Offshore Oil Platform Fasteners
Offshore Stainless Supplies, the UK’s only NORSOK-approved D59 manufacturer, has a proven track record of delivering high-performance stainless steel products to the offshore oil and gas industry. Recently, OSSL was tasked with producing and supplying UNS S32760 Super Duplex strain-hardened bars for the manufacture of fasteners to meet the stringent MDS D59 Rev 3 specifications.
These fasteners were intended for use on a North Sea oil platform, where environmental conditions are among the harshest in the world. The project demanded the highest levels of material integrity, mechanical strength and corrosion resistance to ensure the platform's operational safety and longevity.


The platform’s operators required fasteners that could meet the demanding specifications of NORSOK MDS D59 Rev 3, which outlines the requirements for materials used in fasteners exposed to corrosive offshore environments. UNS S32760 Super Duplex stainless steel was chosen for its superior mechanical properties and resistance to chloride-induced corrosion, which makes it ideal for applications in offshore oil and gas platforms.
The production of the cold drawn bars involved a controlled manufacturing process to ensure that the material met both the mechanical strength and corrosion resistance criteria outlined by MDS D59. UNS S32760 is a Super Duplex stainless steel grade known for its excellent balance of strength, ductility and corrosion resistance, especially in chloride-rich environments such as seawater. It offers high resistance to stress corrosion cracking, pitting and crevice corrosion, which are common issues for offshore structures.
Quality testing played a critical role throughout the process, with the bars undergoing tensile and Charpy impact testing to confirm their mechanical properties, as well as ultrasonic testing to detect any internal defects. Additional tests for pitting and crevice corrosion resistance were conducted to ensure that the material would perform well in subsea environments.
Offshore Stainless supplied the strain-hardened bars to be used in the manufacture of a range of fasteners, including hex bolts, stud bolts, threaded rods and socket head cap screws. These fasteners were designed for critical applications on the North Sea oil platform, where they were deployed in key areas such as subsea pipeline flanges, wellhead assemblies and structural joints. The hex bolts and nuts were used to secure high-pressure pipeline connections, while stud bolts played a vital role in subsea wellheads and manifolds.
In addition to meeting the mechanical and corrosion resistance requirements of MDS D59 Rev 3, OSSL ensured that all fasteners were manufactured to precise dimensional tolerances. This was essential to guarantee a perfect fit in high-pressure and high-torque applications, where even minor discrepancies in size or alignment could lead to leaks or mechanical failure.
By delivering fasteners that comply with the NORSOK standard, Offshore Stainless has provided the platform operator with a solution that enhances the safety and longevity of the platform’s infrastructure. This project underscores the critical role that high-quality materials play in the success of offshore oil and gas operations, where reliability and durability are paramount. Through our dedication to meeting the highest industry standards, OSSL continues to be a trusted partner for offshore stainless steel solutions.