9 Internal corrosion The chemical composition of materials flowing inside the pipeline is another contributing factor.. Typically, a mile of pipe can be pulled through an existing pipel
Trang 1New Solutions for
Aging Pipelines
bakerhughes.com
Trang 2Pipelines run through rural and urban areas They run near schools, residential areas, and environmentally sensitive zones, including water supplies And they are aging at an alarming rate.
That amounts to nearly nine million gallons—one spill every two days. 1 A single incident in 2010, in which 840,000 gallons of tar sands crude oil spilled into Michigan’s Kalamazoo River, was estimated to cost $800 million for cleanup, earning it the dubious distinction as the most expensive pipeline spill in US history. 2
And these are just the ones we hear about An even larger but less publicized pipeline rupture occurred in Denver City, Texas in January of 2008 Over the course
of just 24 hours, a pipeline operated by a major operator spilled 1.3 million gallons of crude oil.
According to data from the U.S Department of Transportation, Pipeline & Hazardous Materials Safety Administration (PHMSA), Texas poses a particular problem The state has by far more miles of pipeline than any other In 2011, the state also had more significant leaks of hazardous liquids, which included crude, than in any year since 2002.3 (A significant leak is defined as an amount in excess of 2,100 gallons.)
With most pipeline infrastructure lying beneath the ground, it’s tempting for the industry to ignore the problem until a spill occurs But make no mistake—we are standing in a minefield.
Since 2010, there have
been 1,300 oil spills from US pipelines.
Trang 3Out of sight, out of time
There are 2.5 million miles of pipelines in the United States. 4 They carry all
of our nation’s natural gas and a majority of its oil and refined petroleum products, along with a variety of hazardous liquids that include LNG, anhydrous ammonia, and carbon dioxide They are found onshore and offshore, transporting commodities between producers, refiners, processors, terminals, distributors, and end users Literally, they are the lifeblood of industry, critical to the United States’ economic well-being
Generally speaking, there are three major types of pipelines: gathering
lines, which take unprocessed oils from wells to storage tanks; feeder lines, which carry oil from storage tanks
to transmission lines; and transmission lines, which take oil from these producing areas to refineries or various other end users
Pipelines run through rural and urban areas They run near schools, residential areas, and environmentally sensitive zones, including water supplies And they are aging at an alarming rate
According to the U.S Department of the Interior, more than half of these pipelines are at least 50 years old, many built
to accommodate the booming post-war demand for energy More than 12 percent of the nation’s cross-country gas transmission and hazardous-liquid pipelines were built earlier than 1950 Some even predate World War II. 5
Inevitably, these aging pipelines are prone to rupture—and age isn’t the only factor involved Leaks can result from material or weld failures, equipment failures, excavation damage, even natural disasters such as hurricanes However, the leading cause of releases on gas transmission and hazardous liquid pipelines is corrosion, which is directly affected by how long these lines have been in the ground In a study conducted from 2008-2016, corrosion was a factor in 24 percent of significant incidents. 6
The nature and causes of corrosion
Corrosion as a factor in pipeline failure takes into consideration several variables It can occur inside or outside the pipe In addition
to age, corrosion can be influenced by pipe composition, diameter, chemical makeup, flow velocity, and temperature of the materials being transported
Pipeline design has evolved over time Notably, some standards have proven to be more effective than others Just because one pipeline
is newer doesn’t necessarily mean it’s safer For example, cathodic-protection systems implemented in the late 1940s helped to mitigate oxidation damage from external corrosion On the other hand, some protection methods had good intentions that failed upon execution
In 2008, after a major
spill in Prudhoe Bay,
Alaska, one operator
discovered portions of
pipeline that had lost
more than 70 percent
of its mass to corrosion.
The Colonial Pipeline leak, which occurred
in March of last year near Birmingham, Alabama, spilled at least 250,000 gallons of gasoline It resulted in shortages and a price spike throughout the Southeast
And it occurred on
a 53-year-old section
of pipe.
