PHMSA Gas Transmission (GT) Integrity Management
Time: 04/23/2014 04:56 PM

Protocol Item D.08

D.08 Dry Gas ICDA Direct Examination

For dry gas systems, verify that the operator (1) identifies locations where internal corrosion is most likely in each ICDA region and (2) performs direct examinations of those locations. [192.927(b), 192.927(c)(3), ASME B31.8S-2004, Section 6.4 and ASME B31.8S-2004, Appendix B2]

  1. Verify that the operator's plan defines criteria to be applied in making key decisions (e.g., identifying locations most likely to have internal corrosion, selection of examination tools) in implementing the direct examination stage of the ICDA process. [192.927(c)(5)(i)]

  1. Verify the operator has identified locations where internal corrosion is most likely to exist in each ICDA region and where electrolyte accumulation is predicted. [192.927(c)(3), ASME B31.8S-2004, Section 6.4.2 and ASME B31.8S-2004, Appendix B2.3]

  1. Verify the operator requires a direct examination for internal corrosion using ultrasonic thickness measurements, radiography, or other generally accepted measurement technique of those covered segment locations where internal corrosion is most likely to exist, and includes as a minimum, the following: [192.927(c)(3), ASME B31.8S-2004, Section 6.4.2, ASME B31.8S-2004, Appendix B2.3 and ASME B31.8S-2004, Appendix B2.4]
    1. A minimum of two (2) locations within each ICDA region within a covered segment,
    2. At least one location must be the low point (e.g., sags, drips, valves, manifolds, deadlegs, traps) nearest the beginning of the ICDA region and
    3. The second location must be further downstream within a covered segment near the end of the ICDA Region (The end of the ICDA region is the farthest downstream location where the ICDA model predicts electrolytes could accumulate based on the critical angle of inclination above which water film cannot be transported by the gas). [192.927(c)(2) and ASME B31.8S-2004, Appendix B2.3]
  1. If internal corrosion exists at any location directly examined, verify that the operator: [192.927(c)(3)]
    1. Evaluates the severity of the defect and remediates the defect per 192.933 (see Protocol E) [192.927(c)(3)(i)], and
    2. Either performs additional excavations or performs additional assessment using an allowed alternative assessment method [192.927(c)(3)(ii)], and
    3. Evaluates the potential for internal corrosion in all pipeline segments (both covered and non-covered) in the operator's pipeline system with similar characteristics to the ICDA region containing the covered segment in which the corrosion was found and remediates the conditions per 192.933. [192.927(c)(3)(iii)]
  1. Verify that the operator's plan contains provisions for applying more restrictive criteria for the direct examination when conducting ICDA for the first time on a covered segment [192.927(c)(5)(ii)]

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