SAF 3007 is the latest grade of super-duplex stainless steel designed for subsea umbilical cables, and it is part of Alleima’s expanding duplex family.
The new tube is a superior alternative to the current standard — the SAFTM 2507 — as it is safer, lighter, stronger, and more efficient. The SAF 3007 performs better in hard deepwater settings thanks to its enhanced strength, fatigue properties, and corrosion resistance.
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 market-leading SAF 2507 (UNS S32750), which has become the industry standard and further advances the duplex revolution that Alleima pioneered decades ago.
Strong energy demand
Alleima Umbilical Tubing Global Product Manager John Tokaruk said: “Across the globe, the energy demand 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.
“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 their superior strength and fatigue properties, result 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.”
Pioneers of super duplex
For more than 40 years, Alleima has been at the forefront of developing 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 metres. Under such extreme conditions, system pressures may run up to 20,000 psi or more.
These ‘dynamic’ umbilicals float and twist beneath the sea surface with high stress in chloride-rich environments — precisely the kind of harsh environments where Alleima specialises.
In the mid-1990s, Alleima pioneered the utilisation of high alloy SAF 2507 as a groundbreaking 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 optimisation 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 per cent 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 metres to all major fabricators and applications, equal to circling the world three times.
More tungsten and chrome
Alliema Senior R&D Researcher Charlotte Ulfvin said: “To enhance the performance of SAF 2507, we fine-tuned the chemical composition. As a result, SAF 3007 features additional chromium at 30 per cent, reduced molybdenum at 1 per cent and, for the first time, Alleima introduces tungsten at 3.4 per cent to the duplex family of tube alloys.
Ulfvin stated that 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.”
Due to the refined chemical composition, the company can provide a lighter tube that streamlines the entire manufacturing process and the product will be made available in a broad size range by the end of 2024.
