Monitoring of Corrosion Parameters Within the Annular Space of Cased Natural Gas Transmission Pipelines

A method to evaluate the corrosive environment of annular spaces within casings of natural gas transmission pipelines using commercially available, “off the shelf” equipment has been devised and implemented by Consolidated Edison Company of New York, Inc.  Three separate locations were selected for test monitoring of corrosion rates on steel carrier pipelines operating within these environments. The locations were monitored for 14-16 months and average corrosion rates were established for a variety of representative conditions.  Test results confirmed the initial hypothesis that cased pipeline segments exists in relatively benign environments as long as cathodic protection, coating systems and electrical isolation status between carrier and casing are maintained.  These results lend further credence to the position that cased segments are inherently safer than uncased segments due to the extra layer of protection from third party damage, which remains the most significant threat to pipeline integrity.