North American Oil & Gas Pipelines

SEP 2018

North American Oil & Gas Pipelines covers the news shaping the business of oil and gas pipeline construction and maintenance in North America, including pipeline installation methods, integrity management innovations and managerial strategies.

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28 North American Oil & Gas Pipelines | SEPTEMBER 2 018 By Cole Morehead and Eric Germann API statistics show that a barrel of oil shipped by pipeline safely reaches its destination 99.999 percent of the time. 1 For natural gas, PHMSA recorded less than one "seri- ous" incident per 100,000 miles of distribution pipe- line in 2017. 2 While unlikely, incidents happen. When they do, the cause tends to be corrosion, base material/weld failures, or equipment malfunctions, according to PHMSA 3 . Getting to the root cause of problems and reducing safety risk is the purpose of pipeline integrity management, which includes periodic inline inspec- tions and non-destructive testing (NDT). Each system operator has its own inspection proce- dures, but smart pigs are generally run in 60- to 100- mile segments. The inline data is analyzed to identify anomalies that might indicate potential trouble spots that warrant excavation for additional inspection. That's where NDT service providers such as XCEL NDT LLC come in. Pig data locates a possible anomaly, but like an "in- dustrial doctor," it's up to the NDT technician to inves- tigate it, diagnose it and figure out why it occurred so the operator can take corrective action. Inspection be- gins with visual examination and progresses to apply- ing specialized techniques to assess a pipeline's overall health by analyzing a sampling of the soils, coating, base material, long seam welds and girth welds. External corrosion is a common problem on buried pipelines. Another serious related issue is stress corro- sion cracking (SCC), which is unpredictable, but can progress rapidly. Consequently, a major focus of NDT services is evaluating the effects of corrosion. Virtually all pipelines have cathodic protection to mitigate corrosion. NDT technicians use pipe-to-soil potential to measure cathodic voltage and specially calibrated probes to determine soil composition, mois- ture, pH and resistivity levels–all of which influence corrosion. Microbiologically-induced corrosion (MIC) sampling identifies corrosive bacteria and fungi in soils. This information on environmental conditions and pipe/soil chemical interactions at burial depth helps pipeline engineers remediate problems and opti- mize cathodic programs. PIPE INSPECTION METHODS Evaluating the structural integrity of the pipe itself starts with visually searching for mechanical damage, NDT Services Critical to Diagnosing Integrity Issues, Ensuring Safe Pipeline Operations

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