capacity rate calculation for flat webbing slings
capacity rate calculation for flat webbing slings
(OP)
Hi,
I have read Lift-it catalogue and I found out it is very professional and useful . I have some questions in the subject and I'll be grateful for professional answers.
I found out that there is a direct relationship between SWL and the width of the strip (1600 lbs/in of width for nylon, 1000 lbs/in for polyester ), and I wonder what about the thickness of the strip? Does the thickness not affect SWL? Looking in manufacturers catalogues shows that it does affect SWL!?
Also, I have read WSTDA std and even there I realized that the material strength is expressed in the same manner/units (values 9800 lbs/in of width & 6800 lbs/in of width or 121.43/175 in SI units) without taking in account the thickness.
1) Could enyone explain to me why/where the thickness is hiding ? Also, what is the meaning of these values (9800/6800) in compare to the above 1600/1000 values?
2) At the above std (WSTDA-WS-1 2.10.3) there is an expression for rated capacity determination, and I'll be glad to get some typical values using this expression. By the way, is there a difference in the safety factor (5) used in USA according to the mentioned expression, and that used in the EUROPEAN (7)?
3) Is there any similar expression for round slings?
Thank you,
Guideon
I have read Lift-it catalogue and I found out it is very professional and useful . I have some questions in the subject and I'll be grateful for professional answers.
I found out that there is a direct relationship between SWL and the width of the strip (1600 lbs/in of width for nylon, 1000 lbs/in for polyester ), and I wonder what about the thickness of the strip? Does the thickness not affect SWL? Looking in manufacturers catalogues shows that it does affect SWL!?
Also, I have read WSTDA std and even there I realized that the material strength is expressed in the same manner/units (values 9800 lbs/in of width & 6800 lbs/in of width or 121.43/175 in SI units) without taking in account the thickness.
1) Could enyone explain to me why/where the thickness is hiding ? Also, what is the meaning of these values (9800/6800) in compare to the above 1600/1000 values?
2) At the above std (WSTDA-WS-1 2.10.3) there is an expression for rated capacity determination, and I'll be glad to get some typical values using this expression. By the way, is there a difference in the safety factor (5) used in USA according to the mentioned expression, and that used in the EUROPEAN (7)?
3) Is there any similar expression for round slings?
Thank you,
Guideon





RE: capacity rate calculation for flat webbing slings
RE: capacity rate calculation for flat webbing slings
Thank you for your reply, but I think that you are wrong, because even in one ply (as you can see in several catalogues)there is a significant difference in SWL when the thickness increases(what I am trying to say is that SWL for one ply 4 mm thickness is greater than one ply 3 mm thickness).
Regards,
Guideon
RE: capacity rate calculation for flat webbing slings
In the (WSTDA-WS-1 standard there is a list of available publications which I believe has some better information. If you look at a single rope of a particular construction you will see how the strengths are addable.
I would not try to redesign a synthetic fiber sling. Most companies give sufficient information to safely use said sling.
http://www.slingmax.com/pdf/new_composite_yarn.pdf
http://www.ropecentre.co.nz/chain19.html
http://www.americansling.com/grabiq.html
I had a friend that was in the wire rope sling business and as the synthetic slings came on the market he tested a great number of them for different companies and the government. His drawbar had 1.5 million pounds pull.
RE: capacity rate calculation for flat webbing slings
RE: capacity rate calculation for flat webbing slings
One thing that I had never seen in failure of synthetic fiber was that when it failed it failed in a least four places with resulting bangs.
http://www.samsonrope.com/index.cfm