NACM Conducts D/d Testing on Alloy Chain


by  on February 8, 2011

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.


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.


{ 2 comments… read them below or add one }

Peter Cooke Peter Cooke April 12, 2011 at 11:08 am

Hello Hisham,
Thank you for your kind words and for taking the time to read our blog. We appreciate what you are doing for us in Egypt!

Hisham El Banna April 10, 2011 at 4:28 pm

Peter ,
Good article particularly from a CMCO Trainer. Our company CosmoPetra is an official Distriburor of CMCO products in Egypt .

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