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Laboratory study on the use of coupons to monitor cathodic protection of an underground pipeline

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OSTI ID:512035
; ;  [1]; ;  [2]
  1. ARCO Exploration and Production Technology, Plano, TX (United States)
  2. Alyeska Pipeline Service Co., Anchorage, AK (United States)
This paper presents the results of a four year laboratory program to determine the correlation between the potential of a pipeline coating defect and a cathodic protection (CP) coupon buried in the same environment. The factors evaluated include exposed steel area, geometry, distance from CP anodes, and temperature. Buried pipelines and electrically bonded CP coupons experience similar effects from CP systems and interference currents (e.g., Telluric and stray). When it is impractical to correct for voltage drops in pipeline potential measurements by disconnecting all current sources, CP coupons may be used to ensure that adequate cathodic protection has been achieved. Disconnecting coupons from the pipe removes IR-drop and mixed potential errors from coupon potential measurements. This testing was designed for application to the Trans Alaska Pipeline. Site specific engineering evaluations are recommended for application of these results to other pipelines.
OSTI ID:
512035
Report Number(s):
CONF-970332--
Country of Publication:
United States
Language:
English