Marine Bolting & Fasteners

TorqBolt is engaged in manufacturing Bolts used for marine engineering. Especially Coated bolts with high density are used for Marine Environments. Size Range from ½ inch to 4 inch is manufactured for these Fasteners.

Alloy Type Brand UNS Number
2507 Super Duplex Steel Zeron 100 ‘A’/FG/FLT S32750 / S32760
255 Super Duplex Steel FERRALIUM 255 S32550
6% Mo Stainless Steel 254 SMO S31254
Stainless Steel - N08026
Stainless Steel Sanicro 28 N08028
Stainless Steel Alloy 31 N08031
Stainless Steel AL6XN N08367
Stainless Steel INCOLOY 926 N08926
Stainless Steel - N08932
59 Nickel Based Alloy Alloy 59 N06059
C276 Nickel Based Alloy HASTELLOY C276 N10276
625 Nickel Based Alloy INCONEL 625 N06625
686 Nickel Based Alloy Inconel 686 N06686
725 Nickel Based Alloy INCOLOY 725 N07725
925 Nickel Based Alloy INCOLOY 925 N09925
MP35N Nickel Based Alloy MP35N R30035

Materials used for Marine Fasteners

The alloys are super high-strength Copper Nickel Fasteners (Cu-Ni 70-30 ) and (Cu-Ni 90-10 ), Duplex Stainless steel, and Nickel based alloys. Copper-base, stainless steel, and nickel-base alloys are often specified for fasteners above the waterline. Even type 304 stainless steel is used. Below table Indicates the grades used for marine bolting depending upon the application.

Marine Engineering Bolting Materials

Marine Engineering Bolting Products

Nickel containing alloys are identified as the perfect choice materials for marine fasteners used in seawater or sea atmospheres. The marine corrosion of the alloys is briefly reviewed and Galvanic and crevice corrosion are critical conditions to consider when selecting marine Bolting & fasteners alloys. Satisfactory service performance of fasteners can be achieved in the marine environment if proper materials are chosen initially. A common indicator frequently used to rate crevice corrosion resistance of stainless steels in seawater is the pitting resistance equivalent (PREN) number. It is based on the composition of the alloy. The PRE number is a good indication of the relative resistance of Fe-Cr-Ni-Mo and Ni-Cr-Mo alloys to crevice corrosion in marine applications. These alloys should have a PRE number >40 to be considered for seawater applications, although alloys with <40 have worked. Nickel-base alloys with a PRE >60 are considered immune to crevice corrosion in seawater.
When stainless steel and nickel-base alloy fasteners are submerged (partial or fully) in seawater environments, crevice corrosion resistance is the primary limiting property. Crevice corrosion varies with alloy composition, metallurgical condition, and severity of the crevice. Many of the more highly alloyed stainless steels and nickel-base alloys, particularly those containing higher levels of Chromium, Molybdenum and nitrogen have excellent resistance to crevice corrosion in seawater.