Under PHMSA’s regulations, which incorporate voluntary industry  consensus standards for managing the system integrity of gas pipelines,  operators must reassess their gas transmission pipeline segments for safety  threats overall at least every 10, 15, or 20 years (consistent with industry  consensus standards), depending on the condition of the pipelines and the  stress under which the pipeline segments are operated. 2.) About 2010, operators will be expected to  begin reassessing some segments of their pipelines for corrosion under the  7-year reassessment requirement while they are completing baseline  assessments of other segments—called “the overlap.”
It is important to note that the reassessment intervals under the industry  consensus standards, the 7-year reassessment requirement for corrosion,  and PHMSA’s regulations for time-dependent threats represent the  maximum number of years between reassessments. Baseline assessment findings conducted to date and the generally  safe condition of gas transmission pipelines suggest that the 7-year  requirement appears to be conservative. Most Operators Have Reported That Their Gas Transmission Pipelines Are Mostly Free of Serious Problems

Through December 2005 (latest data available), 76 percent of the operators  (182 of 241) reporting baseline assessment activity to PHMSA told the  agency that their gas transmission pipelines were in good condition and  free of major defects, requiring only minor repairs. 1.) Forty-four of these  operators have begun baseline assessments, and 37 of these 44 (84 percent)  told us that they found few safety problems that required reducing pipeline  pressure and performing immediate repairs in response to baseline  assessments in highly populated or frequently used areas. However, nationwide, these incidents are relatively rare. Further,  since operators, are required to identify and repair significant problems,  the overall safety and condition of the gas transmission pipeline system  should be enhanced before reassessments begin toward the end of the  decade. The maximum intervals of 10, 15, and 20  years are based on worst-case corrosion growth rates. However, operators expressed their uncertainty about whether  qualified direct assessment and confirmatory direct assessment  contractors will be available. Operators Report that Services and Tools Are Likely to Be Available for Reassessments

Thirty-seven out of 52 operators (71 percent), one in-line inspection  association, and all four inspection contractors that provide direct  assessment or in-line inspection tool services that we contacted told us that  the services and tools needed to conduct periodic reassessments will likely  be available to most operators. 3.) As a  result, operators might not be able to meet the reassessment requirement. The information provided by the operators that we contacted shows a  marked overall increase in assessment and reassessment activity in 2010 (a  16 percent increase over 2009 activity) and then a gradual decrease of  activity through 2012. Another reason for the  difference may be due to methodology. Rather, if  conditions warrant, an operator would be required to reassess a pipeline  segment as frequently as needed—perhaps even more frequently than  every 7 years. Scope and Methodology

To understand how the findings from operators’ baseline assessments  inform us about the need to reassess gas transmission pipelines at least  every 7 years, we reviewed the requirements of the Pipeline Safety  Improvement Act of 2002 and PHMSA’s implementing regulations. To determine the extent to which gas transmission pipeline operators and  local distribution companies will likely have the resources to reassess their  pipelines, at least every 7 years, we synthesized testimonial and  documentary evidence obtained from our discussions with (1) 52 operators  (as described above) and (2) pipeline assessment tool contractors, direct  assessment vendors, and industry associations on the prospective  availability of equipment, equipment operators, and data analysts to  interpret results.
Why GAO Did This Study

The Pipeline Safety Improvement Act of 2002 requires that operators (1) assess gas transmission pipeline segments in about 20,000 miles of highly populated or frequently used areas by 2012 for safety threats, such as incorrect operation and corrosion (called baseline assessments), (2) remedy defects, and (3) reassess these segments at least every 7 years. Under the Pipeline and Hazardous Materials Safety Administration's (PHMSA) regulations, operators must reassess their pipeline segments for corrosion at least every 7 years and for all safety threats at least every 10, 15, or 20 years, based on industry consensus standards--and more frequently if conditions warrant. Operators must also carry out other prevention and mitigation measures. To meet a requirement in the 2002 act, this study addresses how the results of baseline assessments and other information inform us on the need to reassess gas transmission pipelines every 7 years and whether inspection services and tools are likely to be available to do so, among other things. In conducting its work, GAO contacted 52 operators that have carried out about two-thirds of the baseline assessments conducted to date.

What GAO Found

Periodic reassessments of gas transmission pipelines are useful because safety threats can change. However, the 7-year requirement appears to be conservative because (1) most operators found few major problems during baseline assessments, and (2) serious pipeline incidents involving corrosion are rare, among other reasons. Through December 2005 (latest data available), 76 percent of the operators (182 of 241) that had begun baseline assessments reported to PHMSA that their pipelines required only minor repairs. These results are encouraging because operators are required to assess their riskiest segments first. Since operators are also required to repair these problems, the overall safety and condition of their pipelines should be enhanced before reassessments begin. In addition, PHMSA data suggest that serious gas transmission pipeline problems due to corrosion are rare. For example, there have been no deaths or injuries as a result of incidents due to corrosion since 2001. Of the 52 operators contacted that have calculated reassessment intervals, the large majority (20 of 23) told GAO that based on conditions identified during baseline assessments, they could safely reassess their pipelines for corrosion, every 10, 15, or 20 years--as industry consensus standards prescribe unless pipeline conditions warrant an earlier assessment. Sufficient resources may be available for operators' reassessment activities, but some uncertainty exists. For the most part, the 52 operators that GAO contacted expect to be able to obtain the services and tools needed through 2012. However, they expressed some concern about whether enough qualified vendors for the confirmatory and direct assessment methods (above-ground inspections followed by excavations) would be available. Industry associations and GAO attempted to determine the degree to which activity would increase from 2010 to 2012, when operators begin reassessing pipelines while completing baseline assessments. An industry effort showed an increase in assessment and reassessment activity, but GAO's showed a decrease. The reasons for the differences are not clear but may be due, in part, to differences in the operators contacted and the methodologies used in collecting this information.