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Posted By chiefinspector
I work for an oil service company that supplies drilling tubulars to the offshore oil & gas industry.
We recently had a complaint from the dock crew who were loading the tubulars onto the boat that the slings were of the wrong SWL.
The slings were rated to 3t and each lift was coming in at 2.7t. It is common practice to double wrap the slings but we were told that by doing this, the capacity of the slings had been reduced by 20%.
This is the first time that we have come accross this problem and i would like to know if anybody knows if this is correct or not and if there are any guidelines that state this?
Thanks
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Posted By D H
The information you were given is correct - double wrapping reduces SWL by 20%
Dave
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Posted By peter gotch 1
D H
It used to be in a BS - do you know what is the relevant BS EN.
With figures indicating downrating in different confifugurations.
I did a quick search on Technical Indexes but gave up as too many hits.
Regards, Peter
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Posted By D H
Peter - don't know the BS EN from memory - and have no access for a wee while.
Check the labels on your rope slings - they will show the SWL per the way the sling is used - and may indicate the number?
Dave
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Posted By Peter MacDonald
I would recommend getting a copy of 'Lifting Equipment, A users pocket guide' published by the Lifting Equipment Engineers association along with The Lifting Engineers Handook also by LEEA.
They provide mode factors when for use of sling among a ton of other lifting guidance (excuse the pun).
Not too pricey either.
Pete
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Posted By chiefinspector
Thanks for the quick response. Looks like we have been doing this wrongly for some time now and i'm sure we are not the only ones. Just goes to show that you learn something new every day.
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Posted By William
Also dont forget your angles, i:e
At 0 degrees 2 slings will lift half the load each, so they would life 1:5t each, at 90 degrees they will lift 70% of the load, so if it was 3 tonnes with the slings at 90 degrees then the load on each sling would be 2:1 tons, then if you have choked it reduce by a further 20%, which then reduces the swl again to around 1:6t per sling, and you should never go above an angle of 90 degrees, also your slings should be evenly spaced. Also use bullbogs and cable ties so the slings dont come out during transit
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Posted By William
If you need more info contact me, i work offshore in this area.
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