Author: Peter Cooke

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

Understanding Chain Slings: Why Do Only 3 of 4 Chain Legs Take the Load?

Understanding Chain Slings: Why Do Only 3 of 4 Chain Legs Take the Load?

Randy, an Instrument Technician in the energy industry and recent safety webinar attendee, asks:

“Why do only 3 of 4 chain sling legs take the load?”

Peter Cooke, Columbus McKinnon Training Manager and Safety Webinar Presenter, answers:

understanding chain slings
When using a chain to build a sling, tolerances for chain can make the legs slightly longer or shorter than one another. Because of this, the National Association of Chain Manufacturers (NACM) agreed to only count 3 of the 4 legs of a quad sling to be rated the same. When you first lift the load off the ground the legs that are under tension will stay under tension, so it is important for the rigger to visually see how many legs are loaded before lifting the load off the ground.

To do this, tension up the legs, but do not let the load leave the ground. Safely approach the sling being sure to stay out of the path of tension. You can then quickly check the legs by shacking them slightly. Although you may find all four legs are taking the load, only three are used for calculating the max working load limit of the sling.

It is important to always check the manufacturer’s load charts and safety information prior to making any lift. You must be qualified to lift the load you are rigging.

Want to learn more?

View our Safety Webinar on How to Size Your Chain Slings.
View our blogs on chain sling inspection.

Peter Cooke

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

In-Depth Alloy Chain Sling Inspection Part 5: OSHA Chain Sling Inspection

In-Depth Alloy Chain Sling Inspection Part 5: OSHA Chain Sling Inspection

This article is Part 5 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 OSHA chain sling inspection regulations and guidelines.

Since first published on July 27, 1975, the OSHA Chain Sling Inspection section has undergone very few changes. These regulations have and continue to serve as a comprehensive guide for those responsible for chain sling inspection.

Chain SlingSpecifically, the applicable sections of the Code of Federal Regulations (29 CFR 1910.184) include:

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.

1910.184(e) Alloy steel chain slings

1910.184 (e)(1) Sling identification
Alloy steel chain slings shall have permanently affixed durable identification stating size, grade, rated capacity, and reach.

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.

1910.184(e)(3) Inspections

  • 1910.184(e)(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)(ii)
    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. However, the minimum 12-month interval inspections required under (e) call for thorough inspection and written records. It is this thorough type of inspection that the procedures recommended in our Rigging Catalog and CMCO Training Classes are designed to satisfy.

Of course, the fundamentals are equally applicable to the more cursory daily inspections made by riggers, users or inspectors (individuals deemed a “competent person”) and will enable them to fulfill their responsibility efficiently.

For more information:

 

Peter Cooke

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

In-Depth Alloy Chain Sling Inspection Part 4: Stretch and Chain Elongation

In-Depth Alloy Chain Sling Inspection Part 4: Stretch and Chain Elongation

This article is Part 4 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 stretch and chain elongation.

Stretched Links
Stretched Links

A visual link-by-link inspection is the best way to detect dangerously stretched alloy chain links. Reach should also 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 that 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. Overloading must be prevented before it happens by selection of the proper type and size of slings. Again, any amount of stretch is overloading and the chain 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.

Additional Resources:

In-Depth Alloy Chain Sling Inspection Part 1: Twisting & Bending
In-Depth Alloy Chain Sling Inspection Part 2: Nicks and Gouges
In-Depth Alloy Chain Sling Inspection Part 3: Wear & Corrosion

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.

In-Depth Alloy Chain Sling Inspection Part 3: Wear and Corrosion

In-Depth Alloy Chain Sling Inspection Part 3: Wear and Corrosion

This article is Part 3 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 chain wear and corrosion.

chain wear
Figure 1: Inspection for interlink wear can be easily detected by collapsing the chain.

When used in rigorous material handling applications, chain can easily become worn or corroded. 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.

Figure 1 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 chart below 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 wear

Stay tuned for our next part in this series where we’ll talk about Chain Inspection.

