Impacts of gas pipeline internal coating on system capacity at Ghana National Gas Plant, Atuabo

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August, 2015
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Pipelines play an extremely important role throughout the world as a means of transporting gases and liquids over long distances from their sources to the ultimate consumers. Transmission pipelines are made of steel and generally operate at pressures ranging from 500 to 1,400 pounds per square inch gauge (psig). Pipelines for gas transportation are coated primarily to ensure that the pipeline does not corrode. In addition to anticorrosion, some pipelines are internally lined typically with a liquid epoxy or Fusion Bonded Epoxies (FBE) system to enhance the flow characteristics of the natural gas or oil travelling through the pipeline. The main types of pipeline coatings in use today include coal tar enamel, polymeric tapes, fusion-bonded epoxy (FBE), spray-applied liquid coatings, and two- and three-layer polyolefin coatings. The main objective of this research was to determine impacts friction and transmission factors of both coated and uncoated pipelines have on flow rates. The AGA and Colebrook-White equations were both used to determine these impacts on system capacity. Using both AGA equations and Colebrook–White equations, it was observed that the coated pipe was able to transport 8.91% and 9.42% more flow rate Q respectively than the uncoated pipe. It is therefore concluded that decreasing the pipe roughness directly results in a throughput or efficiency increase in a pipeline. Thus, smoother pipe surface leads to increased flow capacity. Internal flow coating can also make a significant difference in reducing pumping or compression costs over the lifetime of the pipeline. These reduced energy costs can provide a financial payback within some years of service. Internal coating of steel pipe is also vital to ensure the long term integrity of the pipeline and reasonable long-term reliability.
A project submitted to the School of Graduate Studies Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the degree of Professional Master of Engineering with Management Oil and Gas Option.