Measure Twin-Path® Slings under load to ensure accuracy.

Question: I have a question concerning (4) TPX9000 x 60 ft.  We have measured these slings and it appears that the slings are now different lengths, some having up to a few inches of difference.  Could you please send me information concerning the proper way to measure the slings, and if there is any reasons that the slings could have changed in length.  I have had problems explaining this difference to our customers and this has created some challenges on some recent lifts.

Answer:  Twin-Path® sling length does not change over time, although it may seem to in certain situations.  The load bearing internal K-Spec® strands do not shrink at all.  However the Covermax® double cover used for these slings is made from a bulk nylon material and nylon does shrink.  Therefore, the cover’s shrinkage would create an inconsistent measurement of the sling length when it is not under tension.  Apply an equal tension to each sling as you measure them to verify sling length. Please refer to Slingmax® Technical Bulletin #4  for measuring information: 
In short this is what it says in the body of paragraph 2:  It is important to note that Twin-Path® Extra slings have a bulked nylon double cover which protects the K-Spec® core yarn inside. Nylon shrinks when relaxed and stretches under load whereas K-Spec® does not. Therefore, roundsling covers will show some expansion and contraction over time.  This is normal and does not affect sling length tolerance.  Floor measuring, especially with used slings is not always accurate.  To ensure optimal accuracy, we recommend measuring Twin-Path® Slings under load even if it is only 10% of rated capacity.