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 |
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.
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.