More than 2.2-million mi. of natural gas and liquid petroleum pipeline serves as an essential, yet potentially lethal lifeline for U.S. energy needs. This matrix of pipe delivers more than 20 trillion cu. ft. of natural gas and 13 billion barrels of petroleum products per year.
However, as these pipeline systems age, the likelihood for catastrophe grows, and federal regulations, as well as their enforcement, remain undeveloped.
This dilemma roared into our nation’s consciousness on Aug. 19, 2000, when a ruptured natural gas pipeline ignited near a campground along the Pecos River, about 20 mi. south of Carlsbad in southern New Mexico.
At approximately 5:26 a.m., the sky lit up with a 500-ft. pinnacle of fire witnessed all the way to Carlsbad. A fireball of burning gas and searing heat swept down the riverbank, engulfing campers 600 ft. away.
Investigators found three charred pickup trucks — their tires liquified — and the outlines of what were tents melted over the ground. The initial explosion was so intense that, according to a federal official, it turned sand into glass and portions of a nearby concrete bridge to powder. The accident eventually claimed the lives of all 12 campers, including five preschool children.
The 30-in. (76.2 cm) El Paso Natural Gas Co. pipeline was one of three parallel lines running 5 ft. (1.5 m) underground and carrying fuel from West Texas to California and points in between. Automated pressure gauges immediately alerted gas company employees to a massive drop in pressure when the conduit ruptured, but it took nearly an hour after ignition before they could shut off the flow of gas.
“It was a very remote area, and it could have been just about anything that ignited the gas,” said Kim Wallace, spokesperson, El Paso Natural Gas. They have not determined the ignition source.
“We have metering instruments located at several places along the line, and we had to determine between which two valves the rupture had occurred,” said Wallace. “These are manual valves and we had to actually send someone out to shut them off. We got them turned off just as quickly as we possibly could.”
The aftermath of the disaster left a crater 85 ft. long, 45 ft. wide and 20 ft. deep (30 by 13.7 by 6 m). Internal corrosion was discovered in the remnants of the fractured pipe.
“At this time, our investigation is still ongoing,” Keith Holloway, public affairs officer for the National Transportation Safety Board NTSB) said in mid-January. “We’re still in the fact-gathering stage. After that, we will go into our analysis which will determine the cause of the rupture. It can be a year or more from the time of the accident,” added Holloway.
Some residue and corrosion was found inside the pipe. However, it is known that there was corrosion found, but it is unknown whether the residue caused the corrosion.
“The residue can be caused by the quality of the gas, or just the way the gas settles in the pipe,” said Holloway. Some of the agents within the residue of the gas could cause corrosion. If there are any federal pipeline safety regulation violations, the Office of Pipeline Safety will handle that.”
The U.S. DOT’s Office of Pipeline Safety (OPS) issued a Corrective Action Order to El Paso Natural Gas within days of the accident, closing all three pipelines until a myriad of conditions were met, including hydrostatic testing, direct assessment of the integrity of the pipelines by both x-ray and ultrasonic examinations and a plan to re-open the lines under reduced pressure after repair and replacement of damaged areas.
Wallace said that Houston-based El Paso, the nation’s fifth largest natural gas pipeline operator with nearly 10,000 mi. (16,098 km) of conduit, has submitted its repair plan to the OPS and it has been approved.
“They’ve given us permission to begin making repairs in order to make that section of line piggable,” Wallace said. “When the pigging actually occurs, we’ll send the smart pig results to the OPS for their review. Following that, the OPS will let us know when we can put the pipe back in service and at what pressures.”
The two main methods of testing for corrosion, weld-breaks and other metal deformations are pigging and hydrostatic testing.
A “smart pig” is an internal testing device that travels through the pipeline and collects and stores data as often as every tenth of an inch. It can pinpoint the location of a defect within the pipe as close as 3.3 ft. (1 m). There are many types available, and pipeline operators have to first choose between degrees of detection and discrimination. There are two basic families of pigs — magnetic and ultrasonic.
Magnetic Flux Leakage (MFL) is one of the oldest pigging systems, dating to the 1960s. The magnetic flux field is deflected by any cracking or metal loss and the deflection is recorded by a sensor.
