What is Stainless Steel?

*This is the fourth in a four-part series about steel used in rigging supplies and rigging hardware. Visit US Cargo Control to see our entire selection of rigging supplies & rigging hardware

image of stainless steel rigging hook from USCargoControl.com

There are many different types of stainless steel, and it might be the most commonly known form of steel because even the name sounds strong and pure.  Stainless steel is a form of alloy steel but instead of being mixed with carbon, it is mixed with chromium – and in fact is usually even more than 10% chromium.  While there is some carbon in stainless steel, it is an extremely low percentage.

What sets stainless steel apart?

Stainless steel is known for being incredibly rust resistant, even more so than zinc-covered steel.  This type of resistance is inherent, so it won’t flake away like carbon steel can over time.  It has what can best be described as a “self-healing” surface.

Stainless steel classifications

There are many different classifications of stainless steel, and each one has different properties of note. The four major classifications of stainless steel include:

  • 200 Series Austenitic
  • 300 Series Austenitic
  • 400 Series Ferritic
  • 400 Series Martensitic

These four series aren’t just by themselves.  Each one has a variety of alloys.  The 200 series has five alloys, the 300 series has 15 alloys, the 400 series Ferritic has eight alloys, while the 400 series Martensitic also has eight alloys.

Stainless steel in rigging

The two main forms of stainless steel used for rigging are type 304 and 316, both from the 300 Series Austenitic.  These alloys are a chromium-nickel alloy of stainless steel that is known for its extremely high strength, resistance to corrosion, and for being non-magnetic.  The T304 offers excellent corrosion resistance so it’s a popular choice for rigging applications. However, the T316 is the preferred choice for coastal areas or when saltwater is involved.

Corrosion risks

Galvanic corrosion
Galvanic corrosion

While stainless steel offers superior corrosion resistance over regular metals, there are situations where stainless steel can corrode despite its natural tendency not to.

Pitting. Corrosion from pitting is a localized form that can result from extended exposure to particular environment- specifically those that contain chlorides.

Crevice.  Another localized type of corrosion, this can occur if oxygen levels are low in a crevice area. This is most common in nuts, washers, screw threads, and bolt shanks.

Galvlanic. This type of stainless steel corrosion can happen when metals that have dissimilar properties come in contact within a common environment such as condensation, rain, etc. The extent of the corrosion will vary with a variety of factors (temperatures, surface areas, etc.).  To illustrate, a common example is with stainless steel and aluminum. Side by side in a dry environment, these metals will not react to each other. However, when side by and side and exposed to rain, corrosion will occur. A sealant or primer can be applied to keep the water from penetrating and interacting between the two surfaces.

Stress cracks. Corrosion based from stress cracking combines both specific environments and tensile stresses.

For more information on steel used in the rigging industry, see:

 

 

What Is Alloy Steel?

*This is the third in a four-part series about steel used in rigging supplies and rigging hardware.

Alloy steel refers to any steel that is combined with a variety of metals or minerals into alloys to make it stronger or better.  While technically all steel is an alloy, including carbon steel, when someone refers to alloy steel, they are referring to a very specific type of combination or process.  While the other metals or ingredients can vary from one blend to another, the most common element that is mixed with the steel is manganese.  This is a blend that is popular because of its ability to remain sturdy but also allows the steel to be worked, molded, and used for a variety of applications.

Is manganese the only blend used?

No.  When it comes to steel, chromium, for example, is the most common mixture that is used to make stainless steel.  Obviously, zinc is applied to steel in a variety of ways, and copper, titanium, and lead are just a few of the other common alloy elements that are used to both increase strength and to help fight the brittleness that many types of untreated steel display.

The actual properties of the steel alloys will vary greatly depending on what mixture is used.  Some may cause the steel to be much more malleable, others make it more resistant to saltwater and coastal environments, while other combinations may be going for pure strength.

So what’s the big difference between alloy steel and carbon steel?

carbon steel twin clevis link from USCargoControl.com
Drop forged carbon steel connecting link with zinc plating and alloy steel pins.

Both processes are used specifically to make steel both harder and stronger – the resulting durability is definitely a big plus.  However, the differences are:

  • Carbon steel must have additional protection against rust, whereas alloy steel can create steel that is resistant to rust and corrosion without any further help or galvanization.
  • Carbon steel is less expensive and is designed more with the percentage of carbon in mind and not so much for specific properties or use, whereas alloy blends are distinctly looked at to meet specific mechanical properties with an eye to practical use.
  • Carbon steel will also be more limited by its very nature, whereas a nearly endless series of combinations for creating a steel alloy means a wide range of specific applications can be met.

