Steel is the key to sustainable infrastructure

Line pipe development and production demonstrates cooperation

06.28.2017

When pipe lines go bad, the results can be catastrophic. An explosion or leak can cause death, destruction and environmental impacts lasting for years. As a supplier to this industry, ArcelorMittal understands how critical it is to provide safe products.

ArcelorMittal Global Research and Development engineers are developing steel which is thicker and tougher than any other steel made by hot strip producers in North America.

“The steel must be clean of defects to avoid a rupture initiation,” said Dmitri Sidorenko, lead research engineer, plate and energy market products, ArcelorMittal Global Research and Development, East Chicago. “We’ll be expected to supply steel which passes rigorous ultrasonic inspections.”  
 
In the United States, there are 185,000 miles of oil pipelines and 320,000 miles of gas pipelines. And 82,000 additional miles of new pipe line is planned to meet energy infrastructure needs.  

Line pipe has to be strong enough to handle immense pressures, especially in gas transmission – 2,000 pounds per square inch of operating pressure for typical long distance gas transmission. And for ArcelorMittal to supply line pipe steel, we must meet the standards set by the American Petroleum Institute.

CoilsSlabs are made in Mexico, Brazil and at our Indiana Harbor plant, then shipped to AM/NS Calvert. It takes a very powerful finishing mill to make line pipe.

Line pipe can be made from either steel plate or hot rolled coils. ArcelorMittal supplies both to all the major pipe producers using API 5L in the United States primarily for long distance oil and gas transmission. Plate is produced at the Burns Harbor plant and coils at AM/NS Calvert.  

At the manufacturing site, coils are cold-formed into a tube and welded into a pipe up to 48 inches in diameter and 80 feet in length.  

“Inspection is critical for the manufacturer. It’s interesting to me, that if you go to a pipe mill, the section where the pipe is actually made is fairly small. The majority of the space is used for inspections,” said Sidorenko.  

Line pipe steels made today are 34 percent stronger than pipe made in 1950s through the 1970s and have 10 times greater impact toughness.  

“While ArcelorMittal didn’t invent this type of steel, we are always tweaking it,” said Michael Mulholland, research engineer, plate and energy market products, ArcelorMittal Global Research and Development, East Chicago.  “A big difference is the carbon content. We’re taking more out now. In earlier days the mix was about 0.20 percent carbon, we’ve taken it down to 0.04 percent. Less carbon makes the steel tougher and easier to weld.”     

The transmission pipes are pressurized with gas or oil. The pressure can drop, then go back up, based on the volume of fluid inside, and that causes fatigue in the steel. If there’s an inclusion or other defect the pressure can cause a crack and that will eventually go through the wall of the pipe. 

Global Research and Development engineers are currently working on how to make the gauge heavier while increasing the toughness and strength.  

“The research piece is important, but it’s the crew at the hot strip mill that really has the pressure to perform,” added Mulholland. “It’s a very demanding product in terms of its quality and cleanliness requirement. Everything has to go right.” 

ArcelorMittal has an advantage over other mills when the gauge requirement is greater than one-half inch. AM/NS Calvert has a heavy gauge coiler which can roll one inch, and Burns Harbor can roll plate to one inch as well.  

“Calvert was making a lighter gauge, now they are learning to make thicker. We’re on site a lot to help them through the learning curve,” said Mulholland. “They encounter significant challenges with dimensional uniformity and winding. We talk to various people to understand their problems, give our recommendations then prepare for trials and observe what’s taking place. We can see when something goes wrong, and offer ideas to fix it.”  

“This is really teamwork,” concluded Sidorenko. “As researchers, we have access to the best information and can make impact quickly. We can reach out to colleagues in Europe and learn from them as well. We bring best practices to the hot mills. Employees are hesitant to push the limits, they don’t want to damage equipment – and rightly so. We do our best to explain everything to help them feel better about trying something new.”  

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