Deck chains

[TNVS2]

I have been recently working with some freshers off of the LGH or Pffaf (silverblue) Columbas Macinnon, AKA PCM Rigging course, and have come across the use of the word "clutch chains".

I have been working in the industry for a fair while, and have always known such a device to be known as a "deck" chain.

 

Having just crossed the Irish sea, several times on a car ferry, and been a bit quick to the load decks, guess what I found holding the vehicles to the car deck securely....

 

DECK CHAINS! (what some may call clutch chains...)

Hundreds of them!

 

I appreciate that the use of these devives is to quite often bypass the clutch of a lifting motor, (not the clutch of a vehicle, incidentally...) (( I asked that one while on the ferry)).

 

Can we get our terminology right please!

[Pete]

I believe that clutch chains are a different

 

Deck Chain

 

Clutch Chain (Thanks Simon/Martin)

[Seano]

DECK CHAINS! (what some may call clutch chains...)

<snip>

Can we get our terminology right please!

 

Deck chains and clutch chains, at least in our industry, are two quite different things.

 

Deck chains and STAC chains are essentially the same. They're the long-link welded chains that look like this:

http://www.liftturnmove.co.uk/product_pics/stac_chain.jpg They're adjusted by using a shackle to select the number of "active" links required.

The 'deck' chain was indeed used originally to secure cargo to the deck of freight ships, the STAC chain is a development of the deck chain made specifically for our industry. (By CM - "STAC chain" is to "Deck Chain" as "Hoover" is to "Vacuum Cleaner")

Most people will tell you STAC stands for "Special Theatrical Alloy Chain", though in his (excellent) "Arena Rigging" Harry Donovan claims it was originally "Special Theatrical Adjusting Chain".

 

Clutch chains on the other hand look like this:

http://www.canford.co.uk/images/itemimages/tn/C20279.jpg

They're adjusted by using a gripping device (a chain "grab" or <ahem> "clutch") to include the number of active links required.

 

While STAC chains are an excellent product, arguably the best product available for building & adjusting bridles etc. in our industry, its technically illegal to use long link welded chain for lifting applications in the EU. Hence they're in a kind of limbo, unofficially their use is totally standard and widespread, but you won't tend to find much mention of them in official documents, or on the syllabus of formal courses, etc.

 

There have been some (well, at least one) very informative threads on this in the past. (Funnily enough, its while googling for this very thing that I first stumbled across the BR). A search for "STAC chain" should bring up some info for you.

 

hth

Sean

x

 

Edit:

Pete and I both posted at the same time.

http://us.st11.yimg.com/us.st.yimg.com/I/stageriggingonline_1896_10400058.gif

In the image of a deck chain Pete posted a link to (above), there's a shackle placed through one link between two others. This is WRONG, and "stageriggingonline" (not Pete) should hang their heads in shame.

[TNVS2]

Sean.

Myself and Pete have had a long running argument about this for quite a while!

The scandinavian ferrys seem to have adopted our theatrical devices, and are using them AS deck chains.

 

One thing that confuses me, is that the bottom triangular link is still the type of link that is used to lock vehicles to a car deck, on a deck chain. I can supply photos of said devices, as found on P and O ferries, and stenna lines in Scandinavia.

 

This has been bugging me for quite a while, and all the time served riggers still refer to these as deck chains, rather than clutch chains.

 

Pete is a great guy, and I hate crossing swords with him.

 

A couple of useful suggestions that may be worth passing on...

 

Cable-tieing shackle pins around the gate to stop them from unscrewing under load.

Cable-tieing what ever we decide to call them... hooks to the nearest lower link to avoid link from jumping. (ask PSL about that one!)

Bars of 6 take manfrotto stands over their SWL....

And ban super towers!

MY list of gripes is endless!

HTH.

I'm no fool. And sometimes hate being asked to rig when I know it is dangerous.

 

Incidentally, our deck/cluch chains, are 2M short link chains, with the deck fitting at one end, and an o-ring at the other.

 

I believe that makes them, oficially ,deck chains....

[Seano]

Quoted out of order, for clarity:

I believe that makes them, oficially ,deck chains....

There is no "official", with regard to the way we use terminology, because there is no governing body to dictate how we use the language. There is only convention, and if you want to make yourself understood within our industry, you'd be well advised to use the terminology the way its conventionally used.

 

I can quite understand why ferry crews would refer to any chain used to secure things to the deck as "deck chains", but this is irrelevant here. Within the theatrical/entertainment industry, the terms "deck chain", "STAC chain" and "clutch chain" are conventionally used as I have described.

If you want to use those terms differently, go right ahead, but expect to be frequently misunderstood.

 

and all the time served riggers still refer to these as deck chains, rather than clutch chains

Time-served marine riggers may well do, time served riggers within our industry, by and large, do not.

 

A couple of useful suggestions that may be worth passing on...

I don't get how most of these are relevant. I don't agree with any of your specific points, but it'd be off-topic to respond to them on this thread. If you'd like to discuss any of them specifically, please feel free to start another thread.

 

I'm no fool. And sometimes hate being asked to rig when I know it is dangerous.

Only sometimes? hmmm...

 

Sean

x

 

ps: You're not by any chance related to someone called Frank Wood, are you?

[Pete]

Bars of 6 take manfrotto stands over their SWL....

 

Are you sure?

 

Quote fixed (apologies again)

[Paul Jordan]

You need to be very careful... clutch chains are used for lifting/ suspending and are usually short link chains, howvere there are exceptions to this, the key is to find our if they are rated for lifting and covered by certification.

 

Deck chains and load binder chains, which is what are used on the back of trucks are a load restriant and should not be used for lifting.

