Appendix A – Blade Report – Reliability Based Assessment of Pipeline Class Changes

Underground gas transmission pipelines are classified according to the presence of human populations in their proximity. These classifications are governed by PHMSA regulation (49 Code of Federal Regulations (CFR) Section 192.5) and industry standards. Operations, maintenance and integrity management requirements and acceptable operational conditions are more stringent with increasing class designations. Over time, specific sections of Class 1 pipelines may be re-classified as Class 3 with increase of population near such sections. With such reclassification, the maximum allowable operating pressure (MAOP) over the entire pipeline may have to be reduced, the reclassified sections may have to be replaced with new pipe, or enhanced pipeline integrity management approaches will have to be used to obtain a “Special Permit” for operating at the original MAOP…

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