Additional Resources:

In-Depth Alloy Chain Sling Inspection Part 1: Twisting & Bending
In-Depth Alloy Chain Sling Inspection Part 2: Nicks and Gouges

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.

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.

A Chain Sling Question from the Mining Industry

A Chain Sling Question from the Mining Industry

Chain Inspection photoHere is a question from Adam, a mobile crane operator working in the mining industry, who regards proper rigging equipment and practices as a major safety priority:

“We have a 1-inch GR80 chain sling, 30 feet in length that is around ten years old and in good condition, although there is inner link wear throughout the sling at its bearing points. The narrowest measurement in link diameter at any point was .945″, which is well away from removal criteria. No components in the sling show any evidence of a stretch condition, and the sling has not been subjected to overload to the best of our knowledge, though I cannot guarantee that.

“The reach of the sling is approximately four inches longer than its tag indicates. According to my calculations, this stretch is due to the contact wear in each link. The chain moves freely and there is no binding or restriction of movement. Is this legitimate? If so, does the tag need to be replaced or modified to indicate its current length? Our inspections have always been completed by a company assigned employee.”

Response from Peter Cooke, training manager:

Thank you for reaching out to us. For your reference, I have included a section on alloy rigging chain inspection from our Columbus McKinnon rigging catalog here. Be sure to do a link-by-link inspection and follow the rejection criteria from OSHA 1910.184 and ASME B30.9. Be sure there are no stretched links. Reference the “Allowable Chain Wear Allowance tables” from the manufacturer and ASME B30.9.

Not knowing your exact configuration, I will use a standard DOS 1-inch grade 80 x 30’ reach sling as an example. If we just isolated the chain (taking out the master link, coupling links and hooks) you have approximately 106 links of chain. If you determined the minimum thickness to be 0.945” at the bearing points, that is approx. 0.055” of wear from the nominal dimension. 1” grade 80 chain has a pitch length of approx. 3.07” (dimension from the top inner link radius to the lower inner link radius) Let’s assume that wear occurred at both ends of the chain link. The pitch length would increase by 0.11”. Over the entire chain length you could see an increase in reach of approx. 11.66” (0.11” x 106 = 11.66”)

As long as there are no stretched links or deformation this would be acceptable. There is no rejection criteria for reach other than stretch. Wear is not stretch.

There is also no statement in 1910.184 and ASME B30.9 to replace the tag in this event with the correct reach.

A good practice would be to retag the sling with the current reach. The new tag would be considered a repair so your company’s name or initials would have to be on the tag. A load test would not be required. Lastly, lubricating the chain is an excellent way to minimize wear.

Peter Cooke

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

Can Lever Tools be Used to Adjust Slings?

Can Lever Tools be Used to Adjust Slings?

Q & A chat Richard, a salesperson for a CMCO distributor and recent safety webinar attendee, asks: 

“Is it acceptable to use lever tools to shorten or lengthen slings? Are there any concerns of locking up the lever tool brake?”

 

Peter Cooke, CMCO Training Manager and Safety Webinar presenter, answers:
Your first step is to go to the manufacturer to make sure the lever tool is designed for hoisting.  If the lever tool can be used for hoisting, then you need to pre-plan the lift. To do this, you need to know the share of load and go through the calculations to determine the center of gravity. From there you will be able to size your tensions and choose the right lever tool for the application.

To learn more about rigging using lever tools, we suggest you watch our safety webinar on this topic here.

Locking Up a Lever Tool Brake
In general, lever tools are defined by the type of brake they use:

  • Weston-Type, that utilizes friction discs and a ratchet and pawl
  • Ratchet & Pawl, that is a more archaic design similar to an old car jack.

To avoid locking up the hoist, we recommend a lever tool with a Weston-type brake for hoisting applications. These tools rely on friction and provide a smoother operation. To use the Weston-type brake tool you will need to release the load on the brake before removing the load. When the load is a few inches from the ground, switch the hoist to unload and release the tension by operating the handle. This will prevent the hoist from locking. If this is not an option, then you will need to use a ratchet-and-pawl-type lever tool to prevent the hoist from locking when the tension is removed.

