Coatings, Cathodic Protection Check Cold-Climate Corrosion.Rusty steel, blistered sheet metal, deteriorating concrete-- the effects of corrosion are not hard to find, but they can be difficult to combat. From coastal Southeast out to the Aleutian Islands Aleutian Islands (əl`shən), chain of rugged, volcanic islands curving c.1,200 mi (1,900 km) west from the tip of the Alaska Peninsula and approaching Russia's Komandorski Islands. up to the North Slope North Slope, Alaska: see Alaska North Slope. and throughout the Interior, engineers are engaged in a costly battle with corrosion on two fronts: internal environments and external environments.
Corrosion is the deterioration of a material or its properties, caused by a reaction within its environment. Wood, plastics, ceramics and metals are substances gradually destroyed by corrosion, which is measured by changes in weight, dimension or mechanical properties, such as tensile strength tensile strength
Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its ( the greatest longitudinal stress a substance can bear without tearing apart) or ductility ductility, ability of a metal to plastically deform without breaking or fracturing, with the cohesion between the molecules remaining sufficient to hold them together (see adhesion and cohesion). Ductility is important in wire drawing and sheet stamping. (capability to be molded into a new form).
Corrosion causes about $1 billion a year in damages in Alaska, according to according to
1. As stated or indicated by; on the authority of: according to historians.
2. In keeping with: according to instructions.
3. Lyle Perrigo, director of the U.S. Arctic Research Commission's Alaska Office. That cost could be as high as 6 percent of the value of goods and services In economics, economic output is divided into physical goods and intangible services. Consumption of goods and services is assumed to produce utility (unless the "good" is a "bad"). It is often used when referring to a Goods and Services Tax. produced in Alaska, but Perrigo said there are ways to cut losses.
"About 1 percent could be saved by using cathodic protection Cathodic protection (CP) is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell.
It is a method used to protect metal structures from corrosion. , by using the right kind of building materials Building materials used in the construction industry to create .
These categories of materials and products are used by and construction project managers to specify the materials and methods used for . or by using the right kinds of inhibitors. Just because you have high (corrosion rates, that doesn't mean you can't cope with it (corrosion)," Perrigo said. "We can paint more frequently, use better coatings, better designs--these are not insurmountable problems. We do not need to reinvent the wheel. We just need to figure out where it is going."
Internal environments include the interiors of oil and water pipelines, and mechanical systems. Fluids transported, or carried for lubrication lubrication, introduction of a substance between the contact surfaces of moving parts to reduce friction and to dissipate heat. A lubricant may be oil, grease, graphite, or any substance—gas, liquid, semisolid, or solid—that permits free action of , in these systems are corrosive, but corrosion in these environments can be controlled using proper materials, designs and chemical inhibitors.
"Internal corrosion is big business," according to Christopher Dash, a corrosion engineer with Phillips Alaska Inc. "Oil, water, gas and solids can eat pipes at phenomenal rates. With unprotected pipes, we're talking inches a year. And most pipes are not inches thick."
The pipes Dash is concerned about carry crude oil from drill sites to gathering sites and ultimately into the trans-Alaska oil pipeline. The pipes are 24 inches in diameter and have walls three-eighths-of-an-inch thick. They carry crude mixed with seawater seawater
Water that makes up the oceans and seas. Seawater is a complex mixture of 96.5% water, 2.5% salts, and small amounts of other substances. Much of the world's magnesium is recovered from seawater, as are large quantities of bromine. (which is pumped into oil-rich reservoirs to build pressure and force the oil out of the ground), gasses and solids.
Preventing the corrosive concoction of oil, water, gas and solids from damaging these pipes is a function of chemical inhibitors. There are about a half dozen different classifications of inhibitors, each with different applications. For use inside the crude-carrying pipes, Phillips Alaska Inc. uses an inhibitor classified as a surfactant Surfactant Definition
Surfactant is a complex naturally occurring substance made of six lipids (fats) and four proteins that is produced in the lungs. It can also be manufactured synthetically. , which finds its way to the space between the flowing substances and the inner walls of the pipes to prevent corrosion.
While chemical inhibitors successfully inhibit corrosion, Phillips monitors the effects and extent of corrosion on pipeline interiors with sophisticated sensors.
"We use a lot of ultrasonic techniques to measure pipe-wall thickness. We use a series of ultrasonic pulses that go into little radio transmitters so we can monitor what is happening at any given point, Dash said. "We cannot measure the entire pipe, so we measure areas that may be corroded cor·rode
v. cor·rod·ed, cor·rod·ing, cor·rodes
1. To destroy a metal or alloy gradually, especially by oxidation or chemical action: acid corroding metal. and we watch them."
