El Paso Proceeding with NM Pipe Integrity Testing

El Paso Natural Gas has received approval from the U.S. Department of 
Transportation's Office of Pipeline Safety (OPS) to conduct more internal 
inspections on its rebuilt New Mexico pipeline, which ruptured August 19 
killing 11 people (see Daily GPI, Aug. 22). Since the explosion, flows 
through the line, which runs from West Texas to California, have been reduced 
to 85% capacity, or about 920 MMcf/d. 

OPS said the El Paso line has already been repaired and put through 
hydrostatic testing, which it passed. Hydrostatic testing checks for cracks 
by forcing high-pressure water through the line. Now El Paso has the green 
light to begin smart pig testing, which will examine the internal integrity 
of the line. The device, called a pig because of the sound it makes during 
inspections, has sensors and once placed inside the line, it can detect 
dents, deformities and changes in wall thickness. 

Neither OPS nor El Paso released a timetable as to when the pigging would 
occur or how long it would take. However, once the testing is completed, the 
results will be evaluated by OPS, which then would determine if the line were 
safe for commercial use. 

OPS has not issued actual regulations on smart pig use, but they have become 
increasingly sophisticated and more widely used. Even though hydrostatic 
testing can actually detect certain flaws that are invisible to smart pigs, 
the pigging process is considered a complement to the water testing and 
ensures more integrity in test results. 

OPS requires all pipe to undergo at least one hydrostatic test after 
construction. Although not mandated, OPS also has proposed requiring 
pipelines that transport liquid petroleum products to use direct assessment 
methods such as pigging to evaluate the pipeline's integrity. Other types of 
inspections include using magnetic particles or ultrasound to measure the 
pipe wall's thickness. 


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