In-Depth Alloy Chain Sling Inspection Part 2: Nicks and Gouges

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by  on April 10, 2015

This article is Part 2 of a 5-part blog series that will cover what professional riggers should consider when performing an in-depth alloy chain sling inspection. Today, we’ll discuss nicks and gouges.

nicks and gouges

When chain is used to lift, pull or secure materials, the outside surface of the links can come in contact with foreign objects that can cause damage. Nicks and gouges frequently occur on the sides of a chain link, which are under compressive stress, reducing their potentially harmful effects.

The unique geometry of a chain link tends to protect tensile stress areas against damage from external causes. Figure 1 shows that these tensile stress areas are on the outside of the link body at the link ends where they are shielded against most damage by the presence of interconnected links.

Tensile stress areas are also located on the insides of the straight barrels, but these surfaces are similarly sheltered by their location. However, gouges can cause localized increases in the link stress and can be harmful if they are located in areas of tensile stress, especially if they are perpendicular to the direction of stress. Refer to Figure 1.

nicks and gouges

Figure 2 shows nicks of varying degrees of severity. Reading clockwise, at three o’clock there is a longitudinal mark in a compressive stress area. Since it is longitudinal and located in a compressive stress area, its effect is mitigated, but good workmanship calls for it to be filed out by hand.

At about five o’clock there is a deep transverse nick in an area of high shear stress. A similar nick is located at six o’clock in the zone of maximum tensile stress. Both of these nicks can create a potentially dangerous escalation of the local stress and must be filed out with careful attention to not damage other parts of the chain link or chain. A nick that was located at eight o’clock has been filed out properly. Although the final cross section is smaller, the link is stronger because the stress riser effect of the notch has been removed. The remaining cross section can now be evaluated for acceptablity by measuring it and applying the criterion for worn chain. See the “Wear Allowances Table” below. 

nicks and gouges

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{ 5 comments… read them below or add one }

Peter Cooke Peter Cooke September 9, 2016 at 6:46 pm

Hi Jeff,
Yes, it is considered a repair. Grinders are not recommended since they can generate high heat.
Peter

Jeff September 8, 2016 at 2:11 pm

When you file out nicks and gouges, is this considered a ‘repair’?
Can you use an electric grinder to remove the same?

Peter Cooke Peter Cooke April 7, 2016 at 6:50 pm

Hello Slade,
Our apologies for the very late response. All Columbus McKinnon chain is marked with the CM logo. The only difference between them would be the grade. Here is another article that you might find helpful: http://blog.cmworks.com/understanding-the-difference-between-chain-grades-and-how-theyre-used/
Thanks for reaching out to us,
Peter

Slade Livermore March 24, 2016 at 4:02 pm

How would I identify whether or not I am using Columbus McKinnon chain or not? Is there a marking on the links and if so what is the marking?

Alice Spencer April 27, 2015 at 6:44 pm

A very informative article. Thank you for sharing this with us. It will definitely help me with my project.

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