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21 NACE INTERNATIONAL: VOL. 56, NO. 3 MATERIALS PERFORMANCE MARCH 2017 Information on corrosion control and prevention ously collected data should be evaluated for acceptable accuracy. In addition, with much of the pipeline located in low-lying, swampy areas near the coast, Chapman found that an 11-mi (17.7-km) stretch of the surveyed pipeline included no touch points from the start to the end, making a complete survey impossible. "Good structure attachment is always critical," Chapman says, noting that mod- ern technologies such as global position- ing systems (GPS) are making it easier than ever to conduct such tests—even in delicate areas like a U.S. Gulf Coast swamp. "We now live in an era where GPS allows good mapping of data," Chapman explains. "Think of pipeline surveying as geo-spatial. The pipe stays in the same place. So do test stations, rectif iers, and anode beds. We will touch all of them repeatedly over time. Mapping the data has always been necessary. Now it's easier than ever to do, and to check." But even today, some pipeline maps are inaccurate or incomplete. This can lead to diff iculties in locating not only the pipelines, but also the CP system ele- ments. "We f ind it very important to obtain accurate GPS coordinates on all surveys, so that future surveys corre- spond appropriately over the years of new surveys," Ames says. While acknowledging that current industry cost pressures pose challenges, Chapman warns that the existing NACE standard includes an emphasis on quality that should not be overlooked. "People are trying to reduce the amount of time it takes to do the survey, reduce the dollar bid they give clients, and reduce the investments they put in," Chapman says. "Surveys must be done over every single foot of the pipeline. Someone needs to be there to make sure. Corners shouldn't be cut." "There's a f ine line to walk, but if you follow the standard, it's clear what needs to be done," he adds. Contact Cal Chapman, Chapman Engineering—email: cchapman@chapman. engineering. References 1 M. Ames, C. Chapman, "How NOT to Do Close-Interval Potential Survey," presented at NACE Central Area Conference 2016, New Orleans, LA, 2016. 2 NACE Standard SP0207-2007, "Performing Close-Interval Potential Surveys and DC Sur- face Potential Gradient Surveys on Buried or Submerged Metallic Pipelines," (Houston, TX: NACE International, 2007). —Ben DuBose