MFL tools can range from 7.5 to 18.4 ft. (2.3 to 5.6 m) in length and travel from 1.6 to 16.4 fps (0.5 to 5 mps). The MFL checks the circumference and can detect a decrease in wall thickness as small as 10 percent. Axial MFL tools come in varying resolutions and are very good at detecting long, narrow axial cracks, long corrosion and metal loss.
Ultrasonic tools also measure wall thickness by sending out compression ultrasonic waves. It is a much more precise corrosion mapping tool and identifies laminations and dents as well. The unit travels at 3.3 fps (1 mps) and cannot detect a crack less than .78 in. (2 cm) in size.
The ultrasonic shear wave is precise at detecting cracks from both corrosion and fatigue, but must go through a clean line. It requires a liquid medium and must be modified with a wheel probe and contained glycol to use it in gas lines.
A new tool in development for gas lines is the electromagnetic acoustic transducer. It has the same accuracy as the ultrasonic shear wave but uses a magnet to generate an ultrasonic sound through the pipe wall.
The hydrostatic test pressures the pipe with water to 1.25 times the maximum operating pressure. The theory is that this pressure will either cause serious defects to fail or prove that they don’t exist.
Many U.S. pipelines are 30 to 50 years old. In the last 10 years, there were 2,241 major pipeline accidents. Those incidents killed 226 people, caused $700 million of property and environmental damage and the rate of accidents is increasing at 4 percent a year. Over the same period, the number of fines imposed by the OPS decreased from 49 percent of all enforcement actions to just 4 percent.
A report by the General Accounting Office (GAO) reveals that OPS has failed to adopt 22 of the 49 safety requirements ordered by Congress since 1988. Some of these requirements are now five to 11 years past their implementation deadlines.
“OPS has not implemented some of the recommendations and requirements because it believes they would be too costly for the pipeline industry compared to expected benefits,” according to the report.
However, the NTSB remarked that some of OPS’s analysis of costs and benefits are flawed because the agency did not consider all the benefits. The agency has increasingly relied on letters of concern, instead of fines, to enforce its regulations, saying this approach allows problems to be fixed faster. OPS has not yet assessed the effectiveness of the new approach.
“The focus of our nation’s pipeline safety program and its regulator should be on preventing loss of life rather than on preventing the loss of a profit margin to industry,” said the GAO report. “Unfortunately, OPS seems to lack this focus and, consequently, the ability to regulate.”
The OPS conducted a system integrity inspection of El Paso Natural Gas Co. pipelines in May 2000, and “didn’t find anything,” said spokesperson Debbie Hinz. The OPS, however, has been funded for only 55 inspectors to cover the 2 million-plus miles of pipeline.
“It is a huge job,” said Hinz. “Of course we do have state programs where the states work with us to assist us in the inspections of intrastate pipelines. For the number of pipelines, we’re a very small organization with a very small budget. With more money, with more people, we could obviously do more. However, we take this very seriously. We work hard. We do what we can do with what we have. We have been trying to push for more funding.”
In that regard, the Carlsbad pipeline explosion may hold a silver lining. Motivated by that tragedy, the U.S. Senate in September unanimously approved legislation which would increase the OPS’s funding by $13 million per year, tighten regulatory and testing requirements for pipeline operators and dramatically raise penalties for violations.
Senator John McCain (R-AZ) co-wrote the bill with Washington Senator Patty Murray (D-WA). “Under this bill, pipelines will be inspected, operators will be qualified, whistleblowers will be protected and violators will be penalized,” said Murray. “This bill doesn’t just raise pipeline safety standards. It gives us the tools, the enforcement and funding to ensure that pipeline companies reach those standards.”
Although the majority of pipeline breaches are caused by damage from outside forces, the section of Carlsbad pipeline that ruptured had never been internally tested. The bends and valves in that section near the river crossing make pigging impossible. The pipeline was built in 1950, but it wasn’t until 1987 that federal regulations required a pre-service hydrostatic test for all new pipelines. Older pipelines were grandfathered in.
The pipeline operator has many choices with which to access the integrity of his pipe, all with benefits and limitations. New alternatives are needed, especially for areas of pipeline like the Carlsbad river crossing that contain obstructions and are not piggable, if we are to keep our energy lifeline from turning on us.
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