PUBLIC SERVICE CO OF COLORADO
gas_transmission Incident — — June 29, 2010
Incident Information
| Incident Date | June 29, 2010 |
| Operator | PUBLIC SERVICE CO OF COLORADO |
| Commodity | NATURAL GAS |
| Pipeline Type | gas_transmission |
Location
| State | |
| Coordinates | 39.55286, -106.39094 |
Cause
| Cause | MATERIAL FAILURE OF PIPE OR WELD |
| Subcause | ENVIRONMENTAL CRACKING-RELATED |
Casualties
| Fatalities | 0 |
| Injuries | 0 |
Costs
| Property Damage | $3,500 |
| Emergency Response | $6,500 |
| Other Costs | $0 |
Location Map
Incident Narrative
AN AERIAL LEAK SURVEY WAS BEING CONDUCTED ON JUNE 29, 2010. A LEAK WAS DETECTED IN A REMOTE AREA OF THE WHITE RIVER NATIONAL FOREST SOUTH OF MINTURN COLORADO. CREWS WERE DISPATCHED AND ISOLATED THE SUBJECT SECTION OF THE 4 INCH TRANSMISSION PIPELINE. THE FAILURE WAS ATTRIBUTABLE TO STRESS-CORROSION CRACKING (SCC). A COLONY OF SCC DEVELOPED ON THE EXTERNAL PIPE SURFACE BENEATH A LAP IN THE TAPE WRAP COATING THAT HAD DISBONDED. THE INTACT BUT DISBONDED COATING ALLOWED MOISTURE TO COME IN CONTACT WITH THE PIPE SURFACE AND THE HIGH DIELECTRIC STRENGTH OF THE TAPE COATING EFFECTIVELY SHIELDED THAT AREA OF THE PIPE SURFACE FROM CATHODIC PROTECTION. INDIVIDUAL SCC GREW IN LENGTH AND DEPTH COALESCED TO FORM ONE LARGE CRACK THAT EXCEEDED THE RESISTANCE OF THE MATERIAL AND CAUSED THE FAILURE. THE FACT THAT THE SCC WAS CIRCUMFERENTIALLY-ORIENTED INDICATES THAT THE PRIMARY LOAD ON THE PIPELINE WAS AXIAL TENSION RATHER THAN HOOP STRESS. THE SOURCE OF THE BENDING STRESS WAS BELIEVED TO BE SOIL SETTLEMENT IN THE RIGHT OF WAY.
About This Pipeline Incident
Pipeline incident data is reported to the Pipeline and Hazardous Materials Safety Administration (PHMSA). All significant incidents involving fatalities, injuries, or property damage over $50,000 must be reported.