Some early anti-corrosion pipe coatings have been show to be worse than having no coatings at all 7
A May 2015 crude oil spill that fouled California’s Santa Barbara coastline was due to a corroded section of pipe that was only 28 years old. 8 While maintenance, testing, and inspection practices have evolved, they vary from one operator the next, adding yet another variable to the mix
Pipeline composition
Some of the older pipelines are made of cast iron, which is extremely corrosion-resistant but offers low beam strength, making it vulnerable
to stress due to freezing, erosion, excavation, and other underground disturbances Smaller-diameter cast-iron pipes have even lower beam strength. 9
Internal corrosion
The chemical composition of materials flowing inside the pipeline is another contributing factor Carbon dioxide (CO2), hydrogen sulfide (H2S), and free water 10 along with a corrosive soup of microorganisms can cause major damage To increase the output of a well, operators will often inject CO2 or seawater into a formation These corrosives, along with the high temperatures characteristic of extracted crude, dramatically exacerbate the problem
Once these contaminants begin to collect in a pipeline, they eat away
at the interior steel surface This in turn attracts other particles, creating additional fluid turbulence and accelerating the process of corrosion In
2008, after a major spill in Prudhoe Bay, Alaska, one operator discovered portions of pipeline that had lost more than 70 percent of its mass to corrosion. 11
In terms of corrosive properties, not all crude is created equal The 875-mile Keystone XL Pipeline will transport a diluted bitumen referred
to as “dilbit,” which was the contaminant involved in the Kalamazoo spill Heavier and far more corrosive than conventional oil, many are convinced it may increase the likelihood of leaks. 12
What do we do? How do we start?
Regardless of the causes, the older these pipelines get, the more problems we’re going to see The Colonial Pipeline leak, which occurred
in March of last year near Birmingham, Alabama, spilled at least 250,000 gallons of gasoline It resulted in shortages and a price spike throughout the Southeast And it occurred on a 53-year-old section of pipe. 13
The industry and public generally agree that something must be done about the problem Formulating and implementing a solution gets a little more complicated, beginning with how do we determine what gets fixed first, and who fixes it
Trang 4Typically, a mile of pipe
can be pulled through
an existing pipeline in
as little as four hours.
Logistic challenges to replacement strategies
It’s tempting to say that the easiest solution is to simply identify problematic pipelines—the oldest or those in need of the most repair—dig them up and replace them This, however, is an expensive proposition
According to a 2015 report by the Department of Energy, replacing all
of the nation’s oldest and most vulnerable pipelines would cost $270 billion. 14 Given the current political and economic climate, such an appropriation is not likely to happen
There’s also the issue of managing supply disruption and planning alternate routes Replacing pipelines in urban areas would require tearing
up roads and removing existing utility lines for telephone, electricity, water, or cable services Municipal permitting, which is extremely time-consuming, is required Many pipelines are owned by corporations or public utilities, throwing another wrench into the works Because these entities may lack the authority to pass such significant expenses on to customers, they may be reluctant to take action. 15
The rehabilitation argument
On the whole, government is leaning on industry to address the problem
of pipeline infrastructure Aside from replacement, there are several viable options available on the market today for pipeline repair and/or rehabilitation
Welded patches, wraps, and sleeves are a conventional approach in which circular or square steel patches are welded to the outer diameter
of the damaged section of pipe This solution is preferable in situations where the damaged section can be isolated Steel clamps, which can be either bolted or welded to the outside surface, can also be used. 16
Welded solutions have their limitations, however While suitable for straight sections of pipe, repair around joints and bends is problematic
It’s also an expensive and cumbersome job, requiring excavation if the pipe is located underground Welding also increases the risk of explosion;
ASME B31.4 limits patch length to 6” and pipe diameter to 12” or less for welding on hazardous-liquid pipelines. 17
Thinking beyond steel
Composite wraps, in which a resin-impregnated fiberglass is wrapped several times around the leak, eliminates the risk of explosions because
