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