Despite pipelines offering the safest and most efficient means of transporting hydrocarbons, they are not immune to failure and therefore require routine inspection and maintenance. Different types of pigs, i.e. solid, plug-like devices launched into a pipeline and driven by fluid, represent the most thorough and direct means of performing corrosion inspection and maintenance work such as de-waxing. Pigs have traditionally been launched from dedicated surface facilities (platform or onshore), but can also be launched from subsea pig launchers installed temporarily on the seabed to facilitate the pigging operation. The latter is a developing technology and is becoming increasingly utilized in the offshore oil and gas industry, especially in deep water and marginal field developments. This paper provides detailed information of the evolving technology of pig launching systems, with particular emphasis on subsea systems and their associated challenges. A qualitative methodology for evaluating different pig launching systems is established, based on cost, technical feasibility, safety and environmental risk.
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