This paper details the challenges encountered in successfully treating this 45-year-old low- and highpressure
very sour gas gathering system in North Dakota. The existing gathering system has been
owned and operated by several companies over the lifetime of the piping, and corrosion mitigation was
not always a concern to each owner. Much of the low-pressure system was designed and installed in the
late 1950s and early 1960s. Access points for monitoring and treating corrosion were not considered in
the design and construction process. A result is that the lines have severe, localized metal loss in low
spots, low flow velocities, and few access points, which makes delivery of corrosion inhibitor,
maintaining line cleanliness, and monitoring the system difficult. The evaluation, modeling, treatment,
and monitoring processes used to assess system conditions, to design and implement a treatment
program, and to monitor corrosion are presented. The results of this nine year program include a
sustained, significant reduction in failures and associated costs and are detailed.