October 2016, Vol. 243, No. 10

Features

As Pennsylvania Pipelines Age, Role of Corrosion in Accidents Examined

Thirty years of watching metal fail, often spectacularly, and Mehrooz Zamanzadeh has developed some go-to mantras.

“Mother Nature doesn’t like what she didn’t make,” he likes to say.

That means when a man-made object is exposed to the environment – say, a metal pipeline is buried in soil – that environment will begin tugging and pulling, trying to break the metal into its natural parts, to undo the decades of technological advances at steel mills, in coating factories, in the field.

All that is another way of describing corrosion, one of the leading causes of pipeline leaks and failures, big and small. Corrosion was found on a weld that burst open in late April on a Texas Eastern pipeline in Westmoreland County’s Salem Township. The explosion left one man severely burned, destroyed his house, charred cars and melted a road.

In Pennsylvania, where half of the natural gas transmission pipeline miles are at least 45 years old, corrosion accounted for 28% of serious pipeline accidents over the past 30 years. The vast majority of those struck lines between 30 and 60 years old. That tends to be when corrosion barriers put on pipelines, such as coatings and cathodic protection, start to fail with greater frequency, Zamanzadeh, who everyone calls Dr. Zee, said.

As a corrosion specialist, Zamanzadeh studies the menace of age. He leads Robinson-based Exova, a lab stuffed with samples of exploded gas pipelines, leaky valves, airplane filters, transmission towers – any kind of metal that has lost its battle with nature. He’s not an alarmist but much of what he says sounds ominous.

Zamanzadeh said that just because a pipeline has performed without red flags for decades doesn’t mean something won’t go wrong tomorrow. In fact, the risk increases all the time as that pipeline ages, acquires wrinkles in its coating, and wiggles around underground under the pressure of outside impacts or the seasonal expanding and contracting of the earth.

It’s like his body, Zamanzadeh said. At 65, he’s healthy and agile enough to climb Mt. Everest, but there’s no doubt he’s not as sturdy as he was 30 years ago. And it would be naïve to think he won’t weaken further in another 30 years.

When the dust settles on serious pipeline accidents, like the one in Salem Township, the conversation often to aging infrastructure.The majority of pipelines in the U.S. today were put in the ground before 1970.

There’s some disagreement on how to assess the dangers of the aging pipelines.

“Not surprisingly, when an older pipeline fails, there is a tendency to suspect that age played a role in the failure,” reads a 2012 report commissioned by the Interstate Natural Gas Association of America Foundation, a Washington-based trade group that represents the pipeline industry. “This can lead to the perception that such pipelines are too old to operate safely.”

The trade group’s report disputes that. “A well-maintained and periodically assessed pipeline can safely transport natural gas indefinitely,” the organization’s study concluded.

Darius Kirkwood, a spokesman for the federal Pipeline and Hazardous Materials Safety Administration (PHMSA), which regulates gas pipelines in the U.S., said the agency can generally echo those conclusions.

Image courtesy of Pittsburgh Post-Gazette

“There is not necessarily a direct relationship between pipeline age and fitness for service,” he said. “You can’t automatically assume that an older pipe is less fit.”

A number of studies, however, including the pipeline administration’s data, show that failure events do increase with age. They follow what is known in engineering and risk assessment circles as the bathtub curve. A high number of initial failures gives way to a period of steady status quo which then starts to see more failures again as pipelines age.

It is theoretically possibly to monitor an old pipeline so closely and attend to its needs so carefully that it never fails – although Zamanzadeh noted that requires a healthy budget and people who know what they’re doing.

A large number of instruments and techniques – developed in part through lessons learned from accidents from the past – are now available to track pipeline health. Many are mandated by federal regulators. But in Zamanzadeh’s experience, many pipeline operators don’t know the extent of what they have in the ground, which is critical for designing an effective monitoring strategy.

It’s not uncommon for him to surprise his clients with a reading of materials he found in their failed samples.

“They don’t have any idea where did it come from, who was the supplier,” he said. “They don’t have the drawings.”

The Past is Present

Zamanzadeh’s office is cluttered with failed metal – a porous railroad tie (a manufacturing defect), a thick section of boiler pipe, bulged and ruptured at one end. Across from his desk is a natural gas transmission pipe nearly as tall as its owner, torn open by an explosion several years ago. It happened in Pennsylvania. Zamanzedeh couldn’t say any more about it.

“I think it’s a beautiful sculpture,” he said, “a case of great importance.”

