Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.
Issue link: http://mp.epubxp.com/i/123600
M AT E R I A L M AT T E R S Continued from page 19 construction, and operating and maintenance plans and procedures. These special conditions include several actions intended to manage threats that can lead to external and internal corrosion. To ensure quality control of the coating process, for instance, one of the conditions calls for the application of a corrosion-resistant coating to the steel pipe to be performed according to a coat- 20 MATERIALS PERFORMANCE May 2013 ing application quality control program that addresses pipe surface cleanliness standards, blast cleaning, application temperature control, adhesion, cathodic disbondment, moisture permeation, bending, minimum coating thickness, coating imperfections, and coating repair. A condition addressing internal corrosion sets a basic sediment and water (BS&W;) limit of 0.5% by volume and re- quires BS&W; testing results to be reported to PHMSA in the annual report, along with a report of upset conditions that cause BS&W; level excursions above the limit. The special conditions also call for normal pump discharge temperatures to remain at or below 120 °F (49 °C). If the temperatures exceed 120 °F, TransCanada must prepare and implement a coating monitoring program for these areas using ongoing direct current voltage gradient (DCVG) or alternating current voltage gradient (ACVG) surveys or other testing to demonstrate the integrity of the coating. To provide early management of external corrosion threats during operations, another condition requires the initial cathodic protection (CP) system to be operational within six months of placing a pipeline segment in service. TransCanada must perform interference surveys over the entire Keystone XL pipeline within six months of placing the pipeline in service to ensure compliance with NACE International standards SP0169 2 and SP01773 for interference current levels. If interference currents are found, the special conditions direct TransCanada to determine if there have been adverse effects on the pipeline and mitigate such efforts as necessary. Additionally, TransCanada must complete corrosion surveys within six months of placing a CP system in operation to ensure adequate external corrosion protection per NACE SP0169. The corrosion surveys also will address the proper number and location of CP test stations, as well as AC interference mitigation and AC grounding programs per NACE SP0177. At least one CP test station must be located within each high consequence area (HCA) with a maximum spacing between test stations of 0.5 mile (0.8 km). The special conditions also require a close-interval survey (CIS) to be performed on the pipeline within one year of the pipeline in-service date. The entire pipeline also must be capable of passing inline inspection (ILI) tools, and a baseline ILI using a high-resolution magnetic flux leakage tool must be performed within three years of a pipeline segment NACE International, Vol. 52, No. 5