Chain Sling Inspection | 5 Steps for In-Depth Inspection from CM

chain by columbus mckinnon

In-Depth Alloy Chain Sling Inspection | 5 Steps

How should you conduct an in-depth alloy chain sling inspection? Columbus McKinnon is here on the Hercules SLR blog to share what a professional rigger needs to know when they perform an alloy chain sling inspection. 

This blog will cover: 

  • Twists and bends in your chain sling,
  • Nick, cuts & gouges in the chain links 
  • Wear and corrosion 
  • Chain stretch and elongation
  • OSHA guidelines for chain sling inspection 

Read on to become a chain sling inspection pro. 

CHAIN SLING INSPECTION PART 1: TWISTING & 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.

Since 1933, the National Association of Chain Manufacturers represents domestic manufacturers of welded and weldless chain and have 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.  ASME B30.9 2014 has adopted this chart into the new standard.

columbus mckinnon chain sling rated capacities

 

 

 

 

 

 

CHAIN SLING INSPECTION PART 2: NICKS & GOUGESchain sling link tensile and compression stress pattern

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.

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-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 acceptability by measuring it and applying the criterion for worn chain. See the “Wear Allowances Table” below. 

chain sling wear allowances table

 

 

 

 

 

 

 

 

CHAIN SLING INSPECTION PART 3: WEAR & CORROSION

When used in rigorous material handling applications, chain becomes worn or corroded easily. It is important to inspect chain for defects on a regular basis to avoid an unsafe lifting condition or even operator injury. When corrosion and wear occur, it results in a reduction of link cross-section which can lead to decreased strength of the chain.

Corrosion can occur anywhere chain comes in contact with harsh chemicals, water or when it is used in tough environments.

Wear can occur in any portion of a link that is subject to contact with another surface.

The natural shape of chain confines wear, for the most part, to only two areas. These are, in order of importance, (a) at the bearing points of interlink contact, and (b) on the outsides of the straight side barrels that may be scraped from dragging chains along hard surfaces or out from under loads.

collapsed chain link example
Figure 2: Inspection for interlink wear can easily be detected be collapsing the chain.

Figure 2 illustrates the condition of interlink wear and shows how to inspect for it. Notice how easily such  wear can be detected by collapsing the chain to separate each link from its neighbors. An operator or inspector can also check for corrosion using the same method.

When chain wear or corrosion is observed, the next step is to determine how severe the damage is and if the chain can still be safely used.

General surface corrosion can be removed by cleaning and oiling the chain. If pitting is observed after cleaning and oiling, remove from service. Next, the operator should take a caliper measurement across the worn section of chain and compare it to the minimum allowable dimension for that chain.

See the Wear Allowances chart above for minimum section dimensions or chain wear allowances for Grade 80 and 100 Chain. If the chain does not meet these minimum dimensions, it should be removed from service and replaced.

 

CHAIN SLING INSPECTION PART 4: STRETCH & CHAIN ELONGATION

A visual link-by-link inspection is the best way to detect dangerously stretched alloy chain links.

Reach should be measured from the upper bearing point on the master link to the bearing point on the lower hook. The smallest sign of binding or loss of clearance at the juncture points of a link indicates a collapse in the links’ sides due to stretch. Any amount of stretch indicates overloading, and the chain should be removed from service.

Note: A significant degree of stretch in a few individual links may be hidden by the apparent acceptable length gauge of the overall chain. This highlights the importance of link-by-link inspection.

Alloy steel sling chain typically exhibits well over 20% elongation before rupture. The combination of elongation and high strength provides energy absorption capacity.

However, high elongation or stretch, by itself, is not an adequate indicator of shock resistance or general chain quality and should not be relied upon by riggers to provide advance warning of serious overloading and impending failure.

Prevent overloading the chain sling by selecting the right type and size of sling. Again, any amount of stretch means the sling’s been overloaded and it should be removed from service.

There is no short-cut method that will disclose all types of chain damage. Safety can only be achieved through proper inspection procedures. There is no adequate substitute for careful link-by-link scrutiny.

CHAIN SLING INSPECTION PART 5: OSHA CHAIN SLING INSPECTION

OSHA Chain Sling Inspection standards have gone through minimal changes since they were published on July 27, 1975. These regulations serve as a guide for rigger’s and other competent personnel that will inspect chain slings. 

Applicable sections of the Code of Federal Regulations (29 CFR 1910.184) include:

CHAIN SLING INSPECTION | 1910.184(d) Inspections

Each day before being used, the sling and all fastenings and attachments shall be inspected for damage or defects by a competent person designated by the employer. Additional inspections shall be performed during sling use, where service conditions warrant. Damaged or defective slings shall be immediately removed from service.

CHAIN SLING INSPECTION | 1910.184(e) Alloy Chain Slings

CHAIN SLING INSPECTION: 1910.184(e)(1) Sling Identification

Alloy steel chain slings shall have permanently affixed durable identification stating size, grade, rated capacity and reach.

CHAIN SLING INSPECTION: 1910.184(e)(2) Attachments

  • 1910.184(e)(2)(I)

Hooks, rings, oblong links, pear shaped links, welded or mechanical coupling links or other attachments shall have a rated capacity at least equal to that of the alloy steel chain with which they are used or the sling shall not be used in excess of the rated capacity of the weakest component.

  • 1910.184(e)(2)(ii)

Makeshift links or fasteners formed from bolts or rods, or other such attachments, shall not be used.