For more information on steel, see:

Examining the 4 Types of Carbon Steel and  Why Add Zinc to Steel?

Why Add Zinc to Steel?

*This is the second in a four-part series about steel used in rigging supplies and rigging hardware.

Details_of_rigAs explained in the previous post about carbon steel, there are four main types, and two of those involve a layer to add zinc to steel. These two types are hot galvanized dipped and zinc plated. Both of these styles are extremely popular, and it’s not hard to see why. There are several benefits to doing things this way, but one of the most obvious is that steel can be extremely vulnerable to rust, especially in areas with a heavy exposure to saltwater. Zinc acts as a natural barrier to rust, making the steel more durable to conditions that might otherwise begin to chip away at it.

Why add zinc to steel?

Aside from the obvious benefit of inhibiting rust and protecting the carbon steel underneath, zinc actually does this by oxidizing itself. Think of it as almost as “self-sacrifice” by the zinc that keeps the steel strong. This dramatically increases the life span of the steel, as well. It’s a very short process that takes only minutes to do, and since zinc is common and inexpensive, it’s a natural fit to combine with the steel needed to build a wide variety of goods.

Which is better: hot dipped galvanized steel or zinc coated steel?

There are pros and cons to going either direction.

hot dipped galHot dipped galvanized coatings may not look as smooth but they tend to last a lot longer. Also, the zinc oxidizes before the steel which means that raw steel is still in better shape to hold up against decay. It lasts a very long time and looks more rugged, but it is also more expensive than a simple zinc coating.

 

 

zinc platedZinc coated carbon steel is more economical since it is inexpensive. However the coating is much lighter than with hot dipped steel, so the coating will wear away much more quickly – no seventy years of coating here. It does look cleaner and a lot smoother if appearance matters.

 

 

Which should you choose?

Not everyone needs the additional sturdiness or durability that comes with a zinc alloy being added to carbon steel, however most people like the idea of making sure their investment is much more likely to rust or buckle under the pressure of time. While people may disagree over which method is best for them, there’s no question that zinc is a welcome addition to carbon steel in most instances, and the decision towards one or the other will depend on the applications the zinc-coated equipment will be used in.

 

Examining the 4 Types of Carbon Steel

*This is the first in a four-part series about steel used in rigging supplies and rigging hardware.

Steel isn’t a cut and dry subject like many people tend to believe.  While most think of steel as a single strong metal and that’s it, the truth is there are three common types of steel seen in the rigging industry alone: carbon steel, alloy steel, and stainless steel.  While having three might not sound complicated at all, they break down and separate even more.

So what exactly is carbon steel?

Carbon steel is the most common type of steel by far and that’s not just in the industry.  Carbon steel is the most widely produced steel in the world.  Any steel that has .12% to 2.0% carbon added is able to be classified as carbon steel.  The particular type of carbon steel most likely used in construction or industry will depend directly on what your needs are.

There are four types of carbon steel:

1. Hot dipped galvanized

2. Painted

3. Self colored

4. Zinc-coated

Hot dipped galvanized steel

hot dip galvThis type of carbon steel is the most common form of coating on any US Cargo Control rigging items such as rigging shackles.  You can tell this type of steel because it tends to have a rough look.  The zinc coating is not smooth or precise.  However that coating also allows it to last a very long time.   On the plus side this helps prevent structural decay, can last up to 70 years, and is cheaper than stainless steel.  The cons?  This won’t last in salt water and the zinc can react differently in some environments making it less than ideal.

 

Painted steel

paintedPainted steel is simply self-colored steel that is layered with rust resistant paint.  It’s what many consider the normal end result of self-colored or plated carbon steel.

 

 

Self-colored steel

two toneSelf colored refers to a plain carbon steel that has a very thin coating of protectant applied at a factory.  The plating allows for a specific color or set of colors to then be added on. This plating doesn’t affect the strength at all but it does protect from rust as well as sets it up to be painted in custom colors.  This is actually a pretty common choice.

 

 

 

Zinc-coated steel

zinc coatedThis type of steel is also commonly referred to as anodized steel or electro-galvanized steel, so if you hear either of these two, it’s referring to the same thing. This is another way of combining zinc with steel, but this is a more controlled process that allows for a much smoother and clean finish.  It looks and feels better, but the downside is that the zinc doesn’t last as long compared to being galvanized.

