Fastener Standards & Specifications Guide

Stainless Steel Fasteners

As one of the largest manufacturers, our main specialization is the production of Stainless Steel Fasteners. Stainless steel has been the most preferred material for general corrosion resistance and durability in construction, water treatment, and food processing applications. These fasteners are manufactured in austenitic materials, 304, 304L, 316 and 316L depending on the applications, and these metals have good resistance to oxidation. We have Hex Bolts, Socket head cap Screws, and Threaded Rods that are made according to the standards of ASTM A193 and ASTM A320. Strain-hardened versions are also available to environments that demand greater strength as well as resistance to corrosion.

Duplex Steel Fasteners

In the cases where standard stainless steel is insufficient, especially in chloride-containing environments, we do supply high-quality Duplex Steel Fasteners. They have a microstructure that is about 50% ferritic and 50% austenitic, which gives them greater yield strength and is better resistant to stress corrosion cracking (SCC) than 300-series stainless steels. We deal in UNS S31803 and S32205 grades, which are mostly applied in chemical tankers, desalination plants and offshore oil platforms where structural integrity is not a bargain.

Super Duplex Steel Fasteners

Unifit Fastener sells the Super Duplex Steel Fasteners where extreme resistance is required against corrosion in extreme conditions, such as in subsea piping and heat exchangers. These fasteners are mainly manufactured using UNS S32750 and S32760 grades, and they have good pitting and crevice resistance. They are used in the Oil and Gas industry as the preferred choice of subsea products such as subsea manifolds and flowlines. The manufacturing process is considered balanced throughout the heat treatment to avoid embrittlement quality which will be long-time reliable in critical infrastructure.

Inconel Fasteners

We are a specialized manufacturer of Nickel-Chromium-based Inconel 600 Fasteners and other grades of Inconel 600 used in high temperatures. The Inconel family is known to maintain strength even at high temperatures when other metals would be subjected to oxidation or creep. We have Inconel 601 Fasteners that are utilized in thermal processing equipment and Inconel 625 Fasteners which are widely used due to the excellent fatigue strength and resistance to corrosion. Inconel X-750 fasteners are manufactured in cases where gas turbine parts or nuclear reactors are to be used and necessitate precipitation-hardenable alloys.

Incoloy Fasteners

Our products include Incoloy 825 Fasteners, which is a nickel-iron-chromium alloy, and also added with molybdenum and copper, and that is one of our products. These fasteners are designed specifically to offer resistance to reducing and oxidizing acids, stress-corrosion cracking, and localized attack like pitting and crevice corrosion. They find wide application in chemical processing, pollution control, and oil and gas recovery equipment that operates in a sulfuric and phosphoric acid environment.

Monel Fasteners

In the case of marine engineering and chemical processing, Unifit Fastener is the supplier of Monel Fasteners mainly in 400 and K500 grades. The Monel 400 is an alloy that is in the solid-solution state and can only be hardened through cold working and has high strength and toughness with a broad range of temperatures. It is practically resistant to stress corrosion cracking of chloride ions in the normal environment. Monel K500 contains additional aluminum and titanium that are age hardened, which give it even more strength and hardness, which is the best to use when it comes to marine shafts and pump valves.

Hastelloy Fasteners

Hastelloy Fasteners manufactured by us are used in the toughest industry conditions. Hastelloy grades such as hastelloy C276, C22, and B2 are known to be versatile, giving them unmatched resistance to strong acids such as hydrochloric and sulfuric acid. These fasteners play a vital role in flue gas desulfurization, pharmaceutical plants and petrochemical plants. These high-value alloys need to be of chemical integrity during forging and machining; that is why we have a high quality control.

Nickel Fasteners

Our capability extends to pure Nickel Alloy Fasteners, typically Nickel 200 and 201. These commercially pure wrought nickel grades have good mechanical properties and excellent resistance to many corrosive environments, particularly alkalis like caustic soda. They are frequently employed in food processing, synthetic fiber production, and structural applications where magnetic properties must be minimized.