Want to learn more about properly rigging and lifting a load? Watch our August Safety Webinar entitled “Determining the Center of Gravity.”

Peter Cooke

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

Missing Chain Sling ID Tags: Who Is To Blame?

Missing Chain Sling ID Tags: Who Is To Blame?

missing chain sling ID tagsJason asks:

Who is responsible for putting tags on chain slings?  Can I retag my chain slings with missing tags?  Do I have to load test a sling after I retag it?

Peter answers:

It is the sling manufacturer’s responsibility.  The sling manufacturer is a person or company assembling or fabricating sling components into their final form.  The sling manufacturer and the manufacturer of the sling materials may or may not be identical.  An end user who buys components and assembles them mechanically is the sling manufacturer. If the user does not know who the sling manufacturer is because the old tag fell off and went missing, then a decision needs to be made.  It is the user’s or rigger’s responsibility to maintain the tag and be sure it remains legible.  A rigger can not use a sling without a tag or when a tag is illegible or missing information.

Replacing missing chain sling ID tags becomes a question of competency.

Can the user properly inspect and retag the sling? For retagging, the user would need to start his own serial number for documentation purposes.  In doing so, this user would become the “sling manufacturer.” This can only be done if the user is properly trained and deemed competent.  Per OSHA,  a person who tags a sling must be a competent person designated by the employer.  ASME B30.9 states: replacement of the sling identification shall be considered a repair.  Slings shall be repaired only by the sling manufacturer or a qualified person. A repair shall be marked to identify the repairing agency. To be considered competent and or qualified, the user should have some inspection experience and complete a rigging gear inspection course from a reputable training organization.

If the user feels they are not competent to properly inspect and retag the sling, they would need to send the sling out to a rigging house with a competent person for inspection and retagging.  That rigging house now becomes the “sling manufacturer.”  Tags must have information per OSHA 1910.184(e) Alloy steel chain slings.  I have noted the key points below referencing both OSHA and ASME standards:

missing chain sling ID tags

OSHA 1910.184(e)(1) Sling Identification
Alloy steel chain slings shall have permanently affixed durable identification stating size, grade, rated capacity, and reach.

ASME B30.9:  SECTION 9-1.7: Sling Identification
9-1.7.1 Identification Requirements

Each sling shall be marked to show:
(a) name or trademark of the manufacturer
(b) grade
(c) nominal chain size
(d) number of legs
(e) rated loads for the type(s) of hitch(es) used and the angle upon which it is based
(f) length (reach).

A load test is not required if a sling is made up of individual load tested components from the component manufacturer. If the sling is always found in acceptable condition per ASME B30.9, OSHA 1910.184 and manufacturers’ recommendations, then the sling can remain in service without ever needing another load test performed.

Interested in getting trained? Learn more about our upcoming training classes.

Peter Cooke

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

Hook Tip Loading is Risky Business

Hook Tip Loading is Risky Business

Q-&-A-chat_15A

 

 

 

 

Hook tip loading is a common problem. While reading through one of our catalogs, Brian ran across our instructions and asked the following question,  “What does it mean to never insert a hook tip?”

Peter answers:

Hooks typically do not fit into an eyebolt or they don’t seat properly in the saddle of the hook.  This can cause side loading and weaken the strength of the eyebolt.  Inserting a hook directly into the eye of the bolt often results in “Tip Loading.”   A “tip load” would be any load on a hook that is not entirely or wholly seated in the saddle of the hook.  Tip loading subjects the hook to an overload and is never acceptable. It is recommended that a shackle be used to connect a hook to any eyebolt to prevent any unnecessary stress. Please see the below illustration for the correct procedure.

Never insert a hook tip_rev1 copy

For additional reference, please review the ASME B30.10 Hooks  and B30.26 Rigging Hardware safety.

Peter Cooke

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