His wife won’t let him display it in their home so the gashed, rusting pipeline takes up a significant chunk of real estate in his office.

“Fractures and failures are releases of energy and are fantastic,” he said.

The walls of Exova are lined with framed pictures of failures – extreme close-ups artistically rendered by his mother-in-law.

In general, he said, aging materials fail due to either corrosion or fatigue. Either they’re scoured by their environment or overworked. It often happens because pipeline owners don’t have the resources to fully assess the risk.

“Many of these gas companies and engineers, they try their best. But their hands are tied.”

An Eerily Similar Case

The boom in shale development over the past decade – in Western Pennsylvania and in other parts of the U.S. -has kickstarted a major buildout of new pipeline systems designed to avoid the mistakes of the past. These new lines aren’t substituting existing pipelines. They’re supplementing the older lines. And while better technology is added to the ground every day, aging pipelines also carry the burden of outdated design and construction practices.

The Salem Township explosion in April originated at a weld that was coated with tape, a method no longer used today. A preliminary study of the burst pipe found a defect in that coating and uncovered corrosion underneath it.

While a definitive cause is not yet known – Spectra Energy, which owns Texas Eastern, and federal regulators are still investigating – the finding prompted Spectra to start digging up and examining hundreds of other tape-coated welds along a 263- mile stretch of the pipeline across much of Pennsylvania.

Thirty-one years ago, almost to the day of the Salem Township explosion, a blast rocked a neighborhood in Beaumont, KY. The details were eerily similar. A loud bang and a woosh of air were reported. Nearby residents thought a plane had crashed. A huge fireball menaced the sky.

There were other common themes: both explosions involved pipelines 30 inches in diameter along the Texas Eastern system. Both were installed three decades before they burst. Each shared a right of way with other pipelines and was located about a mile from a compressor station.

But the Kentucky accident, which left five people dead and three injured, had something the Pennsylvania accident did not: its gas pipelines were encased in another 36-inch pipe. That was a practice pushed by the railroad industry under its crossings and picked up by municipal officials who thought it added another level of protection in case of a leak or rupture.

Instead, it created the conditions for corrosion and shielded the gas pipeline from meaningful detection.

“It’s a huge, huge, huge problem for anybody that has pipelines from the 1940s up to the 1980s,” said David Wint, director of pipeline integrity engineering at Audubon Field Solutions in Oklahoma.

The exploded pipe in Salem Township was installed in 1981 and did not have a casing around it under the intersection of Route 22 and Route 819. But such conditions still exist from older pipelines.

In May 2014, a Spectra Energy welder was repairing a casing surrounding 30-inch pipeline on the Texas Eastern system in Greene County when he accidentally dinged the gas pipe and caused a leak. That piece of pipe was installed in the 1950s.

When Problems Spike Again

Corrosion and fatigue aren’t unique to pipelines. They’re ubiquitous in infrastructure: bridges, roads, water towers.

With 300,000 miles of natural gas transmission pipelines in the U.S., the network is the safest method of transportation. Last year, more than 38,000 people were killed in vehicle crashes. Deaths from any kind of pipeline totaled 347 for the past 20 years.

Pennsylvania has had about two serious incidents a year over the past two decades on natural gas transmission pipelines. Much of the existing infrastructure is at a point where problems creep up with greater regularity. It’s also when corrosion-related failures are most prevalent.

Overall, the most common cause of failure in federal and state-level data is material, weld, or equipment failure – such as when a weld defect fails under pressure, for example. Those tend to peak in the first few years of a pipeline’s life, then level off and return to prominence after 50 or 60 years in operation.

At a National Association of Corrosion Engineers (NACE) conference in Houston, two Ohio-based engineers presented data based on five years of failure investigations performed by DNV GL, a Norwegian testing, certification, and advisory firm that’s often a company’s first call after a rupture. DNV GL is testing the pipe involved in the Salem Township explosion.

The company’s analysis mirrored federal statistics. It showed that about 15% of failures hit pipelines in the first few years of operation. Then, after leveling off for the next four decades, accidents picked up again after 50 years of service life.

More than half of the failures in DNV GL’s analysis were caused by material, weld, or equipment failures, and a third was because of corrosion.

Studying the causes of pipeline failures has spurred an industry of new risk assessment tools and methods.

In Zamanzedeh’s laboratory – where metal is sliced and diced every which way, misted with salt water and probed by $800,000 microscopes – his favorite motto is an uplifting one.

Failure, he said, is a discouraging word. But failure analysis – “the two most beautiful words in the English language.”