Tag: NACM

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.

Highlights from the Spring ACRP Meeting

Highlights from the Spring ACRP Meeting

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The Association of Crane and Rigging Professionals (ACRP) recently held its annual meeting in Milwaukee, Wisconsin.

The ACRP is a nonprofit association whose mission is dedicated to improving crane operations and rigging activities in all industries. This is accomplished through educational opportunities to its members and the public. Many ACRP members are heavily involved with other organizations such as ASME, NACM, CMMA to name a few. Columbus McKinnon has board representation and also participates in the educational opportunities.

This year’s meeting theme was Crane Operation Safety.  Topics of discussion included:

  • D/d Ratio of Alloy Sling Chain
  • Turning Pre Cast Loads Safely on the Job Site
  • Design and Safety Criteria for Pad Eyes and Eyebolts
  • ASME Update on P30: ASME P30 is the newest “in development” standard under the ASME umbrella. The intent of this document is to provide end-users with an exceptional guideline that focuses on personnel, equipment and procedures as they relate to repetitive lifts, standard lifts and critical lifts.
  • Boom Assembly / Disassembly
  • How to Find and Calculate the Center of Gravity
  • Responsibilities of Crane Operations
  • How an Overhead Hoist Works (presented by Columbus McKinnon)
  • Critical Lift with Overhead Cranes
  • Derrick Barge Lift
  • Industrial Rollers
  • Overhead Crane Standards and Regulation Update

Each of the topics provided case studies and applications. There was also a tour of the Manitowoc Crane Production Facility. All cranes and attachments manufactured at the Manitowoc facility are rigged and tested in the 20 acre test yard. The machines are tested to ensure the safety, quality and functionality of the delivered product. Currently being tested in the yard was a 2300 metric ton crane. It was the largest capacity crawler ever designed and built by Manitowoc.

ACRP is where Trainers get Trained. Information is openly shared and is provided to members of ACRP for use in their own training programs.

Peter Cooke

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

NACM Position on Tagging of Chain Tie-Downs

NACM Position on Tagging of Chain Tie-Downs

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As provided by the NACM Technical Committee on May 2, 2011

The NACM  (National Association of Chain Manufacturers) has been asked to provide its position on the need to add additional tagging to tie-down assemblies due to some apparent confusion in Canada.

The Canadian National Safety Code for Motor Vehicles released Standard 10 – Cargo Securement (September 2010, effective January 1, 2011). There is no requirement for, or even mention of, additional tagging of chain tie-downs. Instead, the opposite is true. The Standard states that “A chain that is marked by the manufacturer in accordance with the table of Working Load Limits under Part 4 – Section 7 has a working load limit equal to the amount shown for the grade and size.” Section 7 lists the NACM Welded Steel Chain Specifications as the reference document, and lists the grade indicators contained in the NACM specification in the table. Excerpts from this standard are included below.

This is also in agreement with the similar United States Federal Motor Carriers Safety Administration Part 393 Regulations Subpart I, Protection against shifting and falling cargo,  Sections 393.100 through 393.136. There are no requirements for separate tagging of chain tie-down assemblies.

Based on the above and below references, as well as the complete absence of any specification that requires additional tagging, it is the NACM position that additional tagging is not required for chain tie-down assemblies in either Canada or the United States.

 

Canadian National Safety Code for Motor Vehicles, Standard 10: Cargo Securement, September 2010, Effective 1/1/2011

REFERENCE 1

Part 2 – General Provisions, Division 3 – Requirement for Cargo Securement Systems

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REFERENCE 2

Part 4 – Manufacturing Standards, Section 7 – Chain Assemblies

National Association of Chain Manufacturers, Welded Steel Chain Specifications

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NACM Conducts D/d Testing on Alloy Chain

NACM Conducts D/d Testing on Alloy Chain

National Association of Chain Manufacturers (NACM), representing domestic manufacturers of welded and weldless chain since 1933, has conducted D/d testing on alloy chain. D/d is the ratio between the curvature taken by the sling D, and the diameter of the component chain d. NACM alloy chain manufacturers supplied Grade 100: 9/32”, 3/8” and ½” and Grade 80: 3/8” for testing. Until this point, no published information was available for chain regarding D/d. NACM wanted to publish information to make recommendations on the minimum pin diameter for proof testing basket chain slings based on link deformation and rating/ derating of baskets and endless slings vs D/d ratio.

NACM testing results are shared below.

Conclusions:

1) Effect of D/d is the same for all sizes and grades of alloy steel chain.

2) Strength loss is highly consistent with D/d ratio.

3) No damage to chain at WLL (working load limit) with a D/d as low as 2.

4) Minimum D/d pin diameter of 5 recommended for proof testing basket slings.

5) Strength loss is 10% or less once D/d is 5 or greater.

The chart below shows reductions in working load limit of an endless alloy sling based on D/d ratio. Consult the manufacturer for any D/d below 2.

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Peter Cooke

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