Difference between grades of chain

[MPowers]

I do have to respectfully take some slight exception to your Theatre face articles on chain. The blogs are terrific and the information is invaluable, however, there is some disagreement as to appropriate product for trim chains. The biggest issue is the definition of "Overhead Lifting". As stated in the following papers from the JR Clancy web site, overhead lifting as defined by ANSI et. al. refers specifically to a chain that is reeved over a cog wheel or drum.

http://www.jrclancy.com/Downloads/TrimChains-ESG.pdf
Stage Rigging Systems and Equipment for Theater, Arena, School and Concert Hall

 

[teqniqal]

Although "ANSI, et al" (any chance you could cite a specific standard?) may refer to chain run over a cog wheel (i.e. a chain motor drive) as the only circumstance as being the 'official' definition of 'overhead lifting', there are many other documents that speak differently. Rarely is anything suspended in the entertainment industry without it potentially being 'overhead'. You can call a cow a duck, but it's still a cow.

The 2010 NACM Welded Steel Chain Specifications specifically state in section 2.1: "Grade 30 Proof Coil Chain - General purpose, carbon steel chain. Used in a wide variety of applications. Not to be used in overhead lifting." (Bold emphasis is theirs.) Only Grade 80 and above are permissible for overhead lifting by NACM standards. The standard further defines 'overhead lifting' in section 3.4: "That process of lifting that would elevate a freely suspended load to such a position that dropping the load would present a possibility of bodily injury or property damage."

The Columbus McKinnon (CM) "Lifting, Pulling & Binding Products Manual" states "Grades 63, 80, and 100 are alloy chains and due to their strength/toughness properties are the only chains recommended for overhead lifting by NACM, OSHA Standard 1910.184, ASTM Standard A391 and ANSI/ASME Standard B30.9." and Table 1 in that document only shows "Recommended for overhead lifting by NACM, ASME, and OSHA." for Grade 80 and Grande 100 chains - it only acknowledges that Grade 63 chain "May be used in rigging and lifting applications."

The ESG 'Trim Chains' article cited also has numerous references to standards that say the same thing.

The German publication "Berufsgenossenschaftliche" Informations Guide (BGI or "Safety for Productions and Events - Loads Suspended above Persons" 2007-03-13) describes Grade 8 (80) chain as being more suitable for Live Event rigging. In that document it describes the chains being used for 'freely suspended' objects and where the chain is constrained by being bent over an edge or wrapped around an object.

And in a more general case, commercial riggers worldwide consider all lifting to be 'overhead' and make their equipment selections according to internationally recognized standards (DIN, TUV, BS, etc.) for safety.

Bottom Line: Don't use under-rated or under qualified equipment for overhead lifting or rigging. It doesn't matter if it is part of a chain-motor hoist, or not - it is still OVERHEAD. If you won't let your children sleep under it, then don't do it.

 

[MPowers]

I cannot find the specific ANSI code # however, from the JR.Clancy Website.
"...define lifting as 'lengthening or shortening the chain itself by mechanical means, i.e. a chain hoist'. Dead hanging includes raising or lowering an object attached to a length of chain, as long as this isn't accomplished "by the mechanical lengthening or shortening of the chain itself". "When used with in the appropriate workload limits, proof coil chain may be used for dead hanging."

Further from JR Clancy website:
OSHA May 1983, "proof coil chain may be used in chain slings if used within the manufacturers recommendations."

In addition, Grade 80 chain is unacceptable and unusable as a trim chain in any application. Why? Grade 80 chain links have such a large wire diameter that any appropriate load rated connection, such as Crosby Loc-a-loy links, missing links, or load rated forged shackles, cannot be used in intermediate links, only in the free end. This means grade 80 chain is OK for suspending, but not for adjusting trim height.

Combine this with the fact that that 1/4" proof coil chain has a higher WLL than 1/4" GAC, 3/16" Proof coil greater than 3/16" GAC, in fact, properly used, more than twice the WLL of the cable. Properly used, the chain is wrapped around the pipe batten and connected to the cable eye. This means that each section of the chain is supporting only 1/2 the load. So, even in the single path, straight link configuration spec'd by many architects for dead hang situations, the chain is still stronger than the cable it connects to. 1/4" Cable is rated at 875# WLL, 3/16" at 575#. The chains are rated at 1250# and 750#, higher than the cable. Destructive testing by D2 Flying Effects, Clancy, ETC et. al. show the wire rope always fails before the chain.