no welding or cutting is required In an industry comparison, composite repair systems were an average of 73 percent less expensive than replacing the damaged section of pipe and 24 percent less expensive than welded steel-sleeve repairs. 18 While the process is relatively fast, the long-term effectiveness of this solution is still under evaluation
All of the above in-situ repair solutions involve excavation of the damaged section, which ideally is isolated to a small section of pipe
Therein lies the fundamental shortcoming of the patchwork approach:
addressing one leak is no guarantee you won’t have to soon contend with another, particularly if you’re repairing a 60-year-old section of pipe
A more flexible route
One promising alternative that addresses these limitations is a trenchless repair technique in which flexible, composite pipe is pulled through a section of damaged pipeline with a rope or cable Composite piping is lightweight and spoolable, making it easy and cost-effective to transport
Installation requires no heavy machinery or welding, and can be routinely performed in crowded oilfields with complex right-of-ways
The process itself is fast A pig is sent through the existing pipeline to inspect the bore, identify potential obstacles, and
provide an analysis of the pull force required After access points are excavated, a rope or cable is sent through the pipe with a pig and attached to the composite pipe, which is then pulled back through
Typically, a mile of pipe can be pulled through an existing pipeline in as little as four hours
This offers significant cost savings in both manpower, time, and material over conventional pipeline replacement—estimates are as low as
$16-$20 per mile for composite versus $46-$54 for steel
on average installation
Reinforced Thermoplastic Pipe (RTP)
For decades, RTP has successfully been used for oil and gas applications Typically, it features Polyethylene (PE), Polyamide-11, or PVDF reinforced
by various high-strength synthetic fibers or other material Compared to steel, RTP offers up to four times the corrosion resistance and eliminates—obviously—the need for chemical washes, rust inhibitors, anodes, cathodes, or DOT-regulated inspections
Spoolable and lightweight, RTP comes with significantly lower installation costs Low-friction characteristics also give it a higher flow rate than steel, which means smaller diameters can be used for the same project requirements Depending on the composite materials, there may be limitations when it comes to higher pressures and higher temperatures
Older generation composite pipe has been known to develop stress cracks under extreme environmental and operating conditions Poor fusion jointing can also cause problems. 19
Trang 5The entire rehabilitation project took about five hours, providing a much lower installation cost and a lower life-cycle cost.
New Steel Pipeline Vs RtP Rehabilitation
RtP* StEEL
Corrosion
Resistance internal fluids including Highly resistant to
crude oil, brine, chemicals, and bacteria
Corrosion inevitable over time; chemical-treatment program with exterior corrosion (cathodic) protection required Erosion
Resistance 8 – 12 times more erosion resistance
than steel
Lower erosion resistance
Permeation Ultralow permeation to
H2S, CO2, CH4, water vapor corrosion from Susceptible to
CO2 and H2S Flexibility Highly flexible, with a
3.92-ft min bend radius on 2.375-in pipe
No flexibility
Pressure
Capability Up to 2,000 psi requiring greater Up to 16,000 psi,
wall thickness Temperature
Capability Up to 180°F requiring greater Up to 700°F;
wall thickness
Weight Lighter-weight spools
reduce transport costs and simplify logistics; 6-in RTP is approximately 4 lbs./ft
6-in steel pipeline can be over 60 lbs./ft
Flow
Resistance diameters provide Low Smaller
greater flow rates
Greater resistance
Requires larger diameters, exacerbates erosion Deployment
and
Installation
Pull-through technique requires no trenching, heavy machinery, welding, permitting, or DOT inspections
Excavations at access points or sharp turns only
1 day per mile
New pipeline installation
is labor-intensive, requiring full excavation and trenching, welding, extensive permitting, and inspections
8 days per mile
Cap Ex Costs Rehabilitation:
$16 – 20K per mile for materials and installation
New steel: $46 – 54K per mile for materials and installation
Op Ex Costs Lower life-cycle cost —
no corrosion inhibitors
or pigging required, no paraffin build-up in bore
Requires ongoing chemical treatment programs and pigging, along with exterior corrosion (cathodic) protection
* Specified RTP product features a Thermoflex ® PPS base with a nylon PA12
inner sleeve, reinforced by Aramid fibers.