Copper Nickel Fasteners

In the case of seawater, we are offering Copper Nickel 70/30 Fasteners and Copper Nickel 90/10 Fasteners. These alloys of Cu-Ni are very resistant to biofouling and marine corrosion. They are the piping, heat exchanger and condenser standards in saltwater systems. These grades are enriched with iron and manganese to enhance their ability to resist high velocity water impingement to guarantee serviceability in naval and offshore cooling systems.

Alloy Steel Fasteners

We produce Alloy Steel Fasteners for high-pressure and high-temperature service. The most popular in this group are the ASTM A193 Grades B7 and B16 stud bolts used in the petrochemical industry to make flanged connections. These are heat-treated fasteners that have great tensile strength and impact resistance. We also make sure that we do the threading very accurately and that we follow the hardness requirements to the letter to avoid load breakdown.

High Tensile Fasteners

We are a reliable supplier of High Tensile Fasteners, as per ISO/DIN standards, usually of 8.8, 10.9, and 12.9 grades. These fasteners are subjected to a torturous process of quenching and tempering in order to have high ratios of strength to weight. They are needed in heavy machinery, car manufacturing, and the construction of buildings made of structural steel and the bolts that used to hold them together would be deformed or sheared if normal mild steel bolts. We also come with these in many finishes, such as black oxide, zinc-plating, and hot-dip galvanizing.

Titanium Fasteners

In our case, Titanium Fasteners are manufactured when the strength-to-weight ratios and the corrosion immunity are extremely high in the application. We are selling Titanium Grade 2 Fasteners (commercially pure) and Grade 5 (Ti-6Al-4V) that are used in aerospace and high-performance automotive applications. Titanium is insensitive to chlorides, hypochlorites and wet chlorine gas and therefore these fasteners can be used in pulp and paper bleaching plants and desalination plants.

Special Alloy Fasteners

In addition to standard grades, Unifit Fastener also has an excellent performance in producing Special Alloy Fasteners. These are precipitation-hardening stainless steels such as 17-4PH, Nitronic grades and other exotic formulations that are client specific. Our engineering department liaises with customers to source and machine such rare materials so that even the most niche specifications in the project are achieved with accuracy.

Coated Fasteners

We also provide a range of surface treatments in order to increase service life in difficult environments. Our PTFE / Teflon Coated Fasteners have low coefficient of friction, hence, maintain a consistent relationship between torque and tension and can easily disassemble after years of use. We also stock Xylan Coated Fasteners which have a high salt spray and chemical resistance. Such finishes are especially useful in offshore structures where maintenance is challenging and expensive.

Fastener Standards & Specifications

Our production process is based on adherence to the international standards. Unifit Fastener manufactures fasteners to the most familiar engineering standards worldwide, which guarantees compatibility, traceability, and safety throughout international undertakings.

ASTM Standards (American Society for Testing and Materials)

ASTM standards define material grades, chemical composition, mechanical properties, and testing methods. Key ASTM standards we manufacture to include:

• ASTM A193: Alloy steel and stainless steel bolting for high-temperature or high-pressure service. Common grades include B7 (chromium-molybdenum alloy steel), B8 Class 1 & 2 (304/316 stainless steel), B16 (chromium-molybdenum-vanadium), and B8M (316 stainless steel). These are extensively used in petrochemical flanges, pressure vessels, and piping.
• ASTM A194: Carbon and alloy steel nuts for bolts used in high-pressure and high-temperature service. Grades include 2H (carbon steel), 2HM (modified carbon steel), 4, 7, 7M, 8, 8M, and others matched to bolt grades.
• ASTM A320: Alloy steel and stainless steel bolting materials for low-temperature service down to -196°C. Grades L7, L43, B8, B8M are used in cryogenic applications like LNG plants.
• ASTM A307: Carbon steel bolts and studs for general applications, available in Grades A, B, and C.
• ASTM A325: Structural bolts for steel-to-steel connections in buildings and bridges, heat-treated for high strength.
• ASTM A490: Heat-treated alloy steel structural bolts with higher strength than A325, used in critical structural joints.
• ASTM F593: Stainless steel bolts, hex cap screws, and studs for general use.
• ASTM F594: Stainless steel nuts for general applications.