 

 

How to Use Wire Rope Clips

A wire rope clip, sometimes called a u-bolt clamp or u-bolt clip is used to clamp the loose end of a length of wire rope, once it has been looped back to form an eye. These fittings consist of a u-bolt and has a saddle secured by two nuts. Generally, wire rope assemblies need at least two or three wire rope clips to secure the ends properly to the length of the rope.

Drop forged wire rope clips vs. malleable wire rope clips

image of wire rope clips from US Cargo ControlWhile wire rope clips are not designed to be used in an overhead lifting situation (swage sleeves should be used instead), drop forged wire rope clips are a heavy duty wire rope clip that can be used for sustaining overhead loads. Examples include guy lines, support lines, scaffolding, etc. Drop forged clips are galvanized, meaning they have a heavy coating of a zinc solution that will hold up to worksite abuse and the elements for a long time. Drop forged steel are excellent for use as guy wire clamps for heavy duty guying applications because they are both strong and resistant to corrosion.

Malleable Clips are a light duty wire rope clip and are not for anything overhead. As the name “malleable” indicates, it is a softer wire rope clip, thus a lighter duty option. They can be used for fences and other applications that do not sustain loads overhead.

Overhead lifting vs. sustaining overhead loads

The ‘overhead lifting’ versus ‘sustaining overhead loads’ can be confusing, but a good rule of thumb to ask is: “Is the object being moved or being held in place?” If it is being moved, then wire rope clips are not to be used. If it is being held in place, then the next question is: Is it above ground (suspended from ceiling, an awning, scaffolding, etc…) or will it be on a fence or on another object near the ground? If it is above ground, heavy duty drop forged is the best choice. If on a fence near the ground, malleable clips are acceptable.

It’s important to note that wire rope clips diminish the working load limit of the wire rope to generally about 80% of its original strength.

How to use wire rope clips

The proper way to use wire rope clips can be remembered this way: “Never saddle a dead horse.” The saddle of the clip is the piece that fits into the U bolt. The dead end of a wire rope is the end of the eye that contains the cut side. The U bolt should always be in contact with the dead end, while the saddle should be on the live end. To see a video demonstration, see our post on How to Safely Apply Wire Rope Clips to Wire Rope Assemblies.

wire rope image

 

How to Choose a Boat Sling

image of boat strapsIt might not feel like spring in many parts of the country, but we’re more than ready for warm weather and fun on the water.

If you’ll be in the market for a boat sling this summer, we just made it a little easier to find one. We’ve updated our boat lift slings page with a simple form to request a quote for a custom boat sling. Whether you’re looking for a smaller sling for a canoe or kayak, etc., have a larger sailboat or fishing boat, or even need an industrial-strength boat sling like the one shown here, we can make one to fit your needs.

You can see our new boat lifting slings quote request form on our page: Boat Slings & Boat Lift Straps page.

Because there are so many varieties, sizes and options available for a boat sling lift, each sling is custom-made to a customer’s exact specifications. Keep in mind that not all boats are recommended to be lifted with slings; you should first consult with the manufacturer of the boat for proper instruction. When deciding on the right boat lift sling for your needs, there are a few major choices to take into consideration, plus many add-on options as well.

Nylon boat straps or polyester boat straps?

Polyester is a popular choice for a sling boat lift because of it stretches very little, providing more control than nylon, which can have a “snap back” effect when under load. Polyester stretches just 3% at working load limit, and maintains 100% of the work load limit even when wet. Nylon stretches approximately 6-8% under load and can lose 15% of its working load limit when wet. Both polyester and nylon are tough, durable fabrics but it’s important to consider the environmental conditions: polyester is resistant to acids that are typically used to clean the hulls of boats. However, nylon is a better choice if the webbing will be exposed to caustic materials.

Number of plys

The number of plys needed for your boat sling will be determined by the type of boat and the weight of the boat. Typically, smaller recreational boats require just one or two plys of webbing, while larger boats will need up to four plys.

Other options for boat lift straps

image of boat sling

Chine sleeves. Also sometimes called boat pads, these sliding pads can be moved to protect rub rails and boat chines when the boat is being lifted.

Keel pad. This extra sleeve of webbing protects the sling from abrasions or cuts during a lift. Lead weights can also be sewn into the pad, so the sling will sink when it’s placed on the water.

