On our website is a lot of information available. For example, every brand has its own product information and cases. Quick tips are available on the tips and tricks section. Technical blogs written by Rinus Bakker are available to read below. More depth information is available in our brochures and Black Book. You can read the English Black Book below, of visit our brochures section for the Black Book in other languages.
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|Blackbook - English
Rinus Bakker, a respected man in the market, wrote two blogs about the uniqueness of lifting shackles and about the identification of lifting shackles. These blogs are shown below. The latests blog will also appear on the Prolyte Campus Facebook page. Do you have any comments or do you want to discuss something? Let us know at the Prolyte Campus Facebook or send us an email.
Believer, Faithful or Fanatic?
We all have our favourites. Whether it’s a performing artist, sportsman, team, or even politician. Some people are not just fans… they can be fanatic.
At least that idea came to my mind after receiving this picture.
The issue: The truss in the front looks very much like the B-100 from Prolyte. A strong type of module for sure – to use as temporary stage roof beams or mother grid. But are they temporary stand-alone towers as well?
The other two towers in the picture are made of (stronger and rustier!) steel. And these still are fitted with stabilizers.
The answer: To see is to believe? In this case I want to see a structural report. And a convincing base module. And stabilizers. Or a cut through picture, where we
might see a complete 3m section poured in 10 tons (or so) of concrete all resting under the ground. And I would like to know what the calculations assume as a limit
to the wind speed. And my believe will grow when seeing the insurance policy of the company that put it up, and the insurance of the organizers…
The verdict: We never can exclude all risks from human life. But this kind of believe in B100 truss is one that we should be able to verify and control. Proper stabilizers, ballast and base sections should be part of any type of tower system. The shown type of truss-faith should not accidentally change into truss-terrorism.
Rinus Bakker, 10 October 2013
Soft steels - use on structural beams?
Since 1997/8 the entertainment industry has been graced with a ‘new’ product. A kind of round sling but not filled with thousands of polyester yarns but instead having a 2-3mm Ø wire rope going around for 25 to 30 times.
In the Netherlands the inventing company (Roodenberg Staalkabels) named them ‘Soft Steel’. In the USA another company (Lift-all) completely independent developed the same type of product and introduced it as ‘Steel Flex’.
The issue: Is this product – originally designed to cope with high temperatures of lighting instruments on the trusses – suitable to be used for other purposes? Can you use it to wrap a beam and make a basket or choke with it?
The answer: “Mais oui, bien sur!” meaning so much as “Yes most certainly!” (and that’s enough French for today). But the answer is correct. Nothing is against slinging structural steel beams with soft steels.
The D/d ratio is better, so the cutting hazard of a sharp edge is less. The distribution of the force is along a wider surface, so less local friction stress and better longevity of beam metal coating. Wooden beams will also be happy with these types of slings.
Further it has no bulky terminations like a mechanical splice or Flemish eye that reduce the effective length of the sling body allowed being bend.
Another great feature is the possibility to push or pull the soft steel through narrow slots on top of beams or narrow holes in walking grids as there are no unnecessary thimbles that beef up the termination’s eyes.
The verdict: Yes you can use soft steels for slinging of structural beams. If you want to be fast, efficient and safe buy them as ‘basket soft steels’ with a special sling hook already connected to it.
Rinus Bakker, 24 September 2013
As stated in a previous blog: don’t waste your money on some inspection company to check your shackles if you can easy learn to do it yourself.
The issue: Notified Body inspectors barely do a serious job in checking your shackles, because they don’t need to. But they still send you an invoice, so you might be better off to do the job yourself.
The reply: Any user should know the company that manufactured his shackles. Most manufacturers have a distinguished colour of their shackle pins; so strange colours or no colours at all could be a warning that the item might be strange inventory. The manufacturer will showcase drawings with specific dimensions for the specific load rating sizes.
You don’t need a set of callipers all the time, but a strange shaped shackle of a well-known brand is a warning sign. Any change in dimensions of over 5% should be a reason to investigate what happened, and any change of 10% or more is reason for discard and still do the investigation.
One of the most common mistakes – and a potential hazard – is using the wrong bolt in the shackle. BMW is BMW and never use a Mack-part in a Mercedes, or a GM-part in a Volkswagen.
