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News ReleaseMarch 22, 2002 Tiny Hole in Steel Pipe Led to 2001 Incident
Santa Fe: The combination of corrosion and increased pressure caused a tiny hole – smaller than a grain of rice – in a natural gas line and led to an explosion that leveled a building in Santa Fe last year, PNM officials said today. According to an internal PNM investigation,
PNM personnel failed to adequately assess the condition of
the eight-inch, carbon-steel pipe where the gas leak occurred
before increasing gas pressure during a standard process known
as "uprating." The internal investigation also concluded
the uprating process was flawed and should have been discontinued
because numerous leaks were discovered.
PNM’s conclusions are consistent with the findings of a report issued today by the state Pipeline Safety Bureau, a division of the Public Regulation Commission. The bureau combed through years of pipe inspection and maintenance records and conducted extensive interviews with PNM employees during its investigation. "In this particular instance, our personnel did not do the job we expect," said Melvin Christopher, PNM vice president of operations and engineering. "Decisions made in this instance were inconsistent with PNM policies and our commitment to safety. We have made important changes to address the problems that resulted in the explosion." The explosion occurred April 25, 2001, after natural gas seeped from a hole measuring one millimeter by 1.8 millimeters – or less than one-sixteenth of an inch – and migrated into the walls of an office building at 851 Cerrillos Road. About 2:30 p.m., an office employee stepping outside to smoke a cigarette inadvertently ignited the gas. The explosion leveled the building and trapped another employee in the rubble. The two office workers are recovering from their injuries. PNM did not receive any calls reporting the smell of natural gas in the area before the explosion. PNM’s most recent search for leaks in the area occurred just 10 days before the explosion as part of its uprating procedure, and no leak was detected. Since the incident, PNM has taken numerous steps to avoid a similar accident and improve its system to ensure safe operation, Christopher said. For example, immediately following the explosion, the company replaced more than 8,100 feet of pipe in that area – including the section where the hole was found – with polyethylene pipe that cannot corrode. The company also spent more than $4.7 million in 2001 to replace natural gas lines throughout New Mexico, he said. "Our extensive investigation leads us to conclude that this was an isolated incident," Christopher said. A firm that examined the pipe where the hole was found showed corrosion affecting the 70-year-old, uncoated pipe beneath Cerrillos Road was isolated to a small area and occurred under unique circumstances. CC Technologies, an international research and testing firm specializing in corrosion and corrosion control, evaluated a 12-foot section of the pipe and presented its findings to PNM and state officials earlier this month. "The hole was caused by a combination of corrosion and increased pressure. Both factors were dependent on each other," said Kevin Garrity of CC Technologies. The steel pipe, which had no internal corrosion, was buried about 43 inches below the Cerrillos Road pavement and about 14 inches from an underground water pipe. The hole faced the water pipe and scaling on the gas line suggested the water pipe might have had an intermittent leak, increasing the chances for corrosion, Garrity said. PNM’s Findings
PNM Actions
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