Tag: chain inspection

Hoist Pre-Operational Safety Inspection Part 7: Chain Inspection

Hoist Pre-Operational Safety Inspection Part 7: Chain Inspection

This article is Part 7 of a 7-part blog series that will cover what operators should consider when performing a pre-operational hoist safety inspection. Today, we’ll discuss chain inspection.

hoist chain inspection

The final step in our pre-operational hoist safety inspection should be to check the hoist’s chain.

Clean the chain, if required, before inspection.

If the chain is dirty, it may be difficult to inspect. Therefore, it is important to make sure the chain is clean so you can see any damage. Inspect as much chain as you can. On hoists hung from overhead trolleys and beams, you will not be able to inspect the entire length of chain. Checking the entire length of chain will be part of a Periodic Inspection.

When conducting the hoist chain inspection, you should look for:

  • Inner link wear, gouges, nicks and twists: Inner link wear is difficult to see without moving links and is covered in detail during the Periodic Inspection. However, if something looks wrong, have someone check the chain in more detail.
  • Bent or broken links
  • Chemical damage or corrosion
  • Stretch: Hoist chain does not stretch like lifting chain. As I explained in a recent blog post on rigging chain, it can be difficult to determine if chain is stretched without measuring it. Full measurements are completed during the Periodic Inspection. However, if something looks wrong or out of proportion, take the time to measure the links. Chain sizes vary from hoist to hoist so you will need to refer to the product’s O&M manual to verify chain measurements.

Finally, check for proper lubrication.

Lubrication is important to extend the life of the chain and the hoist. It helps wear and helps the chain articulate properly. After you clean it for the inspection, make sure it is properly lubricated.
Here are some extreme examples of chain damage. Often wear will not be this apparent.

Important note to the stretched links image:
Hoist chain is not designed to stretch, whereas rigging chain is designed to stretch.

Hoist Training
If you see anything of concern, take the hoist out of service and bring it to the attention of a trained hoist inspector for further evaluation.

Additional Resources:
Learn more about hoist inspection and maintenance

Peter Cooke

Peter Cooke is a Training Manager specializing in Rigging & Load Securement for Columbus McKinnon Corporation.

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

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

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

Additional Resources:

Peter Cooke

Peter Cooke is a Training Manager specializing in Rigging & Load Securement for Columbus McKinnon Corporation.

In-Depth Alloy Chain Sling Inspection Part 1: Twisting and Bending

In-Depth Alloy Chain Sling Inspection Part 1: Twisting and Bending

twisting and bending

Twisted and Bent Chain
twisting and bending
D/d is the ratio between the curvature taken by the sling ID and the diameter of the component chain D.

 

 

 

 

 

 

 

 

 

This article is Part 1 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 the effect of twisting and bending.

Consider that chain is evaluated by applying loads in a pure tensile link end-to-link-end fashion and rated accordingly. Rigging chain around edges or corners alters the normal loading pattern significantly. A lack of proper padding or consideration of the D/d ratio (see above) for chain can result in twisted and bent links. Once a chain is twisted or bent it will alter inner link stresses which can result in failure. For this reason, all chain containing twisted or bent links must be removed from service immediately.

National Association of Chain Manufacturers (NACM), representing domestic manufacturers of welded and weldless chain since 1933, has conducted D/d testing on alloy chain. As a result of this testing, the NACM came out with the chart below which shows reductions in working load limits based on D/d ratio of alloy chain rigged around an edge or a corner. Consult the manufacturer for any D/d below 2. The latest revision ASME B30.9 2014 released for sale this month has adopted this chart into the new standard.

twisting and bending
Using proper sling protection, following the D/d capacity reductions and exercising proper rigging practices will eliminate damage to your alloy chain slings.

To learn more, view our Chain Sling Inspection Safety Webinar.
Want to get trained? Check out our Qualified Rigger 3 day Workshop.

Peter Cooke

Peter Cooke is a Training Manager specializing in Rigging & Load Securement for Columbus McKinnon Corporation.

Does Welding Spatter Warrant the Replacement of a Chain?

Does Welding Spatter Warrant the Replacement of a Chain?

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Joe, a salesperson for a CMCO distributor and recent safety webinar attendee, asks: “Does welding spatter warrant the replacement of a chain?”

Peter Cooke, CMCO Training Manager and Safety Webinar presenter, answers:
Yes, weld spatter does warrant chain replacement. Weld spatter should be considered as heat damage. Because hoist chain is heat treated, any heat 410 degrees F and up could have an effect on the chain’s integrity. Weld splatter is molten metal at temperatures above 2,000 degrees. When it comes into contact with the chain, weld spatter adversely affects the heat treat properties of the link or links and the chain must be replaced.

To learn more about hoist chain inspection & lubrication, we encourage you watch the following safety webinars:

Hoist Chain Inspection and Maintenance
Hoist Chain Lubrication: Why is it so important?

Gisela Clark

Gisela Clark is an eMarketing Specialist for Columbus McKinnon Corporation.