SWL

[timmiddleton]

trying not to sound really silly, what does SWL stand for? I guess the WL is weight limit but it would just be nice to find out ** laughs out loud **

 

Tim

[david.elsbury]

Safe Working Load, as far as I know.

[TomLyall]

Yes, Safe Working Load.

 

30 seconds on google confirms that.

[Locksmith]

SWL = Safe Working Load, but it can vary depending on the slinging method used, so beware. Another one you may come across is WLL (Work Load Limit) which is (in a very small nut shell) the amount that the sling can handle with no modifications hitches etc.

[Gilly]

Although if memory serves there is a distinction between WLL and SWL. I believe that it is that one has had samples destructively tested, and the other has had safety factor designed in, hopefully someone out there can remember which way round that is. Although of course in practice they mean the same thing.

[MartinGreen]

Safe Working Load is the load that is decreed by a competent person that is safe to be used in an environment.

 

Working Load Limit is a newer term but it is the limit that the equipment can be loaded to when used correctly. This is usually what the equipment comes supplied with.

 

So in effect, even if the WLL from the manufacturer says 1t, a competent person can decree that this is not the Safe Working Load in a particular environment. But the SWL can never be higher than the WLL as this is set by the manufacturer.

 

So sometimes the SWL may be decreased below the WLL where for instance a higher factor of safety is required (such is with hoists with a 10 : 1 safety factor).

 

I know this from my time in Industrial Lifting, where normally a chain block would be rated at 1t, but in a mining application, it was de-rated to 500KG because the mines act upped the safety factor on the blocks.

 

Oh the joy of lifting legislation :blink:

[Locksmith]

In a number of draft ENs, the term Working Load Limit (WLL) is replacing SWL as the load beyond which lifting equipment should not be used. WLL is the load value assigned to the 'maximum' safe working load under ideal conditions (by calculation) and in most cases WLL will be the same as the SWL. However, depending on the conditions of use, it may be necessary for the competent person to reduce the WLL to a practical SWL; it is this figure which should be marked on equipment to comply with reg.7 (and be used in determining its safe use for the purposes of reg.8). SWL may be the same or less than WLL but can never be more.

From LOLER 98

 

Well, I did say my previous reply was in a very small nutshell. This reply is in a slightly larger one.

 

In recent years though, many round webbing slings have been marked with a WLL which refers to their use in a straight pull only. This is where confusion has arisen in the past. The sling would be marked with a 1t WLL but under certain conditions has a SWL of 2t. ie in a cradle hitch, a roundsling with a straight pull WLL of 1t can lift 2t (when new and under perfect conditions etc.).

[Chris Higgs]

WLL (working load limit) should generally be regarded as meaning the same as SWL on an item of lifting equipment.

As Martin says, the employer's 'competent person' de-rates the item according to use.

If there is the manufacturer's WLL of say 2000 kgs, and a further SWL marlked of 1000 kgs, you use the lower figure as the SWL.

The manufacturer is not necessarily putting the item on the market for a particular purpose, for example our (overhead) use of yachting pulleys. They often have a WLL of X kgs with a safety factor of 2. We de-rate according to use and apply a safety factor of say, 8.

 

WLL is often used in the US as we use SWL in the UK and a better way of describing it might be a the manufacturer's design load, including any safety factor quoted.

 

WLL does NOT only refer to a straight pull.

[Locksmith]

In recent years though, many round webbing slings have been marked with a WLL which refers to their use in a straight pull only.

<{POST_SNAPBACK}>

 

WLL does NOT only refer to a straight pull.

<{POST_SNAPBACK}>

 

Having re-read my post I see where I have been misunderstood. I was refering to the practice of marking the WLL on a sling label and giving no details for the various configurations. This would then be the SWL in a straight pull and other configurations may then be higher or lower than that stated. I was not meaning that WLL only refers to a straight pull. As it says in my quote from loler98

 

In a number of draft ENs, the term Working Load Limit (WLL) is replacing SWL...

[Chris Higgs]

The current standard (BS EN 1492-2) was published in 2000, same as the guidance.

The sling should bear a label showing the configurations that affect the strength. Although this is not actually what the Directive requires, it is the way the majority of quality manufacturers do to comply and allow them to use the CE mark.

You should only be using CE marked slings these days.

 

WLL is the manufacturer's maximum load, SWL is the reduced value to take account of the particular circumstances of use.

BS 7906 requires a factor of safety of 8:1 for overhead lifting (should you choose to use it).

BS EN 1492-2 requires at least 7:1 to reflect the requirements of the Supply of Machinery (Safety) Regs.

So if you need to use the sling to the max, take the marked SWL/WLL, multiply by 7 to obtain the minimum breaking load (MBL) and then divide by 8 to obtain an 8:1 factor of safety against failure.

 

2000kgs x 7 = 14000 kgs MBL.

14000kgs / 8 = 1750 kgs SWL (@ 8:1)

 

I would expect that in the majority of entertainment industry uses, a 2000kg sling will actually often achieve a factor of safety of at least 8 when the mode factor and the load value are considered.

[Brixton]

2000kgs x 7 = 14000 kgs MBL.

14000kgs / 8 = 1750 kgs SWL (@ 8:1)

 

I would expect that in the majority of entertainment industry uses, a 2000kg sling will actually often achieve a factor of safety of at least 8 when the mode factor and the load value are considered.

