255.939 Reassessment intervals.

An operator must comply with the following requirements in establishing the reassessment interval for the operator's covered pipeline segments.#

An operator must establish a reassessment interval for each covered segment operating at or above 30 percent SMYS in accordance with the requirements of this section. The maximum reassessment interval by an allowable reassessment method is seven years. If an operator establishes a reassessment interval that is greater than seven years, the operator must, within the seven-year period, conduct a confirmatory direct assessment on the covered segment, and then conduct the follow-up reassessment at the interval the operator has established. A reassessment carried out using confirmatory direct assessment must be done in accordance with section 255.931 of this Part. The table that follows this section sets forth the maximum allowed reassessment intervals.#

(1)Pressure test or internal inspection or other equivalent technology. An operator that uses pressure testing or internal inspection as an assessment method must establish the reassessment interval for a covered pipeline segment by:#

(i)basing the interval on the identified threats for the covered segment (see section 255.917 of this Part) and on the analysis of the results from the last integrity assessment and from the data integration and risk assessment required by section 255.917 of this Part; or#

(ii)using the intervals specified for different stress levels of pipeline (operating at or above 30 percent SMYS) listed in ASME/ANSI B31.8S, section 5, table 3 (as described in section 10.3 of this Title).#

(2)External corrosion direct assessment. An operator that uses ECDA that meets the requirements of sections 255.901 through 255.951 of this Part must determine the reassessment interval according to the requirements in paragraphs 6.2 and 6.3 of NACE RP 0502 (as described in section 10.3 of this Title).#

(3)Internal corrosion or SCC direct assessment. An operator that uses ICDA or SCCDA in accordance with the requirements of sections 255.901 through 255.951 of this Part must determine the reassessment interval according to the following method. However, the reassessment interval cannot exceed those specified for direct assessment in ASME/ANSI B31.8S, section 5, table 3.#

(i)Determine the largest defect most likely to remain in the covered segment and the corrosion rate appropriate for the pipe, soil and protection conditions.#

(ii)Use the largest remaining defect as the size of the largest defect discovered in the SCC or ICDA segment.#

(iii)Estimate the reassessment interval as half the time required for the largest defect to grow to a critical size.#

An operator must establish a reassessment interval for each covered segment operating below 30 percent SMYS in accordance with the requirements of this section. The maximum reassessment interval by an allowable reassessment method is seven years. An operator must establish reassessment by at least one of the following.#

(1)Reassessment by pressure test, internal inspection or other equivalent technology following the requirements in paragraph (a)(1) of this section except that the stress level referenced in subparagraph (a)(1)(ii) of this section would be adjusted to reflect the lower operating stress level. If an established interval is more than seven years, the operator must conduct by the seventh year of the interval either a confirmatory direct assessment in accordance with section 255.931 of this Part, or a low stress reassessment in accordance with section 255.941 of this Part.#

(2)Reassessment by ECDA following the requirements in paragraph (a)(2) of this section.#

(3)Reassessment by ICDA or SCCDA following the requirements in paragraph (a)(3) of this section.#

(4)Reassessment by confirmatory direct assessment at seven-year intervals in accordance with section 255.931 of this Part, with reassessment by one of the methods listed in paragraphs (1) through (3) of this subdivision by year 20 of the interval.#

(5)Reassessment by the low stress assessment method at seven-year intervals in accordance with section 255.941 of this Part with reassessment by one of the methods listed in paragraphs (1) through (3) of this subdivision by year 20 of the interval.#

(6)The following table sets forth the maximum reassessment intervals. Also refer to Appendix 14-E.II for guidance on assessment methods and assessment schedule for transmission pipelines operating below 30 percent SMYS. In case of conflict between the rule and the guidance in the appendix, the requirements of the rule control.#

An operator must comply with the following requirements in establishing a reassessment interval for a covered segment:#

Assessment method | Pipeline operating at or above 50% SMYS | Pipeline operating at or above 30% SMYS, up to 50% SMYS | Pipeline operating below 30% SMYS Internal Inspection Tool, Pressure Test or Direct Assessment | 10 years (*) | 15 years (*) | 20 years (**) Confirmatory Direct Assessment | 7 years | 7 years | 7 years Low Stress Reassessment | Not applicable | Not applicable | 7 years+ ongoing actions specified in § 255.941.#

* A confirmatory direct assessment as described in § 255.931 must be conducted by year 7 in a 10-year interval and years 7 and 14 of a 15-year interval.#

** A low stress reassessment or confirmatory direct assessment must be conducted by years 7 and 14 of the interval.#