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. 


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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

Crane & Hoisting System: the dangers of side pulling

cm hoisting system at hercules slr

Crane & Hoisting System Safety: guest post from CM Canada

Overhead lifting operations, like a hoisting system or cranes, are necessary in workplaces around the globe. The ability to lift and move material safely is critical to the success of many businesses. Failure to follow safe lifting practices can lead to serious personal injury and cause damage to equipment and facilities.hoisting-system

While there are many aspects to safe lifting procedures, one critical issue to discuss is “side pulling” and how to avoid it. Today, Hercules SLR welcomes guest blogger CM Canada to discuss the dangers of side pulling when using a crane or hoist.

Crane & Hoisting System Safety: overhead hoists are designed to raise loads vertically

Accordingly, the load being lifted must be centered under the hoist (Figure 1). Side pulling (Figure 2) occurs when you attempt to lift any load that is not located directly under the hoist. Another form of side pulling occurs when a crane operator attempts to use the trolley drives or bridge to apply force to move an object horizontally when the load isn’t first fully suspended on the hoist – it should be clear of the floor or other support. Regardless of how a side pull is applied, unintended, damaging and potentially dangerous results can occur. Side pulling a hoist or crane, in most cases, results in a violation of OSHA regulations, and numerous industry standards – check your provincial regulations for specific standards.

hoisting-system-cm-bandit
CM Bandit Hoist

ASME B30.16, a safety standard for overhead hoists (underhung) states that:

Hoists shall not be operated unless the hoist unit is centered over the load, except when authorized by a qualified person who has determined that the components of the hoist and its mounting will    not be overstressed. Should it be necessary to pick a load that is not centered under the hoist unit, precautions should be taken to control the swing of the load when it is picked clear of its support.

Crane & Hoisting System Safety: what are the dangers of side pulling?

  • As the load is lifted free of the floor or other support it will attempt to center itself under the hoist, causing the load to rapidly swing in a horizontal arc (Figure 3). This pendulum effect can cause serious injury to personnel or damage to other equipment in the area.hoisting-system
  • The wire rope or load chain can be forced out of the grooving or pockets on the hoist drum or lift wheel. This can damage the chain/rope, and may also cause damage to drums, sheaves, and other components. In the best case scenario, this can lead to costly repairs and downtime. More importantly, it could cause the chain or wire rope to break and the load to drop, putting equipment, facilities, and personnel at serious risk.
  • Side pulling at an angle that is not in line with the length of the bridge or monorail (Figure 4) could cause the trolley hoist to tip, making the trolley inoperable. In the worst case, the trolley hoist could actually be pulled off of the beam. This side pull condition also puts stresses on the beam itself and could cause the beam to skew (Figure 5).
  • Side pulling is not considered “normal operation” of the hoist and therefore may void the manufacturer’s warranty.
  • Attempting to lift a load that is located beyond the end of a bridge beam or monorail (Figure 6) could damage the safety stops at the end of the beam. In rare cases, this has caused the trolley hoist to fall off the end of the beam.

rigging equipment

 

 

 

 

 

The number of inquiries professional riggers receive regarding side pulling amaze me. These are sometimes phrased like “what is the maximum angle of side pull that is permissible with your hoist?” Customers may also make a statement such as “The distance from my bridge beam to the floor is only 20’ but I need a few feet of additional wire rope on the hoist so I can pull materials out of the adjoining bay.”

These are the GOOD situations, where at least the potential for side loading has been made known and it can be properly addressed. What worries me are the situations where these circumstances may exist but are not made known to the hoist/crane manufacturer or crane service provider.

Fact: Side pulling is one of the most common and most dangerous mistakes with overhead cranes. 

Crane & Hoisting System Safety: 5 steps to help avoid side pulling hazards

  • Make sure that all new crane and monorail systems are designed and installed by qualified material handling professionals.
  • Have existing overhead lifting equipment and lifting applications reviewed by a qualified person to ensure these systems are properly located to provide full hook coverage (without side pulling) for all locations where materials to be lifted are located.
  • Arrange for hoist and crane operator safety training of all personnel within your organization who may use overhead lifting equipment as well as all managers or supervisors who may direct others to use that equipment.
  • Ask your overhead lifting equipment provider about the availability and functionality of devices such as overlay limit switches, rope guides and others equipment used to detect, prevent or reduce the damaging effects of unintended side pulling.
  • Consider using an adjustable lifting beam and counterweight to allow an off-center load to be lifted without creating side-pull on the hoist.

Reproduced with Permission from Columbus McKinnon. Original article here: http://blog.cmworks.com/crane-hoist-safety-dangers-side-pulling/ 

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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.