Inline inspection is another method of monitoring pipe-wall thickness. This is accomplished by "smart pigging," Dash said. A pig is a cylindrical device that is inserted into a pipeline to clean the pipeline wall and monitor the internal condition of the pipeline. It uses an odometer odometer (ōdŏm`ĭtər), instrument provided in an automotive vehicle to indicate the total number of miles that have been traveled. to determine the location of problem areas and is capable of storing the information it gathers.
Fuel storage tanks are also affected by internal corrosion. Phillips has not had any significant leakage from its storage tanks, but Dash said the tanks are monitored. To prevent corrosion, tanks are painted inside and outside with corrosion-resistant coatings.
External environments fall into three categories, atmospheric, buried and sub-merged. Controlling corrosion in these environments is accomplished by using anti-corrosion designs, suitable building materials, protective coatings and cathodic protection.
External corrosion is also an issue on Phillips Alaska Inc. pipelines. With most of its pipelines elevated on racks above the tundra, atmospheric corrosion (attacks by airborne contaminants airborne contaminants,
n.pl materials in the atmosphere that can affect the health of persons in the same or a nearby environment. Also referred to as
air pollution. ) and under-insulation corrosion are important concerns.
When pipelines are constructed, sections of pipe are welded together. These joints are insulated, but joint integrity can be compromised at the insulated joints by water seeping under the insulation, causing under-insulation corrosion.
This form of external corrosion takes 10 years to 20 years to cause significant damage, but is very costly. Under-insulation damage costs about $5 million a year for Phillips' Kuparuk site, Dash said.
While it may take more than a decade for under-insulation corrosion to cause problems, there are examples of external corrosion that are detected much quicker.
On the Aleutian Islands, an improperly fastened, coated metal panel on a building will show signs of corrosion in as few as three years. If the fasteners used to attach these metal panels to building frames are not properly used, even coated panels have a difficult time withstanding the detrimental effects of salt-laden atmosphere of the Aleutian Chain, Perrigo said. Saltwater can seep under the fasteners and underneath coatings, causing paints to bubble or blister blister, puffy swelling of the outer skin (epidermis) caused by burn, friction, or irritants like poison ivy. A response of the body to protect deeper tissue, blisters generally contain serum, the liquid component of blood. . When water evaporates, a salty film is left behind and over time becomes more concentrated and more corrosive to metals and building panels.
In submerged environments in Alaska, corrosion occurs at some of the highest rates anywhere. Corrosion rates typically decline as water temperatures decrease, but the opposite is true in oxygen-rich waters of Alaska. Offshore oil and gas rigs in Cook Inlet Cook Inlet
Inlet, Gulf of Alaska in the northern Pacific Ocean. Bounded by the Kenai Peninsula on the east, it extends northeast for 220 mi (350 km), narrowing from 80 to 9 mi (129 to 14 km). Anchorage is situated near its head. have some of the highest corrosion rates in the world, Perrigo said.
"Every 10-degree Celsius drop reduces the corrosion rate, but oxygen propels corrosion," Perrigo said. "Cold seawater carries 50 percent more oxygen than warm seawater."
Highly oxygenated, cold seawater is largely responsible for corrosive damage in Alaska's marine environments, but abrasion from glacial silt, twice-daily tidal shifts and the action of ice floes contribute to the high rate of corrosion on Cook Inlet drilling rigs. Components of these rigs corrode cor·rode
v. cor·rod·ed, cor·rod·ing, cor·rodes
1. To destroy a metal or alloy gradually, especially by oxidation or chemical action: acid corroding metal. six times faster than their counterparts in the Gulf of Mexico Noun 1. Gulf of Mexico - an arm of the Atlantic to the south of the United States and to the east of Mexico
Golfo de Mexico
Atlantic, Atlantic Ocean - the 2nd largest ocean; separates North and South America on the west from Europe and Africa on the east .
Cathodic Protection Keeps Cold
Climate Corrosion at Bay
To combat corrosion in marine environments, allowances are made for corrosion during construction of docks, piers and offshore petroleum-production platforms, and special coatings are applied to metallic surfaces. In submerged or buried marine environments, cathodic protection is the most effective corrosion inhibitor A corrosion inhibitor is a chemical compound that, when added in small concentration, stops or slows down corrosion of metals and alloys.
A typical good corrosion inhibitor will give 95% inhibition at concentration of 80 ppm, and 90% at 40 ppm. .