CHAIN SLING INSPECTION: 1910.184(e)(3) Inspections

  • 1910.184(3)(I)

In addition to the inspection required by paragraph (d) of this section, a thorough periodic inspection of alloy steel chain slings in use shall be made on a regular basis, to be determined on the basis of (A) frequency of sling use; (B) severity of service conditions; (C) nature of lifts being made; and (D) experience gained on the service life of slings used in similar circumstances. Such inspections shall in no event be at intervals greater than once every 12 months.

  • 1910.184(e)(3)(iii)

The employer shall make and maintain a record of the most recent month in which each alloy steel chain sling was thoroughly inspected, and shall make such record available for examination.

  • 1910.184(e)(3)(iii)

The thorough inspection of alloy steel chain slings shall be performed by a competent person designated by the employer, and shall include a thorough inspection for wear, defective welds, deformation and increase in length. Where such defects or deterioration are present, the sling shall be immediately removed from service.

Please note that while the requirements under (d) for daily inspections are not explicit as to scope or maintenance of records, it is possible that individual OSHA inspectors may have different views on conformity—The minimum 12-month interval inspections required under (e) call for thorough inspection and written records.

To ensure you remain compliant with chain sling inspection in your area, be sure to check both manufacturer and provincial standards. 


FIND MORE CHAIN SLING INSPECTION READING ON OUR BLOG:

WELCOME TO HAMILTON, ONTARIO: MEET RIGGER JIM CASE

RIGGING TIPS: AVOID COMMON WIRE ROPE DAMAGE

WIRE ROPE: A MANUFACTURING & TRANSPORTATION PIONEER


NEED A LIFT? HERCULES SLR PROVIDES CHAIN SLING INSPECTION, REPAIRS & MORE

INFO@HERCULESSLR.COM  1 (877) 461-4876


 FACEBOOK LINKEDIN  TWITTER INSTAGRAM YOUTUBE


Hercules SLR is part of Hercules Group of Companies, with locations and unique businesses coast-to-coast. We provide securing, lifting and rigging services for sectors in Canada and Internationally. Hercules SLR serves the energy, oil & gas, manufacturing, construction, aerospace, infrastructure, utilities, mining and marine industries.

Hercules Group of Companies is comprised of: Hercules SLRHercules Machining & Millwright ServicesSpartan Industrial MarineStellar Industrial Sales and Wire Rope Atlantic.

We have the ability to provide any hoisting solution your business or project will need. Call us today for more information. 1-877-461-4876 or email info@herculesslr.com

Rigging Services: 3 securing tips to lift you anywhere

rigging-services-hercules-slr

Rigging Services

So you’ve got a difficult load to move – whether it’s due to an awkward shape, uneven weight or hard to determine lift points, Hercules SLR rigging services will lift you where you need to be.

We don’t just sell slings at Hercules SLR – we provide inspections, repairs, training and expert advice to keep your projects safe and efficient.

In addition to calculating the load’s weight, there are a few other tips to planning, rigging and executing a successful lift – read on for tips from our expert riggers to secure your hard-to-manage load and accomplish your next lift with ease.

rigging-services-hercules-slr
Crane lifting electric generator

Rigging Services: 3 tips to move an “awkward” load

One

We can’t stress this enough – inspect your equipment! Says rigger Dwayne Fader, Sales Manager at Hercules SLR “Once the equipment is broken, it’s already too late – maintenance and regular inspection is the key to prevention.”

Check the manufacturer instructions or manual for suggested and required inspection times – Unless you want to damage that expensive part, package or material, which costs WAY more over time than simply investing some time and money into inspections.

An informal inspection should be done before each lift, and official inspections should be done according to manufacturer and/or provincial regulations.  

Two

Bigger isn’t always better. Sometimes, you might look at a large object like a vehicle and just think, “well I’ll grab a bigger shackle or sling.” But you’d be surprised at how much support a smaller sling and/or hardware does have.

“Most people are surprised to learn that a small, 2 1/2″ shackle is strong enough to lift a car – bigger shackles are available, but why go bigger when you don’t need to? Often, the smaller piece of equipment will be safer and better suited to the application as it’s meant to support a specific amount of weight.” says Fader.

Using slings which are too big and create bunching are a safety issue, and so is using a shackle which is too big that a sling may slide around in.

Three

Preventative maintenance is a pain, but important. The longer a piece of equipment isn’t inspected or small repairs are ignored, the worse the outcome typically is. A small build-up of issues can eventually lead to large, more expensive repairs. Neglecting preventative maintenance will increase both cost and the risk of injury or death.

Rigging Services: your reading list

Want more? Find more rigging tips and information on our blog – try these:


Hercules SLR is part of the Hercules Group of Companies which offers a unique portfolio of businesses nationally with locations from coast to coast. Our companies provide an extensive coverage of products and services that support the success of a wide range of business sectors across Canada including the energy, oil & gas, manufacturing, construction, aerospace, infrastructure, utilities, oil and gas, mining and marine industries.

Hercules Group of Companies is comprised of: Hercules SLRHercules Machining & Millwright ServicesSpartan Industrial MarineStellar Industrial Sales and Wire Rope Atlantic.

We have the ability to provide any solution your business or project will need. Call us today for more information. 1-877-461-4876. Don’t forget to follow us on FacebookTwitter and LinkedIn for more news and upcoming events.