Gas transmission companies are trying to convince federal regulators to use integrity management guidelines to determine when pipe needs to be replaced outside high consequence areas (HCAs). The 2011 pipeline safety law requires the Pipeline and Hazardous Materials Safety Administration (PHMSA) to decide whether an expansion of the integrity management (IM) program beyond HCAs would eliminate the need for the class location system.
PHMSA issued a proposed rule in August and extended the comment deadline once. The proposed rule raised inter-related issues: 1) whether the IM program should be extended beyond HCAs, 2) if so, should new HCAs be designated based on IM principles or class location, 3) if class locations are to remain, should transmission companies be given new leeway to maintain pipe even if the class location in an area increases.
The 2002 IM program specifies inspection, repair and reporting requirements for pipeline segments in high population areas. Operators use a calculation – called the pipeline impact radius (PIR) – to establish which segments are in HCAs. That calculation is dependent on the maximum allowable operating pressure (MAOP) of the pipeline and its diameter. Of the 18,000 miles in the Energy Transfer Partners system, for example, 2,000 are in class locations 2 and 3, and 800 are in HCAs.
The class location system divides areas on each side of a pipeline up to 660 feet into four classes (1-4), depending on population density, and prescribes operating pressures and pipeline thicknesses within each category, to provide a margin of safety. As population inside the class increases, pipelines may have to reduce pressure or replace pipe.
The industry believes the class location requirement to replace pipe is often unjustified. Class location does not rely on the operating character of the pipeline. That can overestimate or underestimate the consequences of a pipeline accident, according to the Interstate Natural Gas Association of America (INGAA). PIR adjusts as pipeline pressure and size change.
Beyond complaints that class location leads to unnecessary pipe replacement, the industry is also concerned that PHMSA is using class locations to qualify what it is calling “moderate consequence areas” governed by a new Integrity Verification Process (IVP). There companies would have to verify characteristics such as MAOP and construction materials for what are called “grandfathered” pipelines – i.e. – those pre-1970 for which MAOP was never established.
INGAA is concerned PHMSA is using both class location and PIR in the IVP. That is because the agency wants to define an MCA as a “non-HCA pipe in class 1, 2 or 3 or a class 1 with one structure within the PIR.”
Eric Amundsen, vice president, Technical Services, Energy Transfer Partners, said giving pipelines the ability to use IM procedures to evaluate pipeline segments outside HCAs, in class location areas, is the “logical, appropriate and clearly intended direction set when the IM regulations were developed 10 years ago. He notes PHMSA provided a precedent when it finalized a rule in 2008 which allows pipelines to maintain existing MAOPs without replacing pipe in an area whose step up in class location would otherwise dictate a pipe change out. Operators can apply for and receive a special permit which often allows the MAOP to stay steady, but can impose IM-related operations and reporting criteria.
INGAA says pipe should not have to be replaced in a class location area where population increases if the pipe’s MAOP has been properly validated, and meets a “fit for service” criteria, which would probably require the company to run an inline inspection tool through a much longer stretch of pipeline than the much shorter stretch of pipe that would have to be replaced under the “change-out” process prescribed by the class location system.