qualification process, due to the detailed technical requirements of the butadiene pipeline, lasting exactly a month. The contract was awarded to WSG in end-May 20114, and work started immediately, in order to meet the shutdown window of Oct-Nov 2014. Extensive pre-engineering works were carried out by our in-house piping specialist, to ensure all the piping tie-ins were correctly measured-up and isometrics were produced and submitted to client, for in-house fabrication. All these works were provided free, as part of our value-added services; obviously to the delight of our client. 

Most important was the need for complete control of the pumping parameters, at the launching end, to ensure a steady pigging velocity of ≈ 1m/s, which was crucial for optimum data quality for the ILI runs. As WSG has in-house pigging specialists, the parameter control was achieved without any problems. The project team worked together with the ILI contractor to identify the minimum pressure requirement, and then ensured the corresponding flowrate was maintained, for the ideal 1m/s pigging velocity.

At the receiving end, the N2 was vented off to atmosphere, through WSG’s portable silenced vent system. The pressure at the receiving end was controlled, via a 2”choke valve, to maintain a good ΔP between the launching & receiving stations.

Four pig runs were performed by the ILI contractor, two of which were intelligent pigs. Data recorded during the runs were of good/acceptable quality, and the ILI campaign was thus completed successfully.