Low-frequency electric resistance weld

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 In 1970, the low frequency process was superseded by a high frequency ERW process which produced a higher quality weld.

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. "Oil Spill Contaminates Montana Town’s Water Supply, EPA Says".
  4. ↑ http://www.inforum.com/news/accidents/3661267-clean-water-likely-be-restored-glendive-thursday-after-oil-spill-along
  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
  7. ↑ THV 11 Staff, news source (10 July 2013). "Exxon: Cause of pipeline failure 'manufacturing defects'". Retrieved 15 January 2015.
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