A gas transmission line blast in New Jersey last March has prompted the National Transportation Safety Board to recommend an added safety measure.
NTSB said high pressure pipelines should be retrofitted with automatic or remotely operated main line cutoff valves in urban areas to help reduce line leaks and prevent explosions.
The agency found that a Texas Eastern Transmission Corp. gas pipeline rupture in Edison Township New Jersey, Mar. 23, 1994, was caused by third party damage.
NTSB's report said, "Line 20 was gouged by excavation equipment, such as a backhoe, at an undetermined time after the pipeline was internally inspected in 1986. The mechanically induced gouge likely created a crack that grew to critical size, most likely as a result of metal fatigue."
The accident occurred on the property of Quality Materials Inc., an asphalt plant. The force of the rupture and natural gas escaping at a pressure of about 970 psig blew pipe fragments, rocks, and debris more than 800 ft.
The escaping gas was ignited in a minute or two, setting roofs on fire in a nearby apartment complex and destroying eight buildings. About 1,500 persons were evacuated, and about 103 received minor injuries. A woman living a mile away suffered a fatal heart attack.
NTSB pegged damage from the accident at more than $25 million.
BEFORE THE ACCIDENT
NTSB said Quality Materials failed to tell its employees about the pipeline on plant property and its potential hazards and took no precautionary measures to protect Line 20 from excavation damage by employees.
NTSB said, "Although many of Texas Eastern's requirements and procedures surpassed those required by federal regulations, the company's (aerial) surveillance procedures did not stress that employees identify excavation activities within industrial locations that could endanger its pipeline.
"Texas Eastern's lack of automatic or remotely operated valves on Line 20 prevented the company from promptly stopping the flow of gas to the failed pipeline segment, which exacerbated damage to nearby property."
The report complained that the Transportation Department's Research and Special Programs Administration (RSPA) "has repeatedly failed to address public pipeline safety concerns" in a timely manner.
NTSB urged RSPA to expedite requirements for installing automatic or remotely operated main line valves on high pressure pipelines in urban and environmentally sensitive areas and develop toughness standards for new pipe installed in urban areas.
It said RSPA should set standards for permanent markings that identify the location of high pressure gas and hazardous liquid pipelines in urban, industrial, and commercial areas, and speed a study on how to lower risks associated with the siting of pipelines.
NTSB urged the Interstate Natural Gas Association of America, Association of Oil Pipelines, American Petroleum Institute, and American Gas Association to encourage their members to inform the public about precautions that should be taken near high pressure pipelines.
It also recommended that the organization encourage their members to modify valves in urban or environmentally sensitive areas for remote or automatic operation. The aim is to reduce the time required to stop the flow of natural gas or hazardous liquids to failed pipeline segments.
PIPELINE'S REACTION
A Texas Eastern spokesman responded, "We're pleased that NTSB determined that many of our operations do exceed federal standards.
"We need more time to review the report, but on balance it appears to be a fair assessment of the accident."
Ingaa said NTSB previously recommended shutoff valves for gas trunk lines in urban areas and for oil lines in environmentally sensitive areas. RSPA has a rulemaking under way on the latter issue.
Ingaa also said the Gas Research Institute is studying ways to improve gas line shutoff valves.
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