In the past (pre 19th century), most heavy haulage and lifting needs were met by bulky chains or big ropes made of fiber. In the early 1830’s, a mine in Germany dropped a mine conveyance full of ore to the bottom of their mine and it was found that the heavy chains they were using to haul the conveyance to the surface suffered from work hardening and became severely brittle, leading to its failure.

As time progressed, other nations and people began to experiment with the fabrication of wire rope and, initially, each of them were essentially drawing hot steel through some dyes to create wires which were then laid helically together to form the wire rope. The type of steel that was readily available at the time was the same steel used to create ploughs for agriculture; thus the “Plough Steel” designation was used to denote what grade of steel was used to fabricate the rope.

Improvements were made to the ingredients of Plough Steel that allowed for a higher tensile strength of the wire rope. This new grade was aptly named, “Improved Plough Steel” or I.P.S. for short. Improved plough steel became the de facto steel to be used until it was once again improved upon, to the point where it is actually difficult to find Plough Steel grade wire rope in inventory at a sling shop.

Speaking of improvements made to the already Improved Plough Steel, once the recipe was perfected and it was found that wire rope could be made to have some extra strength. What did the powers that be name this new and improved wire rope…You guessed it, “Extra Improved Plough Steel.” EIPS offers approximately 10-15% increases in tensile strength over the old IPS depending on diameter. The higher tensile strength improves the minimum breaking strength of the wire rope. This, of course, will change the breaking strengths of the rigging mines and other industrial uses. This makes it important to know what type of wire rope your rigging is constructed from. If for example, a worker is referencing a sling chart for minimum breaking strength of a sling they should:

• a) check to see if the chart is referencing IPS  or EIPS 
• b) know if his sling is IPS or EIPS.
• Referencing an EIPS chart while lifting with a IPS sling could result in the sling being overloaded and breaking.

Currently, most rigging shops have transitioned to EIPS or are in the process of doing so. EIPS wire rope should be the standard in a modern day rigging shop and used for rigging such as wire rope slings, winch lines, and wire rope assemblies.

                                                                                  EIPS Sling Chart

Have you wondered why rigging experts always suggest a sling that has a significantly higher breaking strength than the actual weight of the load you are lifting? The manufacturers know that the rigging used in overhead applications need to have room for error. This is known as the Safety Factor.

Northern Strands manufactures wire rope slings rated up to 36,000 lbs and sells round synthetic slings that are rated up to 140,000 lb capacity. This capacity is the Working Load Limit of the sling, which is the maximum amount of weight or force that the sling's user is allowed to put on the sling. Note: These slings do not break at the working load limit. These slings are designed with a safety factor of 5:1. This means that 5 times as much force as the working load limit has to be applied to the sling before it potentially fails. This means the wire rope slings have a Breaking Strength of up to 180,000 lbs and the round synthetic slings can withhold up to 700,000 lbs.

Why are these capacities reduced by such a drastic degree?

Among others, here are 3 good reasons:

1. Shock Loading - Unexpected drops where the load can accelerate and then must be 'caught' by the slings.
2. Wear - Working load limits are based on slings in brand new condition and a safety factor can help account for normal wear and tear until it is deemed unfit for further use.
3. Uneven loading - Slings are made up of either wires or fibers that must all share the weight of the load evenly. If any situation arises where the sling is bent or wrapped around an object, there is potential that some of the wires or fibers will be taking on a greater share of the load than others.

Visit Northern Strands website to use the sling tension calculator. The Northern Strands Sling Calculator has been designed to assist you in selecting slings with enough load carrying capacity for your lifting applications. It is your responsibility to assure that the slings you use are appropriate for your application.  http://www.northernstrands.com/sling-calculator.aspx

To inquire about Rigging and Safety Factors, contact:

Northern Strands @ 306-242-7073

or Email info@northernstrands.com

Recently the company, "Concept Group" had round slings made for them by Northern Strands.  Soon after, Concept Group sent an email praising Northern Strands service and knowledge .

Here is the portion of that email discussing our service.

“One of our guys was in earlier today to purchase 20 slings from you folks.  By the way he says you were very knowledgeable and fantastic to work/deal with.”

Thank you Concept Group for your high praise of our knowledgeable employees!  Northern Strands Warehouse proudly employees some of the most technically trained and knowledgeable employees in the industry.

Northern Strands Warehouse/Rigging Division

Our Capabilities:
• Northern Strands has Saskatchewan’s largest inventory of
  wire rope available from 1/16” to 2” in standard sizes and
  5.5mm to 26mm in metric sizes.
• Large selection of rigging products.
• Distributor for some of the largest world class
  manufacturers in our industry including The Crosby
  Group, Gunnebo Johnson, Thern, Unitex and Vitali.
• Crane rope inspections.
• Assistance in the development of rigging and lifting
  plans for your job.
• Technically trained sales staff. We have the answers to
  your questions.
• Certificate of compliance for rigging products. Safe and
  approved for every job.
• Custom built products. i.e. material baskets, chain and
  wire rope slings, etc.
• Vertical and horizontal test bed services.

Northern Strands is proudly Saskatoon, Saskatchewan owned and operated.

Northern Strands Rigging Division is a full-service facility operating out of Saskatoon and Regina with the ability to fabricate custom chain and wire rope slings up to 1-1/2”. We have a vast inventory of synthetic lifting slings, chain hoists, lever hoists, shackles, trolleys, winches ,tuggers , and other general rigging hardware. Our network of suppliers and in-house expertise is leveraged for the benefit of our customers.

Capabilities:

• Northern Strands has Saskatchewan’s largest inventory of
  wire rope available from 1/16” to 2” in standard sizes and
  5.5mm to 26mm in metric sizes.
• Large selection of rigging products.
• Distributor for some of the largest world class
  manufacturers in our industry including The Crosby
  Group, Gunnebo Johnson, Thern, Unitex and Vitali.
• Crane rope inspections.
• Assistance in the development of rigging and lifting
  plans for your job.
• Technically trained sales staff. We have the answers to
  your questions.
• Certificate of compliance for rigging products. Safe and
  approved for every job.
• Custom built products. i.e. material baskets, chain and
  wire rope slings, etc.
• Vertical and horizontal test bed services.

Here is the link to our Rigging webpage on the Northern Strands website:

http://www.northernstrands.com/wire-rope-rigging.aspx 

Northern Strands is proudly Saskatoon, Saskatchewan owned and operated.