Composite options for strength
Composite layers, which vary by manufacturer, have been introduced to address these limitations To increase the strength and pressure capabilities, some products include a glass fiber-reinforced layer or epoxy laminate
However, many of these fiberglass solutions have problems with cyclical loading and stress fatigue They also have a tendency to weaken in the presence of fluids
Some composite products even feature a layer of steel
or steel mesh Of course, adding a layer of steel means adding weight Steel-reinforced composite solutions can
be as much as six-times heavier than other composites
And even some of the most popular steel composites cannot be used for H2S or CO2 applications, as these materials can diffuse into the annulus, resulting in accelerated corrosion
More effective and lighter methods of reinforcement include braided polyester or Kevlar® aramid fibers, both
of which can accommodate cyclical loading and surge pressures While polyester may exhibit problems with creep, aramid does not, giving it the advantage
While HDPE as a base layer offers greater corrosion, chemical and bacterial protection than steel, in some cases it requires the venting of fittings to allow gas release due to the permeation through the base HDPE core HDPE is also sensitive to bruising
Advanced alternatives for corrosion resistance
In addition to strength, corrosion resistance must be considered in evaluating an RTP solution As a base layer, Polyphenylene sulfide (PPS) offers 2-3 times the corrosion resistance of high-density polyethylene,
which is used in some low-pressure hydrocarbon applications PPS is also much more resistant to permeation, lasting up to 20-times longer than standard HDPE-lined products with no softening or swelling Nylon liners can also be introduced, offering additional protection against hydrocarbon contamination and paraffin
By choosing the right materials, an operator can optimize
a pipeline solution according to its application For example, a PPS pipe reinforced with an aramid layer would combine greater corrosion protection with greater strength, temperature, and pressure capabilities—up to 3,000 psi
New steel versus rehab:
a no-contest case study
In West Texas, numerous leaks were recently detected on a one-mile section of 8-inch steel pipeline that had been installed in the 1970s
Production was halted while the operator evaluated options for repair
The installation of new steel pipe would require the digging of a new trench, new permitting, up to four days of installation, welding and backfill,
at a total cost of $213,000 Moreover, corrosion management would still
be needed over the course of operation
Instead, the operator chose a pull-through rehabilitation solution offered
by Baker Hughes, the company that had pioneered the technique There would be no need to dig a new trench, no new permitting, no welding, no corrosion management, and the solution could be deployed in a single day Total cost: $89,000
A 3-inch PPS Thermoflex® pipe with a nylon inner liner and aramid reinforcement was selected Two pigs were run through the host pipeline, cleaning residual gas condensates in a process that took 2.5 hours A rope, attached to the pig, is then attached to the Thermoflex RTP, which
is then pulled back through the host pipe at 60 ft per minute End fittings were attached and the new line was tested at 1,500 psi (minimum burst pressure 4,064 psi)
The entire rehabilitation project took about five hours, providing a much lower installation cost and a lower life-cycle cost
Trang 61 Harrington, Rebecca Business Insider Here’s How Much Oil Has Spilled From US Pipelines Since 2010 December 15,
2016 URL source: http://www.businessinsider.com/how-much-oil-spills-from-pipelines-us-america-natural-gas-2016-12
2 Groeger, Lena Scientific American How Safe Are America’s 2.5 Million Miles of Pipelines? November 16, 2012
URL source: https://www.scientificamerican.com/article/how-safe-are-americas-2-5-million-miles-of-pipelines/
3 Fehling, Dave NPR StateImpact: Texas Moving Crude Relies on Aging Pipeline System September 5, 2012 URL source: https://stateimpact.npr.org/texas/2012/09/05/moving-crude-relies-on-aging-pipeline-system/