For what it's worth, the following companies, who employ licensed engineers, all agree that grade 30 proof coil chain is acceptable and suitable for trim chains and other dead hang theatrical rigging conditions.
J.R. Clancy, Sapsis Rigging Inc. (SRI), Texas Scenic Company (TSC), SECOA, H&H Specialties, THERN, Mutual Hardware, Norcostco.......I'm sure there are other companies that also approve of grade 30 proof coil chain as appropriate for trim chain.

While my engineering degree is only a bachelors and I have never become licensed, (not necessary for university faculty in technical theatre, Freelance Design, film FX or LORT TD work) I do have a fairly good background in the mechanics and implementation of rigging and mechanical forces.

If you have questions I strongly urge you to actually read the following link:
http://www.jrclancy.com/Downloads/TrimChains-ESG.pdf

 

[MNicolai]

I cannot find the specific ANSI code # however, from the JR.Clancy Website.
"...define lifting as 'lengthening or shortening the chain itself by mechanical means, i.e. a chain hoist'. Dead hanging includes raising or lowering an object attached to a length of chain, as long as this isn't accomplished "by the mechanical lengthening or shortening of the chain itself". "When used with in the appropriate workload limits, proof coil chain may be used for dead hanging."

Further from JR Clancy website:
OSHA May 1983, "proof coil chain may be used in chain slings if used within the manufacturers recommendations."

In addition, Grade 80 chain is unacceptable and unusable as a trim chain in any application. Why? Grade 80 chain links have such a large wire diameter that any appropriate load rated connection, such as Crosby Loc-a-loy links, missing links, or load rated forged shackles, cannot be used in intermediate links, only in the free end. This means grade 80 chain is OK for suspending, but not for adjusting trim height.

Combine this with the fact that that 1/4" proof coil chain has a higher WLL than 1/4" GAC, 3/16" Proof coil greater than 3/16" GAC, in fact, properly used, more than twice the WLL of the cable. Properly used, the chain is wrapped around the pipe batten and connected to the cable eye. This means that each section of the chain is supporting only 1/2 the load. So, even in the single path, straight link configuration spec'd by many architects for dead hang situations, the chain is still stronger than the cable it connects to. !/4" Cable is rated at 875# WLL, 3/16" at 575#. The chains are rated at 1250# and 750#, higher than the cable. Destructive testing by D2 Flying Effects, Clancy, ETC et. al. show the wire rope always fails before the chain.

For what it's worth, the following companies, who employ licensed engineers, all agree that grade 30 proof coil chain is acceptable and suitable for trim chains and other dead hang theatrical rigging conditions.
J.R. Clancy, Sapsis Rigging Inc. (SRI), SECOA, H&H Specialties, THERN, Mutual Hardware, Norcostco.......I'm sure there are other companies that also approve of grade 30 proof coil chain as appropriate for trim chain.

While my engineering degree is only a bachelors and I have never become licensed, (not necessary for university faculty in technical theatre, Freelance Design, film FX or LORT TD work) I do have a fairly good background in the mechanics and implementation of rigging and mechanical forces.

If you have questions I strongly urge you to actually read the following link:
http://www.jrclancy.com/Downloads/TrimChains-ESG.pdf

Similar argument to the one I made in our Trim Chain thread.

NACM's definition of Overhead Lifting has a large caveat in it, which is in regards to "freely suspended" objects.

Overhead lifting: that process of lifting that would elevate a freely suspended load to such a position that dropping the load would present a possibility of bodily injury or property damage.

To which trim chains do not fall into the category of Overhead Lifting, because battens are not freely suspended.

JR Clancy's argument is this, as per the document MPowers linked to:

The wording is clear; by our interpretation it was carefully written to cover very specific applications where the notable wording "freely suspended" must apply. Whether or not something is freely suspended is a critical aspect of determining suitability for a trim chain application, and one that is nearly always overlooked in discussions about trim chains. Understanding the implications of freely suspended is important. By standard definitions, it implies a concept of hanging something in an unrestrained manner or without restriction or limits. We can easily interpret how NACM standards and OSHA regulations are intended to apply to circumstance such as those present on construction sites: a crane lifting a load on a single (freely suspended) cable.

 

[BillConnerFASTC]

So in researching this topic for SML (dual listers please disregard) I took exception to some of the comments above. Sorry this is repetitious but this thread came up 3 or 4 on google search and I feel it's important to "complete" the record.

In no particular order, both SECOA and Clancy have alloy chain that is designed for theatrical use, so check out those data sheets and the OSHA sections they reference.

