Above: Once material has been slit, it is rewound as strip coils on the recoiler.

Slitting line technology pushes new manufacturing plant into high gear

August 2015 - It’s a numbers game. Fluctuating crude oil and natural gas prices compelled most oil country tubular goods (OCTG) suppliers to tighten their belts. Some have chosen this point in the cycle to focus on refinancing and restructuring. Market analysts say survivors will adapt, streamline workflow and implement newer technologies. In the case of one nimble-footed manufacturer, its strategic moves netted a turnover of $200 million during its first year of operation, putting it on a fast track to becoming one of five top producers in the North American electric resistance welded OCTG market.

Turkish steel pipe manufacturer Borusan Mannesmann broke ground in 2013 to build a $148 million greenfield welded OCTG facility in Baytown, Texas—next door to Houston, a global energy powerhouse. Borusan CEO Buddy Brewer cited closer proximity to customers and access to amenities such as natural gas, cost-effective electricity and transportation as Baytown’s appeal.

A good defense 

Equipment selection was equally important. A slitting line that could handle heavy gauge, high-strength steel was at the top of Borusan’s shopping list. In a pipe mill, a slitting line anchors the ERW pipe making process and is a key step in providing quality. 

“Quality is everything when it comes to slitting,” says Borusan Slitting Supervisor Joel Brown. “It’s the first defense in a good weld. It’s the first thing that has to happen before we can even think about making good pipe. A bad weld means poor quality. We call that a leaker or a blow-out if it were to find its way onto a piece of pipe.”

Borusan quickly learned that there are only three manufacturers in the U.S. able to build a slitting line that can process 5⁄8-inch thick steel. Visits to tube mills exposed Borusan to Irving, Texas-based Delta Steel Technologies’ slitting technology. Delta designs and manufactures coil processing equipment for a range of applications. During testing of its pipe mill, a turn of events allowed Borusan to verify its good first impression of Delta’s equipment. 

“We took 20 coils to a local toll processor for testing,” Brown says. “Their slitter was rated for high-strength steel but it took the facility eight hours to process one coil. They were struggling to get it through the line before finally giving up and handing the rest of the coils back to us. The slitting was subpar.”

Borusan tried again with another toll processor in Arkansas, which owned a Delta slitter. “We got the results we were looking for,” says Brown. “There was no question we had selected the right supplier.”

Borusan installed the Delta slitting system in March 2014. Rated for a maximum material thickness of 0.625 inches and a maximum width of 76 inches, the slitting line processes steel that has yield strength of up to 100,000 psi and a tensile strength of up to 115,000 psi. Line speed can reach 300 FPM.

The Baytown facility started production in June 2014 forming pipe 4.5 inches up to 10.75 inches OD from heavy gauge, high-strength hot-rolled steel coil from three of the largest U.S. producers. Borusan also has two threading lines and a heat treatment facility at its Baytown location.

The global oil & gas market is dominated by line pipe products, which is driven by the installation of new transmission lines to move oil and gas from drilling sites to customers. OCTG pipe is considered the fastest-growing product segment due to increasing demand for high-pressure drilling applications. 

“Customers are demanding high-strength, flawless pipe that can withstand corrosion and higher pressures,” says Brown. “In four to five years the alloy strengths we’re working with today will be nothing compared to what’s coming. Borusan invested heavily in this facility and they also wanted to make sure they had the right machine for the job. The Delta slitter helps position Borusan for  future work as well as today’s jobs.”

Because Borusan sources steel from multiple suppliers, the slitter had to be able to handle material variations and chemistries. “It’s done that, [which is] a performance characteristic that speaks to the line’s reliability,” Brown says. “Meeting customer deadlines is critical for us. If the slitter isn’t working properly or breaks down the impact on our deadlines would be significant. The slitter has to be dependable because it anchors our pipe-forming process. It’s the first domino.”

Borusan loads master coils up to 76 inches wide and weighing up to 40 tons onto a pit-type coil car with multiple coil saddles. The steel is then moved to a dual cone uncoiler with an overhead hold-down system.

The right fit

“Flatness and squareness prior to slitting is critical to achieve a high quality slit edge,” says Mitch Tikhman, vice president of sales and business development for Delta. “Our system employs a five-roll straightener to make the strip flat. A crop shear cuts the coil’s head and tail. By doing this the steel is also squared prior to slitting.”

A squaring guide centers the material as it enters one of two interchangeable slitter heads. This allows the operator to set up a second head for other material while the first head is running. This increases productivity, he says, “by reducing the downtime the operator spends on changing out tooling.”

Once material is slit on the outside edge, scrap is fed to the chopper. Slit material is clamped, pushed into the recoiler and rewound back into narrow strip coils. An exit coil car moves the processed coil to a storage turnstile for transportation to storage or to the shipping bays.

“The interchangeable slitter heads reduce tooling setup downtime but they also allow us to continue processing if there is a maintenance issue,” Brown notes. “The line’s scrap choppers are built to last. 

“The 1st of May 2015 marked the first time the knives were sent in for grinding since commissioning. That was significant. Longer part life gives us a more solid run time.”

A traversing roll tension unit with dual strip separators puts control over the coils in the hands of the operators.

“Delta did a really good job of giving our operators complete control over the entire process,” says Brown. “Control over the strip is critical because it can mean the difference between good edges, a good width and ultimately a good coil versus a strip that can telescope or encounter oscillation.”

Brown credited Delta with involving Borusan “in the design-build phase [which] allowed us to provide input.” 

Borusan expects to reach full production capacity of 300,000 tons of pipe and increase its workforce of 250 to 300 employees later this year. MM