What is a BLAST RADIUS?
The blast radius is the distance that the fire from the explosion consumes, measured in feet from the epicenter to the outer edge of the burned area. Many factors can increase the estimated blast radius such as residential homes, forests, other gas lines, utilities, businesses and industrial facilities.
The map below shows the proposed pipeline route through Medina County and the possible scenarios in the event of a pipeline explosion pending the pressure at which the pipeline is operating.
- The pipeline route is represented by the dark red line in the middle of the shaded area.
- The light red shaded area represents a blast radius while operating at a higher pressure capacity (1440 psi).
- The very outer light orange shaded area represents a 2 mile radius evacuation zone.
NOTE: Map Layer control (icon in upper left corner of map) allows you to turn the above zones on and off.
These distance estimates were made after
- consulting the report “A Model for sizing High Consequence Areas” by C-Fer Technologies done on behalf of the Gas Research Institute in October 2000. Read the Full Report: A Model for sizing High Consequence Areas
- consulting C. Rhodes, P. Eng., Ph.D. of Xylene Power LTD. Xylene website: NATURAL GAS PIPELINE SAFETY SETBACK. CALCULATION OF SAFETY SETBACKS FROM LARGE DIAMETER HIGH PRESSURE NATURAL GAS PIPELINES
View Nexus Pipeline Blast Radius in a larger map
Important Quotes
From the report titled “A Model for sizing High Consequence Areas” (HCA) is described as follows.
“The definition of High Consequence Areas is expected to require additional protection for people with limited mobility such as day care centers, old age homes, and prisons. This report suggests the definition for the HCA area of increased protection be set by two parameters, the pipe diameter and it’s operating pressure.”
Furthermore, the report acknowledges that natural gas pipelines do “rupture” and carry “a significant threat.”
“The rupture of a high-pressure natural gas pipeline can lead to outcomes that can pose a significant threat to people and property in the immediate vicinity of the failure location. The dominant hazard is thermal radiation from a sustained fire and an estimate of the ground area affected by a credible worst-case event can be obtained from a model that characterizes the heat intensity associated with rupture failure of the pipe where the escaping gas is assumed to feed a fire that ignites very soon after line failure.”
How Big of a Blast Radius Are We Talking About?
PIPELINE PRESSURES
The Nexus pipeline diameter is estimated to be 42″ and approximately 250 miles long. Typical operating pressures for this size transmission line can range between lower pressures around 800 PSI (pounds per square inch) to higher pressures of 1500 PSI.
Calculated Hazard area radius (blast zone) chart based on pipeline diameter and operating pressure.
CALCULATED HAZARDS AND REAL WORLD STATISTICS
The data on actual pipeline failure incidents tells a slightly different story as many actual incidents report a greater radius of burn than does the actual graph established by this report.
For instance, a blast near Bealeton, Virginia (1975 NTSB-PAR-75-2) burned a radius of 700 feet at less than 800 PSI when the chart above shows burn radius should have been no more than approximately 525 feet.
Thus the actual burn radius was 75% greater than hypothesized.
Another incident involving a 30″ pipe was near Jackson, Louisiana (1984 NTSB-PAR-86-1) burned an area 1450 feet long by 360 feet wide (furthest fire extent 950 feet) while operating at 1016 PSI which claimed 5 lives within 65 feet (0 foot offset) and 23 injuries within 800 feet (180 foot offset).
The actual burn radius for this incident is 45.52% greater than the 660 foot burn radius hypothesized.