Second, the whole discussion over "overhead lifting" and "freely suspended" has been totally twisted. Some years ago, I spoke with every member of the NACM, both the companies and the individuals at the table when the standard was written and all of the overhead lifting and alloy chain language was developed. I have shared with them photos and drawings of trim chains. About half said with certainty that this was an overhead lifting application and half got their lawyers involved and would not answer. I firmly believe that if you want to know what was intended (and there isn't a court tested precedent) that you should seek that interpretation from the writers. In this case, the reason for "freely suspended" is so far from what people in entertainment technology have tried to use, that the NACM director chuckled.

Third, the Clancy reference to the May 1983 OSHA statement is a little misleading. The whole statement in it's entirety from OSHA:

"The use of other than alloy steel chain is not prohibited specifically in 29 CFR 1910.184, but only alloy steel chain is recommended by chain manufacturers for overhead hoisting. Proof coil and high test chain is used for purposes where failure of the chain would not endanger human life or result in serious damage to property or equipment. Proof coil and high test chains should only be used in accordance with the manufacturer's recommendations."

It seems simple to me. OSHA and the chain manufacturers say trim chains are overhead lifting and alloy chain shall be used. The fact that SECOA and Clancy have products for the application that comply with the regulations and add insignificant cost to a basic lineset makes this all a simple discussion.

Sorry for the rant but I don't want to leave just one side and what I feel is inaccurate information. Also, I want to be clear, that my position is about the regulations and what is required by law, not what makes sense, is sufficient design, or is safe. If you want to argue the engineering issues, don't bother, I've heard them all, and suggested that those that are interested undertake changing the regulations which require alloy chain be used for trim chains.

 

[MNicolai]

@BillConnerASTC, have you contacted Clancy about their published interpretation of what "freely suspended" means?

From a regulatory perspective, I'd say that the lack of legal precedence in this matter is where "freely suspended" throws a wrench in the works. I'd prefer to not see our industry test the bounds of that though and get that term defined via a legal preceding following an accident. Instead, I'd want to see either/both the OSHA and/or the NACM standards amended to reflect the intentions of the original writers.

I understand the case you're making, but I fear that just because the drafters of the original clauses and definitions intended otherwise, does not mean that Clancy's interpretation is incorrect. Clancy's interpretation of "freely suspended" may still be valid until/unless legal precedence declares otherwise, or until/unless NACM and OSHA amend their standards to more clearly reflect what they consider the terms "overhead lifting" and "freely suspended" to mean.

------

I want to point out for anyone following along or finding this via Google -- whether or not you follow regulations, if you design any form of rigging that gets someone killed, pointing back at the regulations and saying you followed them to the tee won't get you off any hooks, even if you've got an argument you want to make about the legal definitions of "freely suspended" or any other technicalities you want to argue.

Whether or not someone you use overhead-rated hardware, if you rig something that gets someone killed or maimed, you're going to see the inside of a courtroom. Not to mention that you've then got to suffer living with yourself afterward. Whether you're sued until you've no more assets to litigate after, or you go prison for negligence, you're going to get in trouble unless you can prove beyond a shadow of doubt someone else was at fault and if you can prove you were not at fault (you could still get in trouble for contributing to an accident, whether or not someone else was at fault for the immediate cause of that incident). Your argument about a technicality just changes the degree to which you are an easy target (and yes, if you rig something and someone gets hurt using your rigging, you're an easy target no matter the cause and no matter the technicality used in your defense).

 

[BillConnerFASTC]

I assure you it has been discussed at length with the people at Clancy, SECOA, and many, many others. You are correct that a court decision could change the original intent, but until that time, I feel on more solid ground using the term as the people who coined it say they intended.

It is simpler. Just find a chain manufacturer that will review the application and write a letter saying that their grade 30 or other non-alloy chain is recommended for it. Honestly and openly and with full disclosure. I can't. So much of it from many parties is based on partial or selectively edited statements, like the excerpt above you mention without the full text that contradicts the impression of the excerpt.

I'm not worried about grade 30 trim chains in use for the most part, including on systems I specified before I learned more. On new systems and on renovations when changing the lift lines, there is no reason not to comply. The cost of STC or Alpha is too little more than grade 30 to even consider otherwise.

 

[MNicolai]

Now's probably not a bad time to bring up PLASA's standards:

A.3.18.3.3(c) Trim chain assemblies shall be fabricated of chain approved by the manufacturer for the application. The wire rope eye termination shall pass through the end link of the chain. The chain shall be long
enough to wrap one and one-half times around the batten and return to connect at the eye termination
using a load-rated connection. The installed trim chain assembly shall have a breaking strength greater
than the breaking strength of the wire rope.

