Mobil Hopes to Stem Flow of Pipeline’s Problems : Environment: Repeated oil spills embarrass the firm but also make a 92-mile replacement conduit easier to sell.
After crude oil gushed from a ruptured underground pipeline into Bull Creek in Granada Hills in April, 1986, Mobil Oil Corp. sought to assure pipeline regulators that it had things well in hand.
In a letter to the State Fire Marshal’s Office, Mobil blamed the leak, caused by corrosion, on an ineffective pipe coating the company no longer used. “This particular case was an isolated incident . . . and is not indicative of the entire pipeline system,” the company said.
But in the next few years, more corrosion leaks occurred in pipe protected by coatings that were supposed to be better. Most recently, on Jan. 31, 1,777 barrels, or 74,634 gallons, of tarry crude flowed from a broken pipe in Valencia, some of it befouling the Santa Clara River.
By then, Mobil, the country’s second-biggest oil company, had given up on the pipeline. It had poured millions of dollars into oil spill cleanup, a trend that seemed sure to continue as long as the badly corroded line remained in service. So when the Valencia spill occurred, Mobil was well along in planning a new $88-million, 92-mile pipeline to bring crude oil from Kern County to its Torrance refinery. The new line, according to Mobil, will feature a state-of-the-art coating and other safety improvements.
But at times in the past, Mobil was overly optimistic about the coatings it used to stem corrosion. And human error seems to have been a factor in some accidents. With Mobil poised to start construction, it remains to be seen if the new pipeline will avoid the problems that have made the existing line a dismal performer.
Since late 1985, the pipeline has suffered numerous leaks and ruptures--some of them small and some occurring during hydrostatic testing, when water is flushed through the pipe at abnormally high pressure to check for weak spots.
Counting only the seven leaks that exceeded a federal reporting threshold of 50 barrels, or 2,100 gallons, the risk of accidents during the five years from the end of 1985 to the start of 1991 was about 10 times higher than for the average crude oil line of similar age, according to data contained in the environmental impact report prepared for the new pipeline.
“The line’s a chronic leaker,” said Jim Wait, chief of the state fire marshal’s pipeline safety division, which regulates intrastate pipelines such as Mobil’s.
Many petroleum pipelines crisscross Los Angeles, but Mobil’s is unique for its “inordinate” number of spills, said Ken Cude, division engineer for the city Department of Transportation.
Mobil spokesman Jim Carbonetti acknowledged the pipeline’s problems, adding: “That’s why we want to replace it.”
Although the frequency of spills is an embarrassment to Mobil, it has made the new line easier to sell. For example, the state fire marshal and city Transportation Department have been unabashed supporters, citing the repeated failures of the existing line.
Although opponents of the project, banded together as the Coalition Against the Pipeline, have filed suit to block construction, the continuing threat of spills from the existing line has almost surely cost them allies.
Portions of the pipeline are 50 years old--a fact officials of Mobil and the State Fire Marshal’s Office are quick to mention. But other experts say age alone is no excuse--that a pipeline that is properly installed and maintained will last virtually forever.
“There’s something else that’s going on, no question about it, because age itself is not a problem with the pipelines,” said Richard Beam, deputy associate administrator of the federal Office of Pipeline Safety, a branch of the U.S. Department of Transportation.
“It’s a question of how the line was designed, constructed and what its maintenance record is,” Beam said.
In fact, three-fourths of the pipeline is 20 years old or less, and it is on these sections that most of the recent accidents have occurred.
January’s spill in Valencia, another spill in Valencia of 1,040 gallons in May, 1990, a 132,000-gallon spill in Encino in September, 1988, and a 105,000-gallon spill in Lebec in June, 1987, all occurred in pipe sections installed from 1971 to 1975.
External corrosion was blamed for each of those accidents. In each case, the protective coating on the outer wall of the pipe “disbonded”--or tore away--allowing moisture to corrode the steel.
Corrosion is an electrochemical process that results in thinning of metal. It can be thought of as nature at work, converting refined metal back to ore. It occurs when electric current flows away from the pipe, taking metal ions with it. Soil moisture serves as a conductor of the current.
Corrosion protection is a two-step process. First, pipe is coated in the factory with epoxy, coal tar or other materials to keep moisture away. Then, after the pipe is installed, a backup method known as cathodic protection is used to protect any pipe that may be exposed through holes in the coating. This involves running an electric current through the soil to the pipe to overcome the corrosion currents trying to leave the steel. Holes in the coating allow the protective current to reach the exposed steel.
After several of the pipeline failures, however, officials with Mobil and the Fire Marshal’s Office theorized that the coating failed in a way that kept the cathodic protection from working. It appeared that the torn coating had created an air space between the soil and the pipe through which the current couldn’t pass.
There are several reasons why a coating may disbond. It may be improperly applied in the factory, or damaged during installation if not carefully buried.
Or it may simply be the wrong coating for the job at hand. The coating must be able to withstand “soil stress”--the beating it takes as the pipeline moves in the ground in response to changing temperature or pressure. And on certain pipelines, like Mobil’s, it must be capable of surviving high temperatures. Mobil’s is a “hot” oil line, in which the tarry crude is heated up to 180 degrees to keep it flowing.