It just is not safe!
The picture on the right is no fiction, this could happen!
Wear can happen more easily in our business, since people drag bridles across a concrete arena floor, that will act as sandpaper or even a grinder. The most obvious positions that could show wear are indicated on the right. In our business the internal wear might be less likely, but nevertheless a risk.
The verdict: Always check the dimensions, easy rotating of the pin, wear of the shackle and the WLL mark.
When a grinder is used to remove the brand name (or any other identification), there should be serious checking on other aspects as well, to start with the mind-set
of the guy who did that.
Rinus Bakker, September 6, 2013
Slinging methods: do we know ‘m all?
The topic of slinging entertainment trusses has been hovering over the market for about three decades. Mainly because the open character of the truss structure allows for so much more ‘routes’ for a sling compared to the ‘classic’ solid beams…
The issue: Slinging of trusses is of course not the most common cause of accidents that involve truss structures. Beyond any doubt that would be overloading of the truss span itself or overloading of a chain motor. Negligence in planning or maintenance does play a role. And in outdoor situations it is undoubtedly wind, wind or wind. But slinging does play a role for the internal forces in the truss module members. And at one point this can lead to stresses causing failure, either as a direct collapse or in a fatigue induced manner.
The answer: When categorizing the pro’s and con’s of method variations it must be clear which one is discussed, so a name (or rather a …number) is needed. 15 years of collecting slinging methods still has not reached a ‘saturation’ point: every year of few ‘new variations’ keep popping up. Below some examples are shown of over 200 slinging variations on a square truss, with one sling only in a ‘basket’ set-up.
The verdict: It looks like imagination has no limits and some should really be in a Museum of Modern Art. To be continued.
Rinus Bakker , August 19, 2013
Identification of lifting shackles
Yes – a bit more about these things. Real cash-cows for inspection companies if you want to buy their annual paperwork that is often confused with an inspection.
The issue: All lifting components that can be affected in their safety as a result of use, abuse, wear and so forth shall be inspected at least once a year. Thus no sense in denying shackles shouldn’t be.
The reply: Nowhere in EU-Directives, Act’s, Laws or Regulations is specifically stated that the annual inspection of shackles must be done by a government recognized inspection company or a Notified Body. Buy the right shackles and be less worried on the subsequent annual paperwork.
First thing is to make sure using shackles that are designed an manufactured for lifting purposes. Most nations require a minimum amount of identification on the shackle. The picture + table on the right compares the situation of the EU with that in the USA and Russia. The position of these markings is free.
A) Manufacturer name or name-code
B) WLL = Working load limit – the rated safe working load for general us.
C) CE marking. Referring to a type IIA declaration by the
D) Diameter of the body or leg – in mm’s or inch.
E) Material alloy, in a number or code
Do you find all these mandatory ID’s then use them. An important thing that should be considered is that shackles are not the weakest parts in our systems, in most cases the wire ropes are.
The last one is an overall risk assessment: in the range of rigging accidents that have hit our industry in the last couple of decades, failure of a lifting shackle has never been the cause.
The verdict: Inspect them yourself, as will be explained about in a next blog. Put the accredited (expensive) attention to where it is more (cost-) effective…
Rinus Bakker, August 7, 2013
Uniqueness of lifting shackles
The first one that comes to mind, reading shackles will be the common type used in the entertainment business, known as: screw pin anchor shackle, and also referred to as screw pin bow shackle. The following remark however is just as valid for this one: the screw pin chain shackle, or D-shackle.
The issue: Often the remark is heard that the body (the Ω omega or U-shaped part) of the shackle, and the shackle pin (or bolt) are a unique combination, that should always stay together.
The reply: That type of remark is absolutely false.
In the manufacturing plant the two parts are produced complete separate of each other in different machines and processes. Only at the very end the two will meet, in order to be shipped out.
Somewhat similar to the tapered steel pins and bi-conical connectors of Prolyte that only will meet the trusses at the first trail build at the plant or – more often - the first production the user sets the into action.
The verdict: You can mix the parts of one manufacturer in one capacity-range, but don’t mix shackle parts of different manufacturers, even if they have the same load rating. Just as you should not mix components of truss brands that make bi-conical connector systems.
Rinus Bakker, July 31, 2013.