SELECTION OF GAS PIPELINE PIPES FOR GAS MAINSSUBJECTED TO STRESS CORROSION CRACKING

摘要

The failures of gas pipelines and equipment are the results of general (uniform) and localrn(pitting) corrosion. However, the most aggressive corrosion attack is Stress Corrosion Cracking (SCC).rnProtective coating of long-distance gas pipelines cannot provide a 100% protection of external surfacernfrom SCC by the reasons as follows: production, transportation and constructional defects, coating agingrnand destruction during its exploitation. Cathodic protection enables protection of pipe metal againstrncorrosion attack related to general corrosion at a point of coating damage. However, this technology doesrnnot protect pipes from SCC. Among the ways of enhancing operational reliability of gas mains is the usernof pipes with enhanced resistance to SCC. The paper presents the results of tests of specimens cut fromrngas pipeline pipes manufactured at different pipe plants. VNIIGAZ has developed a procedure forrnestimating resistance of pipe metal to SCC. At close mechanical properties of pipe metal specimens haverndifferent resistance to SCC. There is no direct relationship between mechanical properties of pipe metalrnand its resistance to SCC. The tests have allowed to conclude that one of the possible way of enhancingrngas mains reliability is the use of pipes manufactured by a technology of controlled rolling withrnaccelerated cooling.