Over the years, Mobil experimented unsuccessfully with a variety of coatings. Writing in the industry publication Oil & Gas Journal in May, 1987, James A. Nunn, corrosion manager for Mobil’s pipeline subsidiary, told how Mobil had expected each coating it tried “to be superior to its predecessor.” But coatings that were “expected to perform well under high-temperature conditions,” Nunn wrote, “have failed to reach full expectations.”
The April, 1986, Granada Hills spill was a case in point. The ruptured pipe, installed in 1964, was covered with a coal tar coating that Mobil called T-1. T-1 had proven to be ineffective, and after the spill Mobil informed the Fire Marshal’s Office that it was in the final stages of replacing all remaining T-1 coated line.
In subsequent years, corrosion leaks struck sections of pipe protected by other coatings.
In some ways, the line’s problems parallel those of the Trans Alaska pipeline, the 800-mile artery that moves oil from Alaska’s North Slope to the tanker port of Valdez. Constructed in the mid-1970s by a consortium of oil companies, including Mobil, the pipeline was supposed to have decades of trouble-free operation. But recent tests have revealed significant corrosion, partly due to coating failures, that may cost $1 billion or more to repair.
Along with coating failures, careless mistakes may have been a factor in some of the Mobil accidents. For example, after the 132,000-gallon Encino spill in September, 1988, officials discovered that the ruptured pipe had been laid on top of a steel water line when installed in 1975. Experts say a steel pipe should never be placed against another metal line, as corrosion currents can be created between them. The city water line had been there long before the Mobil pipeline, but Mobil’s construction records did not mention it, according to a report in the Fire Marshal’s Office.
Human error also may have caused a 105,000-gallon spill in Lebec in June, 1987. The break occurred next to a section of pipe that had been repaired in 1983. Protective tape had been wrapped around the area of repairs. “It is believed that the primary cause of the corrosion was from improper tape application in 1983,” according to a memo in the state fire marshal’s files. This conclusion was Mobil’s, according to an official in the Fire Marshal’s Office who said he had no further details.
One important feature of the proposed new pipeline is its uniform 16-inch diameter. The uniform width will allow Mobil to use a sophisticated inspection device, known as a “smart pig,” that detects the thinning of pipeline walls so that repairs can be made before leaks occur.
The existing line varies between widths of 10, 12 and 16 inches. According to Mobil, it changes diameter 42 times. Using a pig to inspect changing widths is extremely expensive, industry officials say, because separate equipment is required each time the diameter changes. Only one 19-mile segment of the existing line that has uniform width is suitable for pigging, Mobil officials say.
However, most segments of the line were installed in the 1970s and 1980s, when use of pigs became widespread.
Carbonetti, the Mobil spokesman, said the company’s decision to use varying diameters “occurred before the full development” of smart pigs. Whether the use of varying widths was justified or “in error,” he said, the problem of pigging the line “is a good reason” to replace it.
Another much-touted improvement is a state-of-the-art coating developed for Mobil by Valspar Inc. and Du Pont Canada Inc. The coating is a blend of epoxy--which has superior bonding properties but is somewhat vulnerable to moisture--and polypropylene, which provides strong moisture protection but doesn’t bond as well.
“We do not know, it is true, that in 50 years you will not spring any leaks,” said Toni Pfaff, technical consultant to Valspar. But the hybrid coating is “the very best that the industry has been able to come up with,” he said.
“There is no guarantee, but the research has indicated it’s a better product,” agreed Cude, the division engineer with the Los Angeles transportation department.
Larry Teeter, attorney for the Coalition Against the Pipeline, said he does not share that confidence. “I don’t think we should be confident about it unless we see the evidence, and I don’t see the evidence,” he said.
Although still needing approval from several cities, Mobil has permission to build a 25-mile section through the Angeles National Forest and 26 miles of pipeline within the city of Los Angeles. The Los Angeles phase of the work could start this summer, as soon as the city approves a plan to manage traffic snarls from construction.
The coalition lawsuit, filed against the city of Los Angeles and Mobil, contends city approval should be voided because it was based on a faulty environmental impact report. Among other things, the suit says, the report did not adequately consider the risks of additional oil refining in a city that already has the nation’s dirtiest air.
The existing pipeline carries 63,500 barrels a day--just over half the crude processed at the Torrance refinery.
The new 16-inch diameter line could carry twice as much, leading opponents to charge that it is a foot in the door for more refining in the area.
But Mobil says it will not increase production in Torrance or pipe in oil for other refiners. Plans call for transporting 95,000 barrels of oil a day through the pipeline--1 1/2 times as much as now. But the company says it will simultaneously cut crude deliveries to the refinery by trucks and seagoing tankers.
Mobil also argues that the larger line won’t need as much heating to move the oil--which should extend the life of the coating.
Recent Accidents
The seven leaks that exceeded a federal reporting threshold of 50 barrels, or 2,100 gallons
Date Site Gallons Spilled Jan., 1991 Valencia 74,634 May, 1990 Valencia 1,040 Sept., 1988 Encino 132,000 June, 1987 Lebec 105,000 June, 1986 Torrance 6,300 April, 1986 Granada Hills 28,980 Nov., 1985 Van Nuys 2,520
Chart does not include leaks resulting from hydrostatic testing of pipeline.