Edge guard. Wear-resistant material is applied to the sling’s edges as a way to extend the life of the sling.

Disconnects. Allows the sling to be removed from the boat without having to detach the boat sling from the lifting device.

Knowing how to choose a boat lifting sling can be confusing, especially with so many options available. If you have any questions, don’t hesitate to call our product specialists at 800-660-3585– they’ll be glad to help.

 

How to Choose a Lifting Sling

Choosing the right sling for lighting can be confusing, but it’s important to take the environment and conditions where the lifting sling will be used into consideration.

Nylon lifting sling

image of nylon lifting sling from US Cargo Control

Nylon lifting slings are a popular choice because of their multi-purpose uses. A nylon web sling is unaffected by petroleum products like grease and oil. Nylon slings are also resilient to specific chemicals including ethers, strong alkalies and aldehydes. Nylon webbing is not a good choice for uses involving bleaching agents or acids, or for use in temperatures over 194 degrees Fahrenheit (90 degrees Celsius). Nylon also stretches at approximately 8-10%, so it should not be used when elongation is not intended.

 

Polyester lifting sling

Polyester Round Eye & Eye Lifting Sling

Like a nylon lifting straps, polyester round slings also have temperature guidelines, and are not advised for use in temperatures over 194 degrees Fahrenheit (90 degrees Celsius). Unlike nylon, they will stretch only approximately 3% of its rated capacity. A polyester round sling can handle acidic environments because the fabric is not affected by bleaching agents or common acids. Polyester webbing, however, should not be used if it will come in contact with sulfuric acids or alkaline.

 

Chain lifting sling

Image of Double Leg Chain Sling from US Cargo Control

Chain lifting slings are ideal for rugged environments and jobs. They resist abrasions, cutting and can maintain their strength and integrity even in extremely high temperatures up to 400 degrees Fahrenheit (204 degree Celsius). Chain slings are generally constructed in Grade 80 steel, but a Grade 100 chain is usually available on request. Grade 100 chain offers more strength (about 25% more) for lifting chains, yet weighs less than traditional Grade 80 lift chains. Another benefit of a chain sling is its ability to be customized for almost any type of lift. However, a chain hoist can be expensive and the prices can vary due to the market fluctuations.

 

Wire rope lifting sling

image of Wire Rope Lifting Sling from US Cargo Control

Wire rope slings are similar to a chain sling in that it offers excellent durability, strength and resistance to high temperatures. Wire rope, however, is more cost-efficient than chain so it’s a great choice is price is a concern. Because abrasion-resistance and flexibility of the wire rope can change depending on its configuration, a chain sling can be manufactured using a specific type of wire rope. Typically, wire rope is made from either 6×19 or 6×37 classes of rope. A 6×19 is the most widely used because of its ideal combination of flexibility and abrasion resistance. A 6×37 class rope is more flexible, but offers less resistance to abrasion.

 

Other factors will go into determining which lifting sling type is best for your specific job, such as the item(s) being lifted, capacities needed, etc. For help choosing a lift sling, call our product specialists at 800-660-3585. They’ll be happy to any answer questions you may have.

Wire Rope Clips and Safety

At US Cargo Control we offer a variety of wire rope clips. It is crazy that such a simple device could be so complicated! There are multiple types of wire rope clips for different applications and there is a right way to use them. Hopefully this clears up some issues on how to use a wire rope clip and what type of wire rope clamp is right for you. More information about the products and the types of clips are also available on our website.

Wire Rope Clip Safety

Wire rope clamps are used to secure the ends of wire rope but it is important to use the steel clamps in a way that secures the rope. The saddle and the nuts should be on the opposite side from the terminated end. In other words, make sure that all of the wire rope clamps are on the same side and that the loops are on the side of the terminated end. For more information on how to tie down wire rope, please call our product experts at 800-660-3585.

Drop Forged vs. Malleable Wire Rope Clips

The wire rope clip strength  is one of the most important factors in determining which type is best for your application. Drop forged steel cable clamps are designed for heavy duty applications. Drop forged steel is strong because the process of pressing the hot steel into dies creates one piece of strong steel. Malleable wire rope clips are designed for lighter loads but offer considerable cost advantages. Applications that malleable wire rope clamps can be used for include fencing, guard rails, hand rails, etc. As a rule of thumb, if it is an overhead or critical system, drop forged or precision cast steel wire rope clips should be used.