Bolting is a small part of the value of an assembly and a large part of the consequence when it fails. Subsea and offshore bolting has to survive chloride attack, crevice corrosion in the thread root, and in many cases the hydrogen generated by the cathodic protection system that is supposed to be protecting it.
Langley Alloys supplies bar to fastener manufacturers and specialist bolting houses, in the sizes and condition you need to thread and head it.
Which alloy for subsea bolting without cathodic protection?
Where there is no cathodic protection, the accepted threshold for long term seawater immersion is a PREN above 40. Alloy 32760 (F55), Alloy 32750 (F53) and Ferralium® 255-SD50 (S32550) all clear that threshold with high yield strength. Alloy 625 is the step up where corrosion resistance outweighs the strength requirement.
Which alloy for high strength and sour service bolting?
Alloy 718 and Alloy 725 where the design calls for yield strengths beyond what super duplex delivers, with Alloy K-500 for high strength seawater bolting and Alloy 925 as a lower cost alternative. All can be supplied to NACE MR0175 and ISO 15156 subject to the hardness limits the standard sets.
Which alloys are used for naval and defence bolting?
Hiduron® 130 (DTD 900/4805, DIN 2.1504) and Hiduron® 191 (DEF STAN 02-835, NES 835) are long established naval bolting materials. They offer seawater corrosion resistance, galling resistance, galvanic compatibility with other copper alloys, and very low magnetic permeability. Hiduron® 130 also keeps its impact strength down to minus 196°C.
Which alloy for non-magnetic and anti-galling fasteners?
Fermonic® 50 (UNS S20910) for non-magnetic bolting with better corrosion resistance than 316, remaining fully austenitic even after severe cold working. Fermonic® 60 (UNS S21800) for nuts and threaded components where galling on assembly and disassembly is the recurring problem. Hiduron® 130 covers cases where low magnetic permeability and seawater service are required together.
Also known as
Alloy 32760 is equivalent to UNS S32760, also known as Zeron 100®, a trademark of Rolled Alloys. Alloy 32750 is equivalent to UNS S32750, also known as SAF 2507®, a trademark of Alleima. Ferralium® 255 is the Langley Alloys trade name for UNS S32550. Fermonic® 50 and Fermonic® 60 are our designations for UNS S20910 and S21800, known elsewhere as Nitronic® 50 and Nitronic 60, trademarks of Cleveland-Cliffs (formerly AK Steel). Alloy 625, Alloy 718 and Alloy K-500 are equivalent to UNS N06625, N07718 and N05500, sold elsewhere as Inconel® 625, Inconel 718 and Monel® K-500, trademarks of Special Metals. Hiduron® 130 meets DIN 2.1504 and DTD 900/4805. Hiduron® 191 meets DEF STAN 02-835 and NES 835.
Typical fastener and bolting components
Studbolts and stud ends, hex bolts and screws, nuts, socket head cap screws, threaded rod, locking pins and dowels, tie rods, clamp and flange bolting, stab plate and connector hardware, anchor bolts and structural bolting.
Why fastener manufacturers buy from us
- Bar across the full range, in diameters suited to hot heading, cold forming and machining from solid - send us the size and we will confirm from current stock.
- DEF STAN and NES specification material for naval and defence bolting.
- Consistent, traceable supply for repeat production, with call-off arrangements against long programmes.
We supply bar to fastener manufacturers and specialist bolting houses, who thread, head and heat treat it.
