You will get efficient and thoughtful service from .
When using stainless steel sheet for jacketing and cladding purposes, it is essential to make sure that the quality of the screws used to secure it is just as high as the jacketing material itself. On the face of it, it would seem to make sense to use a screw of grade 304 metal with sheet of the same grade but this isn't actually the right solution as both materials are of equal strength.
Standard stainless steel self-drilling screws do not work correctly in steel sheet, whether it is stainless, galvanised or aluzinc, as they are simply not hard enough. The traditional solution is to use grade 410 screws but, though these have the requisite strength, they are vulnerable to corrosion. Bi-metallic screws are a common option: these are usually supplied as 304 grade with a carbon steel tip and silver coat. Again, corrosion is an issue here.
Grade 316 self-drilling screws have fallen from favour and are now rarely used as they will not work without pre-drilling the sheet, defeating the object. Moisture around and under the head of 304 screws make them subject to galvanic corrosion. By far the most successful solution is to use duplex screws which have been around for a while as self-tapping screws but are newly available in a self-drilling format.
Duplex screws, though with a higher initial price than other types, provide massive savings in the longer term. They are three times as hard as grade 304/316 stainless steel screws an have a high PRE value making them strongly resistant to the corrosive effects of seawater.
The duplex screws are normally supplied with a bonded metal and HNBR washers . The HNBR offers a wider temperature range than traditional EPDM or Neoprene washer they are also more resistant to chemicals and ozone. The result is an excellent waterproof seal to keep out moisture and so help and improve the prevention of CUI.
These are now successfully used by Owens Corning - Foamglas for their Pool Fire Suppression System Generation 2, used for LNG storage tanks in coastal locations such as Freeport LNG. Many of the offshore companies in Europe, have now moved to duplex screws due to the life cycle cost savings when compared to costly failures resulting in replacement cladding.
BS Stainless supply a comprehensive collection of screws with various head types and washers. Discover more on our website and get in touch with our technical team for further expert advice.
5th May 2020Posted in Product news on
Stainless steels are a class of iron-based alloys with a minimum of 12% chromium. Chromium gives a steel its ability to resist corrosion. Chromium oxide is created when chromium reacts with oxygen. This material is created during the creation of a stainless steel as a thin, invisible, and self-healing layer. Different amounts of other elements are also added to improve a stainless steel’s corrosion-resistance and strength. Red rust (iron oxide) typically finds it more difficult to penetrate a stainless steel of higher chromium concentration.
In general, there are two types of stainless-steel alloys most frequently utilized to produce stainless-steel fasteners- SAE (Society of Automotive Engineers) 304 stainless steel and 316 stainless steel. These alloys are part of the 300 family of stainless steels only to be distinguished by their differences in chemical makeup and different mechanical properties as detailed below.
This type of stainless steel has a chemical composition of 18%-20% chromium and 8%-12% nickel. Fasteners made of this alloy are usually used in piping, kitchen equipment, and automotive parts.
SAE 316 stainless steel has a chemical composition of 16-18% chromium, 10-14% nickel, and 2-3% molybdenum. Such fasteners are mainly used in boat constructions, open-air environments, and other oceanic applications.
Cold heading (cold forming) and machining are two distinct methods used to make stainless steel fasteners. Machining involves a process of using a machine, or machines, to cut, shape, and remove material in order to produce a finished item. In smaller production runs, machining is the preferable procedure for bigger fasteners. This older method results in a product that is less resilient to material fatigue.
By squeezing stainless steel wire through die and punch cavities, cold heading can shape stainless steel wire into a variety of shapes. This approach is quick and involves fewer steps overall. If necessary, the fasteners are threaded after being either machined or cold worked. Cold forming is also used for this procedure when needed. Precipitation-hardening, a type of aging that integrates low-temperature aging techniques and cold working, is then frequently used to provide more strength to stainless-steel fasteners produced through cold forming.
In addition to being "stainless," stainless steels are excellent at fighting corrosion The coating found on these fasteners keeps them from rusting, becoming black, or tarnishing, thereby extending their lifespan and toughness. They can also withstand a wide range of environmental conditions and function just as effectively in extremely cold or extremely hot temperatures. Due to their adaptability, these fasteners are the preferred option in almost all applications.
As a steel alloy, stainless steels are stronger and more durable than other steels. Additionally, stainless steel fasteners can be made to withstand higher tension loads and are more resistant to the effects of stress as a result of cyclic loading.
Because stainless-steel fasteners are so durable, they rarely require costly repairs or renovations, which lowers their life-cycle costs. Their life span will continue to extend with the development of alloy technology, making these fasteners increasingly more cost-effective over time. Additionally, mass production techniques, relatively straightforward manufacturing procedures, and less expensive input prices have made stainless-steel fasteners the most widely-used fasteners. They are a little more expensive than other attaching methods, but in the long run, they are much more cost-effective because they outperform their competitors.
Stainless-steel fasteners are often gleaming and elegant. They are suitable for use where parts are exposed on the outside, or where the screws or bolts are a part of the product's visual identity, because they do not scratch readily and may be manufactured in a variety of brush finishes. These features also make these fasteners easy to clean and low maintenance.
These are green products because stainless steels are completely recyclable. These fasteners can be recycled once they have served their purpose and retrieve the priceless alloying elements like chromium, nickel, and molybdenum. Significant energy savings are possible, and CO2 emissions are decreased through recycling.
Fast installation and removal are possible with stainless steel fasteners. Fasteners like nuts, bolts, and screws are very simple to install; all it takes is a few turns of the wrench or rotations of the screwdriver to install or remove them.
SAE 304 and SAE 316 are the most widely used stainless steel grades in fasteners. These figures relate to each product's corrosion potential and, more specifically, the quantity of molybdenum (a substance that boosts corrosion resistance) present. SAE 316 stainless steel is regarded as “marine grade” and is specifically recommended for a project that will use fasteners in a corrosive environment.
Stainless steel fasteners are available in different finishes. Typically, fasteners with polished surfaces are preferred for use in most instances, especially for external applications, due to their additional corrosion resistance.
To ensure the most beneficial outcome when purchasing stainless steel fasteners from a stainless steel fastener supplier, it is important to compare several companies using our directory of stainless steel fastener suppliers. Each stainless steel fastener supplier has a business profile page highlighting their areas of experience and capabilities, along with a contact form to directly communicate with the supplier for more information or request a quote. Review each stainless steel fastener business website using our patented website previewer to quickly learn what each business specializes in. Then, use our simple RFQ form to contact multiple stainless steel fastener companies with the same form.
Contact us to discuss your requirements of assembled roving. Our experienced sales team can help you identify the options that best suit your needs.