At the risk of seeming a big wuss I always used to go for the next colour up if I thought I was going to be anywhere approaching the SWL

 

 

I found it very sobering sitting in the spot position at Wembley watching the rig bounce up and down in time to the music.

[Nick Evans]

I found it very sobering sitting in the spot position at Wembley watching the rig bounce up and down in time to the music.

Especially when you knew who rigged it (only teasing Brix).

 

I am sure it will happen and there is no reason for it not to, but I have yet to see CE marked O-rings, shackles, steels, clutch chains or STAC chains.

[MartinGreen]

I am sure it will happen and there is no reason for it not to, but I have yet to see CE marked O-rings, shackles, steels, clutch chains or STAC chains

 

This is an excellent point Nick. Steels should always be marked with the CE mark on the ferrule, O rings should be accompanied by a tag, but because in general industry they are a componant part, they are not stamped. The tag is stamped when it is used in a chain sling.

 

Shackles you will find these days (should!!!) be embossed with the CE mark. I know crosby and CM both do this. If the shackles you buy are not, then in essence you shouldn't be using them.

 

In theory everything that is used as a lifting "machine" should be marked with the CE mark. But you will sometimes find that something like an O ring is not, because it is classed as a component part of a lifting machine.

 

STAC chain was last week discussed by the LEEA. If you talk to any chain maker, they will tell you that under no circumstances should STAC be used for lifting or suspension as it doesn't meet EU legislation (I think its EN818 but I could be mistaken). The only chain that can be used for lifting and suspension is short link chain.

 

All that said, in the LEEA meeting, there were many present who stated that they thought the use of STAC was fine. So if the body that is supposed to offer the Lifting Industry guidance doesn't knoe which way to go on this, what hope is there for the rest of us.

 

In my opinion and experience, LEEA is an old boys network that is more geared around serving members interests than it is acting on legislation. I have sat in more meetings there that got nothing resolved than I care to mention.

 

SO to sum up, everything you use that has been manufactured since 1995 should be marked with the CE mark. Be it a chain, O Ring or anything else.

 

P.S My STAC chains are all CE marked because they have to be! They also carry a European Manufacturers CE Certificate. I can't afford to get caught with my pants down (as it were!!!).

[Chris Higgs]

HTH!!!

 

Supply of non CE marked products for use at work in Europe is in theory illegal where there is a 'Directive' that relates to the product.

Lifting accessories = Machinery Directive, therefore must be CE marked.

Non CE marked product should therefore not be provided for use by an employer even though it is available. (Reg 10 of PUWER)

 

All 'lifting accessories' that is equipment that cannot provide any lifting by itself but is a complete piece of equipment should be CE marked (might have been 92, can't remember the transition period). Put another way, a section of truss or a length of un made wire rope isn't CE marked because it isn't 'finished' and may be used in a number of ways.

STAC (Special Theatrical Alloy Chain) is slightly different. I don't think it is CE marked, it does not comply with the requirements of the Machinery Directive, thus our UK Supply of Machinery (Safety) Regs.. (Isn't this exciting...)

This Regulation specifically excludes welded long link chain for lifting.

 

CM (who have been very helpful to me in trying to sort this out) AFAIK don't CE mark theirs because they make it it in accordance with US standards, not European ones.

There are other long link alloy steel chains not made by CM and are therefore not STAC; these may be CE marked, I don't know, but technically it can't be against the Machinery Directive which is the relevant bit of Euro-law. They are used in the fishing industry and I believe sugar cane conveyor chains, neither of which are lifting applications.

 

(Martin, please confirm your STAC is CE marked via an e mail - it could help a lot. Who marked it? CM or the importer? The person 'putting it on the market' has the duty to certify it against the standard and hold the technical file AFAIK.)

 

Some venues have taken all their deck chain out of service, although this is an insurance issue rather than a safety issue per se.

I have been fighting this battle on behalf of us all since November last year and written a paper about it for the BJAC (HSE committee).

 

The latest from HSE AFAIK is a big 'NO'.

Crazy.

[MartinGreen]

The update on STAC as I know it (this is as of this week).

 

As Chris correctly states above, so far as the machinary directive and PUWER are concerned, you CANNOT UNDER ANY CIRCUMSTANCES use STAC or "Long Link Chain".

 

For me, my supplier (rightly or wrongly) was CE marking it and I have the declaration from the manufacturer (again rightly, or wrongly).

 

At great cost to me personally (I have barrels of the stuff in stock), I have ceased selling STAC chain or all the above reasons. As crazy as it is, the law is the law and I may agree or otherwise, but you have to obey the laws of the land, so as of this week, I have removed STAC from sale.

 

The real bummer is, I had to turn down an order for over 100 pieces. :blink:

 

I have spoken at length with a European chain manufacturer and basically there is no way that you should use STAC in their opinion, no matter how overrated it is.

 

It fails to conform with EN818-2 (I think) which is the European standard for ALL chains for lifting purposes.

 

So, as of now no STAC for sale from me. Although I know that people are still selling it.

 

The solution? Clutch chains I'm afraid. We do locking ones, so at least they dont jump out and bite you when you least expect it. I grant you, their not as good, but they are the nearest LEGAL thing you can use.