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  Title Safe criterion for eliminating SCC by metal removal
  Author(s) Dr Jung Ma and Michael Rosenfeld  
  Abstract Stress corrosion cracking (SCC) is an environmental cracking condition that can affect buried steel pipelines exposed to specific environments that are influenced by factors associated with the characteristics of the coating system, soil type, and cathodic protection. The crack management program implemented by pipeline operators may provide for grinding or buffing out SCC discovered on the pipe body. The regulation 49 CFR ยง192.713(a) provides for repairs shown by reliable engineering tests and analyses to permanently restore the serviceability of the pipe. ASME B31.8-2003 and later editions allow repair of SCC by grinding to a smooth contour with metal loss not to exceed what is allowed for corrosion.

Therefore, regulations and standards give no concrete specification for maximum grinding dimensions along either dimension of an SCC colony except that the burst pressure calculated from its size must equal or exceed the operating pressure multiplied by a suitable safety factor (SF). ASME B31G-2009 and later editions recommend a minimum SF of 1.25, consistent with the recognized practice of reducing pressure to 80% of recent maximum operating pressure in some repair situations. In light of compelling safety concerns for field personnel, certain details are explored in this paper to provide more detailed guidance for the SCC grinding process.

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