PHMSA Gas Transmission (GT) Integrity Management
Time: 11/24/2014 04:48 AM

Frequently-Asked Question FAQ #158

FAQ-158: Use of Historical Operating Conditions for ICDA

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Question: Must historical operating conditions be considered, or only current operating conditions, when using ICDA?

Answer: Historical conditions must be considered. The ICDA process is designed to identify areas where internal corrosion may have occurred, largely due to the fact that an electrolyte is/was present. Direct examinations are then conducted in those areas to determine whether internal corrosion has, in fact, occurred. The fact that an electrolyte is not present under current operating conditions may not mean that internal corrosion does not exist if electrolytes were introduced under previous operating conditions. For at least the first application of ICDA, then, considering historical conditions could be important. Of course, other information that confirms a lack of internal corrosion in areas where electrolyte could have been present historically (e.g., in-line inspection results, results of pipe replacement/examination) could alleviate the need to consider historical conditions. Operators should assure that there has been an opportunity to detect internal corrosion that may have occurred in the past, or should look for it during their initial ICDA.

These Frequently Asked Questions (FAQs) are intended to clarify, explain, and promote better understanding of the pipeline integrity management rules. These FAQs are not substantive rules and do not create rights, assign duties, or impose new obligations not outlined in the existing integrity management regulations and standards. Requests for informal interpretations regarding the applicability of one or more of the pipeline integrity management rules to a specific situation may be submitted to PHMSA in accordance with 49 C.F.R. 190.11.
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