1. 3 basics symbol You Must Know on your lifting rigging hardware
Do you know random numbers or symbols on your lifting equipment? We’d like to reveal 3 “basic” customers MUST be aware of when using rigging hardware, chain, and lifting slings.
What Does Working Load Limit Mean?
Working load limit is also known as safety working load, abbreviated as W.L.L, it is the maximum safe working load that a piece of lifting equipment, without fear of breaking. It usually varies based on what type of rigging or safety equipment and are identified by manufacturers.
Minimum Breaking Strength
The minimum break strength aka Minimum Breaking Load (MBL) refers to the required force at which your load equipment will fail. It is expressed in pounds, and/or tonnes, and will actually fail if you go over the guaranteed strength.
The safety factor is the ratio between the minimum breaking strength and the working load limit.
It is a calculation of the Minimum Breaking Strength (MBS) aka Minimum Breaking Load (MBL) divided by Working Load Limit (WLL)
SF = MBL / WLL
So if a shackle has a WLL of 1 ton, would have a SWL or MBS of 4 tons if a safety factor of 4 (4:1, 4 to 1, or 1/4) is used, usually the safety factor ranging from 4 to 6 on lifting equipment.
2. 3 Common Types Of Steel Materials In The Rigging Industry
There are many different types of steel materials used in rigging supplies and rigging hardware, while there are three commonly known forms of steel materials seen in the rigging industry alone: carbon steel, alloy steel, and stainless steel.
Carbon steel is the most widely produced steel in the world, characterized by high carbon content, usually, any steel with carbon content from about 0.05% up to 2.1% by weight can be defined of carbon steel, stated from the American Iron and Steel Institute (AISI), it is the most common type of steel by far and not just in the rigging hardware products.
How many types of carbon steel:
1. Low-carbon steel
0.05 to 0.25% carbon (plain carbon steel) content.
2. Medium-carbon steel
Approximately 0.3–0.6% carbon content.Balances ductility and strength and has good wear resistance; used for large parts, forging and automotive components, commonly most of the drop forged shackles, turnbuckles, or any other need heat treatment rigging items are made in Medium carbon steel (C1045). You can click this link to check our rigging items.
3. High-carbon steel
Approximately 0.26 to 1.00% carbon content. Very strong, used for springs, edged tools, and high-strength wires
4. Ultra-high-carbon steel
Approximately 1.25–2.0% carbon content. Steels that can be tempered to great hardness. Used for special purposes like (non-industrial-purpose) knives, axles or punches. Most steels with more than 2.5% carbon content are made using powder metallurgy.
In the rigging industry, the most commonly produced type of carbon steel is low carbon steel and medium carbon steel, because they can be formed very easily due to the right wt% C, and after heat treating(Quenched & Tempered), their mechanical properties will be changed to ductility, hardness, yield strength, or impact resistance.
Alloy steel is steel that is alloyed with a variety of elements to improve its mechanical properties. Most commonly, all steel is an alloy, including carbon steel, while in the rigging industry field, the phrase “alloy steel” refers to a very specific type of carbon steel, combined with the element, manganese, chromium, or both, this increased strength and to help fight the brittleness that many types of untreated steel display, especially after the heat treatment. It is used in our Grade 8/80 & Grade 10/100 Components.
Stainless steel also known as inox steel (meaning inoxidizable from the French word inoxydable), is actually a type of alloy steel mixed with a minimum of approximately 11% chromium, nickel, molybdenum, and extremely low carbon as one of its elements. The other alloying elements may vary according to the structural and chemical properties required for the stainless steel.
One of the major positives of stainless steel is that it never easily corrodes due to the presence of chromium, which prevents the steel from rusting.
It is used in a wide range of applications from automobiles to shipping components and consumer products to bulk material and handling equipment. There are a number of standard alloys of stainless steel.
Specific types of stainless steel are often designated by a three-digit number in the rigging industry, commonly there are two types of stainless steel used for rigging, 304 stainless and 316 stainless steel, the 304 stainless steel is better and more expensive than 316 stainless steel for it adds molybdenum, which has excellent resistance to pitting corrosion, while the 316 marine grade stainless steel hardware is the preferred choice for coastal areas or when saltwater is involved.
What’s the difference between carbon steel, alloy steel and stainless steel?
Stainless steel has a high chromium content, the chromium can be exposed to oxygen without developing rust or corrosion, making a protective layer of chromium that creates a barrier between environmental oxygen and the metal’s iron content.
Normally, when carbon steel is exposed to moisture, it undergoes a chemical transformation, known as oxidation, that changes their properties, although stronger and more durable, if there is no additional protection against rust on the surface, such as hot dipped galvanized, zinc plated or painted.
Carbon steel and alloy steel are stronger and harder than stainless steel for high carbon content changes the characteristics of steel, whereas alloy steel is the strongest of the three, for its includes element, manganese, chromium, modify the properties of the metal, especially after the Quanched and Tempered, and it can resistant to rust and corrosion without galvanization.
Although carbon steel lacks the corrosion-resistant properties of its stainless steel counterpart, and not stronger and harder than alloy steel, it is less expensive and can create a wide range of steel alloy specific applications by adding the element combinations.
3. Surface Finish: 4 Common Types You Should Know
You may find many types of surface finishing in your rigging items, hot dipped galvanized shackles, painted hoist hooks, or zinc plated chains. Surface finishing is essential for the practical use of steel. When left unprotected, the steel will react with oxygen to form rust. This means that colorful exteriors aren’t just decorative—they are functional barriers that prevent corrosion.
Here in this article, we will help you understand the common types of surface finishing used in rigging industry.
Hot dipped galvanized is a form of galvanization, it is the most common form of surface finishing on the rigging items, with a rough look, not very smooth and precise, although it is considered superior in terms of cost compared with stainless steel, and can protect the carbon steel underneath from further corrosion in many circumstances, but don’t last a very long time in salt water, it is usually used for the safety factor 6 times W.L.L forged shackles.
Zinc-coated, also called zinc-plated, galvanised, or electro galvanized, It is another way applying a protective zinc coating to steel or iron, to prevent rusting, but this is a more controlled process that allows for a much smoother and looks better than hot dipped galvanized, but the zinc plated doesn’t last as long compared to being hot dipped galvanized.
Painted steel is commonly layered with rust resistant paint to the self-colored steel with a painted gun, once the painted coating reaches the desired thickness, the rigging items are placed in a curing oven, the curing creates thermal bonds between paint particles, resulting in a smooth, beautiful and hard finish, please find the common painted coated rigging hooks for your understanding.
Self colored refers to a plain carbon steel that has a very thin coating of protectant applied at a factory, we usually add the rust resistant oil on the self colored rigging items surface.
Hope you have known the common surface finishing types and understood the differences between them. Let us know if you need any of the rigging hardware products we offer, we can take your business to the next level.
If you want to get more useful knowledge about the surface finish of rigging items, you can contact us by email at [email protected]. We will be glad to share with you more useful information.