Stainless steel and the different grades in relation to rivet nuts, rivnuts and nutserts.

In this blog we will delve into the differences between 304 & 316 grade stainless- steel in relation to rivet nuts, nutserts and rivnuts.  You may not see the different grades of stainless however over time this will become apparent, especially in unforgiving applications that may involve chemical or sea salt.  In this beginner’s guide to Rivet Nuts - Stainless 304 Vs 316, we will investigate the differences between the different grades as well as suitable applications. Before we begin, let’s recap the basics. What is stainless steel? Stainless steel is an alloy; this means it is made up of a combination of elements. The key component is chromium, a trace mineral that ensures the metal does not rust. Stainless steel also contains other elements such as nitrogen, nickel, and molybdenum.

The key difference between grade 304 and grade 316 stainless steels is that 316 tends to have more nickel and a bit of molybdenum in the mix, which makes it considerably more expensive. The increased nickel content and the inclusion of molybdenum allows for grade 316 stainless steel to have better chemical resistance than the 304 stainless steel. Its ability to resist acids, chlorides, including salt, makes grade 316 ideal for numerous chemical, food, and marine applications. Most of the Huck Aerobolt range of fasteners indicate the grade of stainless including rivets, nutserts, rivnuts and so much more. 

What Are the Benefits of Stainless Steel? 

Stainless steel has numerous benefits over other metal types including corrosion resistance, durability, aesthetics and so much more.   

• Corrosion Resistance: Especially when you are using products that come into regular contact with water both in liquid and vapour form,  corrosive chemicals, food preparation or medical applications. This includes sterilization processes that involve heating with disinfectants and other cleaning chemicals. 

• Hygiene: This a high-stakes benefit, especially when it comes to restroom / bathrooms fixtures, food preparation areas, food display cabinets, and associated accessories like water coolers/bottle fillers. 

• Durability: Stainless steel is virtually indestructible and has a significant strength-to-weight advantage, making them desirable when looking for vandal-resistant options. 

• Aesthetic Appearance: This metal is attractive on its own, whether it’s polished to a high shine or has a satin finish. 

When to use stainless steel 316 over 304? 

If your application involves corrosive substances such as chloride, marine, or medical environments then paying a premium for grade 316 stainless-steel is probably worth the extra investment. In such work applications, the 316 stainless steels will last longer than 304 stainless steels—this means many extra years of useful life. For other applications where salt or water exposure isn’t a concern, the stainless steel 304 alloy can work just as well. Just be sure you’ve accounted for all processes and environmental factors when selecting the material. For instance, if the application is located on or near the coast, salty sea air can corrode metals. Overall, 316 is worth the extra expense if you need to have superior corrosion resistance. For many other applications, grade 304 stainless steel will serve well. 

Another key difference between the different grade stainless steels is the melting point of grade 304 stainless steel is a bit higher than that of grade 316. The melting range of grade 316 is 1,371 °C – 1,399 °C, roughly 50 degrees lower than the melting point of grade 304 stainless steel. Plus the tensile strength of 304 stainless steel is a little better than the 316 grade.  

What are the stainless-steel applications? 

Common applications for stainless steel: Cisterns and piping used in chemical applications, Commercial kitchens and appliances, Containers used to hold pressurized gasses or liquids, Equipment for chemical storage and processing, Equipment used for industrial and chemical transportation, Marine components, Marine settings, Medical devices and equipment not requiring surgical steel, Outdoor electrical enclosures, Outdoor furnishing, Pharmaceutical manufacturing, Refinery infrastructure, Seafood production and other food processing in saline environments. Stainless steel floats. 

What are the benefits of 316 stainless steel? 

316 grade stainless steel has several advantages over 304 stainless steel this is due to the 16% chromium, 10% Nickel and 2% molybdenum composition. The benefits include.   

Better Corrosion Resistant Properties.  

Due to the addition of molybdenum, grade 316 stainless steel is more corrosion resistant than similar alloys, such as 304 stainless steel. This reduces pitting from chemical environments and allows grade 316 stainless steel to be used in highly acidic and caustic environments that would otherwise eat away at the metal. For instance, grade 316 stainless steel can withstand caustic solutions and corrosive applications such as vapor degreasing or many other parts cleaning processes.

These properties also make grade 316 stainless steel ideal for pharmaceutical and medical applications. Since sterilization processes in these industries combine both strong disinfectants and or with high temperatures to prevent contamination, a resistant alloy such as grade 316 is ideal. 

Superior Resistance to the Effects of Salt Water.

Seawater and salt air can be especially damaging to metals. Besides the rough environment of the marine applications, chlorides, such as salt, can eat away at even the toughest metals. Salt will even compromise the protective oxide layer of grade 304 stainless steel, resulting in rust.  For marine applications, or processes involving chlorides, grade 316 stainless steel is ideal.

Grade 316 has especially better resistance to salt and chloride pitting. Pitting corrosion can occur when stainless steel alloys, such as grade 304 stainless steel, meet salt-rich sea breezes and seawater. Chloride resistant metals, like grade 16 stainless steel, are essential to use for naval applications or anything involved with chloride. 

Long Lasting Durability.    

Grade 316 stainless steel is both tough and versatile, designed to even survive repeated exposure to high impact processes.

Rivet Nut Troubleshooting Lab. 