4 Groeger, Lena Scientific American How Safe Are America’s 2.5 Million Miles of Pipelines? November 16, 2012 URL source: https://www.scientificamerican.com/article/how-safe-are-americas-2-5-million-miles-of-pipelines/
5 PHMSA The State of the National Pipeline Infrastructure: A Preliminary Report U.S Department of Transportation 2011
6 Ibid
7 Ibid
8 North American Oil & Gas Pipelines Five Fixes for Aging Pipelines April 6, 2016; URL source: http://napipelines
com/5-fixes-aging-pipelines/
9 Kiefner, J., & Trench, C (December, 2001) Oil Pipeline Characteristics and Risk Factors: Illustrations from the Decade
of Construction American Institute of Petroleum 2001 URL source: http://www.api.org/~/media/files/oil-and-natural-gas/ppts/other-files/decadefinal.pdf?la=en
10 Nyborg, Rolf Controlling Internal Corrosion in Oil and Gas Pipelines Business Briefing: Exploration & Production: The Oil & Gas Review 2005 – Issue 2
11 Engber, Daniel Slate My Pipeline’s Corroded But I Thought Oil Prevented Rust August 8, 2006 URL source:
http://www.slate.com/articles/news_and_politics/explainer/2006/08/my_pipelines_corroded.html
12 Fehling, Dave NPR StateImpact: Texas Moving Crude Relies on Aging Pipeline System September 5, 2012 URL source: https://stateimpact.npr.org/texas/2012/09/05/moving-crude-relies-on-aging-pipeline-system/
13 Isidore, Chris CNN Money Spills Are More Common Thanks to Aging Pipelines September 21, 2016 URL source: http://money.cnn.com/2016/09/21/news/companies/aging-pipelines/index.html
14 Quadrennial Energy Review: Energy Transmission, Storage, and Distribution Infrastructure, April 2015, Department
of Energy URL source: https://energy.gov/sites/prod/files/2015/04/f22/QER-ALL%20FINAL_0.pdf
15 PHMSA The State of the National Pipeline Infrastructure: A Preliminary Report U.S Department of Transportation 2011
16 Dr Abdel-Alim Hashem Oil and Gas Pipeline Design, Maintenance and Repair Cairo University, Dept of Mining, Petroleum & Metallurgical Engineering URL source: http://www.eng.cu.edu.eg/users/aelsayed/Part%2011%20 Pipeline%20Rehabilitation%20and%20Repair%20Techniques.pdf)
17 Sharma, K.P Case Study: Rebabilitation of 32” Gas Pipeline in the Most Cost-Effective Way 6th Pipeline Technology Conference, 2011 URL source: https://www.pipeline-conference.com/sites/default/files/papers/Sharma.pdf
18 G.H Koch, M.P Brongers, N.G Tompson, Y.P Virmani, and J.H Payer Corrosion Cost and Preventative Strategies in the United States Federal Highway Administration, Office of Infrastructure Research and Development, pp.260-311, 2001.) Source URL: https://www.researchgate.net/publication/310518032_Systems_for_Repair_and_Rehabilitation_of_ Corroded_Oil_Gas_Pipelines
19 O’Connor, Chris The Nature of Polyethylene Pipe Failure Unconventional Oil & Gas September 27, 2016 URL Source: http://www.unconventionaloilandgas.com.au/the-nature-of-polyethylene-pipe-failure/)
Conclusion
Pipeline infrastructure in the United States is vital to industry, national security, and economic well-being However, as this aging infrastructure ages even further, so increases the likelihood of devastating oil and gas spills due to the effects of corrosion on steel
Replacing this network of pipelines is a daunting task—logistically, financially, and politically Rehabilitation, in the form of pull-through solutions, is a more viable approach with the introduction of flexible, composite pipe, which in fact offers numerous cost and performance advantages over steel
There are a variety of composite materials available on the market
Aramid-fiber reinforcement provides optimal strength, while nylon liners offer additional resistance to hydrocarbons and paraffin buildup
Ultimately, product selection should be based on a thorough evaluation
of the unique application
Trang 7Baker Hughes reserves the right to make changes in specifications and features shown herein, or discontinue the product described at any time without notice or obligation Contact your Baker Hughes representative for the most current information The Baker Hughes logo is a trademark of Baker Hughes.
2020