Alleima unveils new subsea umbilical alloy for harsh offshore oil and gas operations

March 01, 2024

(WO) – SAF 3007 is the latest addition to the growing duplex family of Alleima, a super-duplex stainless steel grade developed for subsea umbilicals. The new tube offers a safe, lighter, stronger and more efficient alternative to SAF 2507, the current standard. With superior strength, fatigue properties and excellent corrosion resistance, SAF 3007 is specifically designed to excel in harsh deepwater environments.

Alleima SAF 3007 umbilical tube

The new tube product represents the next generation of super-duplex seamless tubing developed specifically for the offshore oil and gas industry. It builds on the success of the SAF 2507 (UNS S32750), which has become the industry standard.

Strong energy demand. “Across the globe, the demand for energy is growing strong. We see a rising tide of activity in the oilfields off the coast of Brazil, in the Gulf of Mexico, North Sea and Southeast Asia. Following a dip during Covid, this new surge comes, underscoring the need for reliable, cost-efficient energy production,” says John Tokaruk, Global Product Manager for umbilical tubing at Alleima.

“As the market leader in umbilical steel tubing, we often get requests for a material matching SAF 2507 in reliability, but with reduced costs, improved fatigue life and enhanced pressure handling. SAF 3007 (UNS S83072) accomplishes all this with a ‘less is more’ approach. Thinner tube walls, thanks to its superior strength and fatigue properties, results in lower cost per meter. It offers the excellent corrosion resistance of SAF 2507, and a similar microstructure, as well as simplified welding due to thinner walls,” explains John Tokaruk.

Pioneers of super duplex. For more than 40 years, Alleima has developed modern duplex grades, which are typically more than twice as strong as standard stainless steel, with superior corrosion resistance. Within the oil and gas sector, the company has been active for more than 60 years, supporting most major oil and gas companies, fabricators and service companies.

For example, one Alleima customer in the Gulf of Mexico relies on umbilicals connected to the world’s deepest spar, moored in waters with depths of 2,450 m (8,000 ft). Under such extreme conditions, system pressures may run up to 20,000 psi or more. These “dynamic” umbilicals are floating and twisting beneath the sea surface with high stress in chloride-rich environments.

In the mid-1990s, Alleima introduced the utilization of high alloy SAF 2507 as an alternative to thermoplastic subsea umbilical tubing. In essence, umbilicals serve as a “lifeline” connecting surface installations with subsea critical infrastructure such as wellheads. They include hydraulic lines, chemical injection fluids and electrical cables for controlling and monitoring infrastructure.

160 million meters sold. The optimization of SAF 2507 for subsea umbilicals, coupled with the dedicated Alleima mill in Chomutov, Czech Republic, ensuring fully integrated production from a single melt of 80 % recycled steel in Sandviken, Sweden, guarantees high quality. The large reels, with long lengths of orbitally welded coils, soon set the industry standard. Over the past 30 years, Alleima has supplied more than 160 million m (525 million ft) to all major fabricators and applications, equal to circling the world three times.

More tungsten and chrome. “To enhance the performance of SAF 2507, we fine-tuned the chemical composition. As a result, SAF 3007 features additional chromium at 30 %, reduced molybdenum at 1 % and, for the first time, Alleima introduces tungsten at 3.4 % to the duplex family of tube alloys. The inclusion of tungsten in preference to molybdenum maintains the corrosion resistance after welding, which is crucial for the umbilical application. Taken together, these properties are ideal for ‘dynamic umbilicals’ that are floating and twisting below the ocean surface with high stress in chloride-rich environments,” says Charlotte Ulfvin, Senior R&D Researcher at Alleima.

Alleima is a global manufacturer of high value-added products in advanced stainless steels and special alloys. Since the 1960s, the company has been at the forefront of developing modern duplex grades and now offers a broad portfolio.

Lead image: Alleima SAF 3007 tube on coil

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