Low-frequency electric resistance weld

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Low-frequency electric resistance weld, LF-ERW is Electric resistance welded (ERW) pipe manufactured by cold-forming a sheet of steel into a cylindrical shape. Current is then passed between the two edges of the steel to heat the steel to a point at which the edges are forced together to form a bond without the use of welding filler material. Initially this manufacturing process used low frequency A.C. current to heat the edges. This low frequency process was used from the 1920s until 1970. In 1970, the low frequency process was superseded by a high frequency ERW process which produced a higher quality weld.

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Over time, the welds of low frequency ERW pipe was found to be susceptible to selective seam corrosion, hook cracks, and inadequate bonding of the seams, so low frequency ERW is no longer used to manufacture pipe. The high frequency process is still being used to manufacture pipe for use in new pipeline construction. [1]

The Poplar Pipeline was built in the 1950s using pipe made with low-frequency electric resistance welds as was the Pegasus Pipeline. [2]

Poplar Pipeline

On January 19, 2015 oil from a broken pipeline seeped into the Yellowstone River, and contaminated the water supply 10 miles south of Glendive, Montana. The release was from Bridger Pipeline LLC's 12-inch Poplar line, which can carry 42,000 barrels a day of crude from the Bakken Formation and runs from Canada south to Baker, Montana. Bridger Pipeline is a subsidiary of True Cos., a privately held Wyoming-based company. The company said in a statement that the pipeline was shut down within an hour of the leak. [3] [4]

Pegasus Pipeline

The 2013 Mayflower oil spill occurred when ExxonMobil's 20-inch Pegasus crude oil pipeline spilled near Mayflower, Arkansas on March 29, causing crude to flow through yards and gutters, and towards Lake Conway. Wildlife was coated in some places. Twenty-two homes were evacuated, due to the fumes and fire hazard. Some estimates say the total amount spilled could reach upwards of 300,000 gallons diluted bitumen were spilled. Hook cracks and extremely low impact toughness in the LF-ERW seam were identified as causes of the failure. [5] [6] [7]

Notes and references

  1. ↑ "Fact Sheet: Pipe Manufacturing Process". primis.phmsa.dot.gov. U.S. Department of Transportation, Pipeline & Hazardous Materials Safety Administration. Retrieved January 25, 2015. Over time, the welds of low frequency ERW pipe was found to be susceptible to selective seam corrosion, hook cracks, and inadequate bonding of the seams, so low frequency ERW is no longer used to manufacture pipe.
  2. ↑ Elizabeth Douglass (January 22, 2015). "Ruptured Yellowstone Oil Pipeline Was Built With Faulty Welding in 1950s Poor safety, defects may have added risks to pipeline that spilled up to 40,000 gallons of oil into the Yellowstone River". InsideClimate News. InsideClimate News. Retrieved January 25, 2015.
  3. ↑ Sider, Alison (19 January 2015). "Oil Spill Contaminates Montana Town's Water Supply, EPA Says". Wall Street Journal.
  4. ↑ "Clean water likely to be restored to Glendive on Thursday after oil spill along Yellowstone | INFORUM". Archived from the original on 2016-01-28. Retrieved 2015-01-25.
  5. ↑ Visser, Nick (April 9, 2013). "Maddow Slams Exxon's 'Paper Towel' Cleanup Efforts". Huffington Post.
  6. ↑ http://www.phmsa.dot.gov/staticfiles/PHMSA/DownloadableFiles/File/4%202013%205006H_Corrective%20Action%20Order_4%2002%2013.pdf [ permanent dead link ]
  7. ↑ THV 11 Staff, news source (10 July 2013). "Exxon: Cause of pipeline failure 'manufacturing defects'". Archived from the original on 28 October 2013. Retrieved 15 January 2015.

Related Research Articles

Electric resistance welding (ERW) is a welding process where metal parts in contact are permanently joined by heating them with an electric current, melting the metal at the joint. Electric resistance welding is widely used, for example, in manufacture of steel pipe and in assembly of bodies for automobiles. The electric current can be supplied to electrodes that also apply clamping pressure, or may be induced by an external magnetic field. The electric resistance welding process can be further classified by the geometry of the weld and the method of applying pressure to the joint: spot welding, seam welding, flash welding, projection welding, for example. Some factors influencing heat or welding temperatures are the proportions of the workpieces, the metal coating or the lack of coating, the electrode materials, electrode geometry, electrode pressing force, electrical current and length of welding time. Small pools of molten metal are formed at the point of most electrical resistance as an electrical current is passed through the metal. In general, resistance welding methods are efficient and cause little pollution, but their applications are limited to relatively thin materials.

<span class="mw-page-title-main">Prudhoe Bay oil spill</span> Alaskan oil spill of 2006

The Prudhoe Bay oil spill was an oil spill that was discovered on March 2, 2006 at a pipeline owned by BP Exploration, Alaska (BPXA) in western Prudhoe Bay, Alaska. Initial estimates of the five-day leak said that up to 267,000 US gallons (6,400 bbl) were spilled over 1.9 acres (7,700 m2), making it the largest oil spill on Alaska's north slope to date. Alaska's unified command ratified the volume of crude oil spilled as 212,252 US gallons (5,053.6 bbl) in March 2008. The spill originated from a 0.25-inch (0.64 cm) hole in a 34-inch (86 cm) diameter pipeline. The pipeline was decommissioned and later replaced with a 20-inch (51 cm) diameter pipeline with its own pipeline inspection gauge (pig) launch and recovery sites for easier inspection.

<span class="mw-page-title-main">2013 Mayflower oil spill</span>

The 2013 Mayflower oil spill occurred on March 29, 2013, when the Pegasus Pipeline, owned by ExxonMobil and carrying Canadian Wabasca heavy crude from the Athabasca oil sands, ruptured in Mayflower, Arkansas, about 25 miles (40 km) northwest of Little Rock releasing about 3,190 barrels of oil. Approximately 12,000 barrels of oil and water mix was recovered. Twenty-two homes were evacuated. The United States Environmental Protection Agency (EPA) classified the leak as a major spill.

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