The simplest form of cathodic protection is coating structures in need of safeguarding with specialized paint, according to Civil Engineer John C. Daley, with Tryck Nyman Hayes Inc.
"A good coating is the first line of defense," he said.
Cathodic protection prevents a structure, such as a buried underground storage tank An Underground Storage Tank (UST), in United States environmental law, is a tank and any underground piping connected to the tank that has at least 10 percent of its combined volume underground. , from corroding cor·rode
v. cor·rod·ed, cor·rod·ing, cor·rodes
1. To destroy a metal or alloy gradually, especially by oxidation or chemical action: acid corroding metal. by making it the cathode of a galvanic cell, Daley said. Cathodes are electrodes that practically do not corrode. Anodes are electrodes that oxidize oxidize /ox·i·dize/ (ok´si-diz) to cause to combine with oxygen or to remove hydrogen.
1. To combine with oxygen; change into an oxide.
2. and corrode. When an anode anode (ăn`ōd), electrode through which current enters an electric device. In electrolysis, it is the positive electrode in the electrolytic cell.
Terminal or electrode from which electrons leave a system. is attached to a cathode, the anode corrodes instead of the cathode.
In systems using passive cathodic protection, a magnesium plate (the anode) is welded to an underground tank (the cathode) and buried near the tank. The effect is that the buried plate corrodes while the storage tank does not. In this case, the integrity of the anode is sacrificed for that of the cathode.
In active cathodic protection, a direct current power supply is attached between the anode and the cathode, with the positive terminal connected to the anode, which corrodes as it discharges the current.
In marine environments the same principles are applied, using aluminum and zinc plates as anodes, which are suspended in seawater.
"Corrosion ends up being a really significant cost to a lot of structures," Daley said. "It's not sexy, but it is an up-front problem."
Shining a Northern Light on Corrosion
NACE NACE National Association of Colleges and Employers (Bethlehem, PA)
NACE National Association of Corrosion Engineers
NACE National Association of Catering Executives
NACE National Association of County Engineers International's Northern Area Western Region Conference
February 26-28, Hilton Anchorage
When corrosion-minded engineers from Alaska, Argentina, Australia, Canada, Norway, Russia, Sweden, Uruguay and the Lower 48 converge on the Hilton Anchorage hotel in February, cold climate corrosion is going to be a hot topic.
This month's conference is the first NACE International Protecting People, Assets, and the Environment from the Effects of Corrosion NACE International is a professional organization for the corrosion control industry established in 1943. As of 2006, there are approximately 16,003 NACE members world wide. meeting to be held in Alaska since 1996. That first meeting was held in Anchorage and drew some 218 attendees who presented 75 scholarly papers.
NACE International (formerly known as the National Association of Corrosion Engineers) divides the globe into eight geographic regions, with Alaska falling into the Western Region's Northern Area. NACE International has more than 16,000 members whose mission is to inform the world about corrosion control.
"We want to make a contribution," said Lyle Perrigo, director of the Alaska Office of the Arctic Research Commission. "We want to work on defining the cost of corrosion in Alaska. The cost of corrosion may be as high as 6 percent of the total value of goods and services produced in Alaska. And every time you have to work on a pipeline in the winter the costs escalate."
There are about 60 papers on corrosion-related topics slated for presentation during the conference's eight scheduled sessions. Engineers from Alaska will play a prominent role in the conference, presenting more than half of the papers.
Of all the papers being presented, 14 of them will address issues related to corrosion in cold climates.
There is also a session titled Cold Climate Corrosion. "That's our biggest session," said Christopher Dash, NACE International's Northern Area technical program chair.
Other sessions planned for the conference include Oil and Gas Chemical Treatments, Coatings and Linings, Inline Inspection Pigging, Cathodic Protection, Computers and Corrosion, Materials and Metallurgy, Infrastructure Corrosion, Pulp and Paper Mill Corrosion and Marine Corrosion Control.
NACE International's Northern Area is also sponsoring a photo contest to focus attention on corrosion problems. Photos may be submitted in the following categories: Impact of Corrosion on Aesthetics, Effects of Corrosion on Materials, and Effects of Cold Climates on Corrosion Control. For information, contact Lyle Perrigo at email@example.com.
The conference also will provide those in the corrosion-control industry the opportunity to display their products or services in a trade show at the Hilton Anchorage. NACE International is still looking for Looking for
In the context of general equities, this describing a buy interest in which a dealer is asked to offer stock, often involving a capital commitment. Antithesis of in touch with. financial sponsors for the technical conference and exhibitor space is still available. For details, call Chuck Clark at Polar Supply in Anchorage at 563-5000.