FORGED STEEL WIRE ROPE CLIPS VS. MALLEABLE CAST IRON CLIPS
What’s the difference between wire rope clips? Guest blogger Danny Bishop, Director of Training for Crosby stopped by Hercules SLR is here to share some information about the difference between malleable cast iron and forged U-Bolt clips.
Read on to discover his expert tips for rigging with U-Bolts.
U-Bolt style wire rope clips are one of the most commonly used accessories in the world of rigging. They can be found in many lifting and non-lifting applications.
Some common applications include winch lines, crane hoist lines, suspension cables, barrier cables, guy wires and many more applications. However, it is critical that the user know there are differences between a forged steel wire rope clip and a malleable cast iron clip.
The forged steel wire rope clip consists of a U-Bolt, two nuts and a forged steel base, which is sometimes called the saddle.
The malleable cast iron U-Bolt style wire rope clip consists of the same components as just mentioned except the clip base is NOT forged steel. In fact, it is a malleable cast iron, and that can make a big difference in the performance and reliability of the clip. The malleable cast iron base does not have the desirable material properties of steel, or the beneficial grain structure that a forged base provides. Although, malleable cast iron products have their place in industry, it is not the manufacturing process of choice for wire rope clip bases. This is especially true if the wire rope clip could be used in a critical application.
Notice that some standards do not allow the use of malleable cast iron clips in critical applications. One example would be ASME B30.5 which states that “Wire Rope Clips shall be drop-forged steel of single saddle (U-Bolt) or double saddle clip. Malleable cast iron clips shall not be used. “ASME B30.26 also states: “Saddles shall be forged steel.”
Additionally, shortcuts in the production process of the bases may also indicate there could be other shortcomings of the product. In some recent testing of malleable cast iron clips, it was found that U-Bolts fractured prior to achieving the recommended forged U-Bolt Clip torque, on 2/3 of the assemblies tested. (See picture of test mentioned).
- Malleable Cast Iron Clip bases are significantly different from forged bases in size, shape and appearance. See figure 1 to compare a Crosby forged clip base and a Malleable Cast Iron clip, both for ½” wire rope.
- Malleable Cast Iron bases are inconsistent in strength, and can have hidden defects.
- Malleable Cast Iron clips should not be used for critical applications.
Note the significant difference in size, shape and appearance even though both are 1/2″ diameter for wire rope. Also, the Crosby clip exceeds ASME B30.26 marking requirements. No readable markings were found on the malleable cast iron clip.