Installing rivet nuts can sometimes not be as straightforward as we would like, so we have created a troubleshooting guide to address the most common installation issues. The pictures below show the difference between an incorrectly installed rivet nut (pictures 1 & 2) and a correctly installed rivet nut (picture 3). Before we delve into the rivet nut lab, lets cover the basics. What is a rivet nut? Rivet nuts are fundamentally an innovative captive nut that attaches onto a steel sheet surface for bolting purposes, they are ideal when a hole opening isn't possible because the material is too thin to secure a bolt. Also known as rivnut, nut inserts, or nutserts, either way they are great for punched or drilled holes, they can be installed at any stage of the production, even after paint is applied. They are an easy solution that requires a rivet nut tool (here at Aerobolt we call them nutsert tools). 

Other Rivet Nut installation issues:

Stripped thread: this is most probably caused by too much stroke or tension, or due to the tool mandrel being bent/damaged.

Tilting Rivet Nut: The quality of the rivet nut may be questionable, the tool mandrel is bent or the anvil size may not be correct. 

Scratched head: Check you have the correct size anvil on the tool.

How do you install a rivet nut?

Installing Rivet nuts is easy.   

• Step 1. Thread the rivet nut onto the mandrel of the tool, some tools spin themselves to load the rivet nut.  
• Step 2. Place the rivet nut into the pre-drilled hole & activate tool to begin swaging process. Tool’s mandrel will pull up rivet nut causing body to collapse & bulge out 360°. 
• Step 3. The rivet nut has now bulged & created a lip on the blind side of the material and has firmly interlocked itself onto the material.   
• Step 4. Rivet nut tool will either automatically or manually reverse out of the rivet nut.

What's the difference between rivet nut, rivnut & nutserts?  

Nutserts, Rivnuts, Rivet Nuts, Nut Inserts etc. are some of the different labels for fundamentally the same product. The generic label is "rivet nuts" and the other names or labels relate to different company brands and trademarks of the same product, some of these labels have become the default product name.   

What are the benefits of rivet nuts? 

Rivet nuts provide a quick, reliable, and low-cost system of inserting a thread in thin steel sheeting or tubular material. 

Key Rivet Nut Benefits.

• One side assembly for fast installations as access to the rear is not required.
• Highly resilient, forming a permanent superior thread for the attachment of a bolt/screw.
• Easy installations with minimal training. Rivet nut tools are robust & readily available.   
• Can be used to assemble two or more materials, like a rivet.
• Installs into galvanised or pre-painted material without damaging surface.
• Using rivet nuts is safer than welding with no harmful vapours, heat or dust. 
• Installs into a wide range of material gauges due to its high grip range tolerance.

What are the different type of rivet nuts? 

There are 2 main options. 

Round Body Rivet Nuts.

Round body rivet nuts are the most popular option, especially the knurled body rivet nuts (Nutsert "xtralok") due to their great resistance to spinning whilst being installed and vibration after installation. They have a low-profile wide flange head with the option of open or closed end in steel, stainless (304 & 316 grade) and aluminium. 

There are a couple of other round body options, including the smooth body rivnuts, and the slotted or split body Plus Nuts or Jack Nuts. The slotted body rivet nuts are ideal for lightweight material like plastics, fiberglass, and composites.  

Hexagon Shape Rivet Nuts.

Hexagon shaped rivet nuts are designed for use in punched hex shape holes and provide exceptional resistance to spinning (i.e. they cannot be unscrewed). Here at Aerobolt we have two options, and this includes (1) Half Hex (half hex & half round body) and (2) Full Hex shape for extra strength (predominantly hex shape body). We also have open or closed end hex rivet nuts in steel or stainless. 

SELECTING THE RIGHT TOOL FOR RIVET NUTS.

After you have selected the correct rivet nut to suit your application, you will need to consider tools. There are 3 main options that include air, cordless or manual. 

Air rivet nut tools: For frequent rivet nut installation, pneumatic (air-powered) is the easy choice. Air rivet nut tools offer fast installations with consistent results. Some of the pros include: Easy to use—the tool spins the mandrel to thread the rivet nut, then retracts to collapse the body of the rivet nut with little physical exertion required. The tool will pull to either a set pressure or a set stroke. Cons: Require an air source such as a compressor, possibly limiting mobility and making remote use impractical.

Manual rivet nut tools: For the occasional installation of rivet nuts, manual tools are your most cost-effective option. They work by adding the rivet nut to the end of the tool, squeezing/torquing, and retracting the tool from the now applied rivet nut. Some of the pros include: Inexpensive, easy concept, great for the handy person. Cons: They require physical force to use.

Cordless battery rivet nut tools: Cordless rivet nut tools run on battery power and provide incredible versatility, hence allowing you to install rivet nuts from practically anywhere. Like pneumatic tools, battery-powered tools are basically point-and-shoot. Pros: Mobility, speed. Cons: Batteries have limited charge before needing to be plugged in again, cost.

1001 RIVET NUT APPLICATIONS

Rivet nuts have 1001 uses which make them suitable for various applications such as; automotive manufacturing, aviation, balustrades, commercial kitchens, commercial furniture & fit-outs, electrical appliances & switchboards, Emergency vehicles,  Farming equipment, HVAC (Heating, ventilation & air conditioning), medical equipment, military equipment & vehicles, Playground equipment, sheet metal fabrication, solar installations, refrigeration,  RV Vehicles, Trucks & Trailers, Ute canopy bodies, Utility vehicles and so much more.  

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