[Locksmith]

I've always understood this to be a clutch chain for the simple reason that the metal bit used to shorten the chain is called a shortening clutch.

 

http://www.canford.co.uk/images/itemimages/tn/C20279.jpg

 

The two, three and four legged verions of these are frequently used for lifting loads with an off-centre centre of gravity. (Shorten one side to get the crane hook above the c-o-g before lifting)

 

my £0.02

 

cheers

 

Dave J

 

EDIT: Found a picture

http://backstagecrew.com/blueroompics/clutch.jpg

from here.

[Chris Higgs]

As I understand it, CM STAC was originally developed for lashing aircraft to carrier decks and used a lifting grade 80 material over the more usual grade 40, presumably because of the value of the aircraft. There are many 'deck' chains on the market and they are NOT all the same as STAC.

(Special Theatrical Alloy Chain (I think Harry was wrong in his book - I'll ask him)

 

Shortening clutches are a specifically designed piece of lifting kit made to fit grade 80 short link chain by the chain manufacturer concerned.

 

STAC has no CE mark because it is long link (greater than 3 bar diameters can pass the internal dimension of the 'air gap' in a link) and therefore cannot meet the Machinery Directive. Therefore it cannot be sold in Europe for lifting or provided by an employer for his employees to use at work. Lifting is often defined as when, should lifting equipment fail, a load would fall (or even roll) with potential to cause damage or harm as a consequence.

 

I have an e mail from CM stating they know of no incident ever arising from its use in the entertainment industry. However, unless they can CE mark it, or someone else is prepared to, you should not use it; the HSE have said as much.

This is a real pity because it is a strong, simple and effective means of adjusting bridle legs or secondaries. Sure they need to be used correctly, but the information is all available and you can learn to use it properly in minutes. If the links are overstressed (5.4 tonnes with a safety factor of around 5, so perhaps 20 tonnes or so.....) they start to narrow obviously in the mid section of the long sides. Bending and spreading links is a concern, but so is parking on a hill.

 

I wrote in a paper for the HSE/PSA and others some years ago that, in my opinion and most of the riggers I know, the use of STAC is without doubt the least of the concerns the authorities should have and lifting and rigging in the entertainment industry.

[Jivemaster]

There is a need to use kit as it was intended and found suitable and certificated. There is a similar argument about helmets, but sport climbing helmets don't comply with work regs.

Similarly lifting chain is diferently certified from pulling chain. similarly ratchet tie down straps as used for speaker stacks may be strong but dont have a SWL for lifting.

[Andrew C]

There is a need to use kit as it was intended and found suitable and certificated.

To a point; yes. However there are countless products that have been used in novel ways that have moved all sorts of industries forwards. To give one example, Teflon ; developed for the aerospace industry, and now found on frying pans.

We need people to be imaginative and for regulatory authority to find ways to allow innovation, and not stifle it unecessarily.

 

This comment is "in general" rather than specific to STAC or any other chain.

 

PS:- If STAC was designed for lashing aircraft down, why call it theatrical??

[Seano]

PS:- If STAC was designed for lashing aircraft down, why call it theatrical??

STAC was designed (or rather adapted from a pre-existing product, those extra strong deck chains for aircraft) to be used exactly the way it is used.

 

Check this bit of Chris' post again:

STAC has no CE mark because it is long link (greater than 3 bar diameters can pass the internal dimension of the 'air gap' in a link) and therefore cannot meet the Machinery Directive.

Long-link welded chain can't be CE marked for lifting applications, and therefore can't legally be used for such in the EU.

 

I imagine the directive is written that way because it would be dangerous to use a long-link chain (even one as strong as STAC) as a chain-sling, but we don't do that, ever. The thing is, in the grand scheme of things we're a teeny tiny little niche industry, and the fact that STAC is undoubtedly the best and safest way of doing what we do with it in our obscure little niche was overlooked when the regulations were drawn up.

 

In the US, where STAC is manufactured, it is used "as it was intended and found suitable and certified" (thanks Jivemaster). Over here its used as it was intended and found suitable, but it can't be certified because the law (in this case) is an ass.

 

Question for Chris:

Is it possible that the Machinery Directive might be amended to allow us to use STAC legally? Is there any lobbying going on, anything in the pipeline that might result in a change in the future?

 

Actually using it legally/illegally doesn't concern me at all (as you said, least of our worries).

But it does concern me a bit that we can't talk about how to use it, and include the do's and don'ts of using STAC in our formal training.

I'm not surprised that there's never been an incident resulting out of the use of STAC, for that to happen it would have to be severely abused/misused. We don't make that any less likely by not teaching people how to use it correctly when they take courses (and, ultimately, assessments).

 

Sean

x

[ampcats]

a similar story to tallescopes - the law-makers do not take into account how a certain group of users have quite safely historically used the product.

 

how about banning petrol cars because they create explosions and explosions are bad...

[Jivemaster]

We need people to be imaginative and for regulatory authority to find ways to allow innovation, and not stifle it unecessarily.

 

Wouldn't that be nice! Alan Turing would be living with the partner of his choice and silicon valley would be in the Pennines. Remember the navy saw the prototype hovercraft and classified it then wouldn't clear Cockerell -the inventor- to continue work on it.

[leofric]

Ok, so we have established that STAC chain is not certified for use in the EU. Thank as ever for your informative post Chris.

 

My question then is what legal alternatives are there for the job of quickly and easily shortening the leg of a bridle?

 

Are clutch chains ( being a chain that can be made shorter by use of a metal clutch as illustrated above)generally CE marked and legal for use?

 

Are such pieces of equipment authorised for use in Germany?

 

Your thoughts would be appreciated whilst I go off and do some googling.