Cathodic protection problem for a gas pipeline near a compressor station

"Cathodic protection problem for a gas pipeline near a compressor station"

A. Aghajani

Materials Performance, January 2017, VOL. 56, NO. 1, page 2-4

Abbstract :

A 56-in.-diameter gas pipeline was monitored using a magnetic flux leakage pig. Significant local corrosion close to a compressor station was diagnosed before the gas pipeline experienced a failure. A field study showed that cathodic protection (CP) potentials in the corroded area failed to satisfy established criteria for protection due to concentration cells and CP interference. Replacing the gas pipeline with a new coated pipeline resulted to effective CP potentials through adding local CP. The results suggest that local variations in soil resistivity can affect the CP potentials of a pipeline and sometimes cause local underprotection. Therefore, the type of soil layers located around and under the pipeline must be considered in CP design. Also, segmenting a pipeline that traverse soils with varying conditions offers the option of providing effective corrosion control with separate CP systems.