A.3.18.3.3(d) Any chain used in a single load path assembly shall be certified in writing by the chain manufacturer as suitable for the intended application.*

ANNEX A (This annex contains informative notes that are not part of the normative requirements of the standard.)
A.3.18.3.3 Wire rope terminations, paragraph (d)
The typical trim chain assembly described provides a multiple load path between the batten attachment
and the lift line. The intent of the section is to require either a) manufacturer’s certification that the chain is
rated for overhead lifting, in accordance with NACM definitions, or b) manufacturer’s certification that the
chain is suitable for the intended application if its material properties and strength characteristics do not
meet or exceed that of Grade 30 Proof Coil chain. As of the publication date of this standard, only Grade
80 or higher alloy chain is acceptable by the NACM for overhead lifting.

 

[Footer]

Personally I will be happy when my space has its lift lines terminated with something besides a clove hitch and a few cable clips... Grade 30, grade 80, whatever. It really surprises me that we spend this much time talking about and writing standards for this.

 

[MNicolai]

@BillConnerASTC and I were chatting via PM and he asked me specifically what my interpretation of "freely suspended" meant. I was originally going to PM it to him, but I felt instead I should post it here for the masses.

I believe I derived my interpretation from Clancy's white paper 3 or 4 years ago, but have recently been swayed from it by the information that's been presented. My understanding of the term is to mean that something is suspended in such a way where the sudden release of that lift line would release the load or cause it to destabilize and swing in such a way as to present risk of injury or harm to people below it. Per Clancy's explanation, I considered a batten to not fall into that category, as the entire assembly of the rigging for a given batten is such that if one lift line failed, the others would partially compensate for the failure. I also considered a freely suspended load to be one that was at risk of additional, significant dynamic loads due to an ability to swing around, which a batten is suspended such that it would not swing around wildly.

By that understanding, a speaker cluster suspended on one or two chains would be freely suspended. If one chain, then the failure of that chain drops the load. If two chains, then the failure of one chain likely precipitates a failure of the other, and even if it doesn't, the load center of gravity would suddenly shift in such a way as to turn the 1200lb load into a pendulum of death.

If that cluster is evenly suspended on four lift lines of chain though, each chain with a capacity of 7x that of the full load being lifted, then the failure of one chain, while precarious, does not send the entire load into a tailspin that drops the load or causes a pendulum effect that likely causes the rest of the chains to fail in a catastrophic domino effect.

Potentially the greatest flaw in that interpretation though is that its highly subjective. So much so that the only way to determine if a given design is safe, to more precision than someone's gut would tell them, is to run destructive simulations on potential methods of failure.

What we're talking about here for a facility with 36 linsets, 7 lift lines ea, is $2750 for G63 alloy trim chains, versus $750 for G30 trim chains. Before I got into consulting at my current position, I would've happily been the end user to say I want my $2000*, G30 is just fine. Now though, I'm far more apt to say, the extra $2000, aside from being the right and just thing to do, is a drop in the hat in the construction of a $15M theater. It's a lot different seeing the world from the eyes of a consultant. $2000 out of $15M is perfectly alright for helping me sleep better at night though.

*Those numbers were based off of prices I got from Sapsis' website. I'll bet there's even less of a difference, G30 versus G63 with a volume discount.

Bill's swayed me. The cost difference is negligible. Like him, I'm not compelled to go so far as to say G30 trim chains need be immediately gutted and replaced. I still think the language used by NACM and OSHA needs touching up though. That "freely suspended" phrase can really pivot the entire interpretation of what "overhead lifting" is, thereby undermining all regulations that reference overhead lifting.

 

[gafftapegreenia]

Personally I will be happy when my space has its lift lines terminated with something besides a clove hitch and a few cable clips... Grade 30, grade 80, whatever. It really surprises me that we spend this much time talking about and writing standards for this.

And I will be happy when my alma matter finally gets the last dog clips off its trim chairs. The things that were acceptable in 1975.


Sent from my iPhone using Tapatalk - now Free

 

[BillConnerFASTC]

NACM who I believe introduced the ter "freely suspended" said it simply meant the load was not restrained, because if it was even alloy chain might not be strong enough. Anchor the load to the floor and the chain might fail. I suggest when reading codes and standards don't try to find deep hidden meanings in the words.

 

[MNicolai]

Plot thickens on acceptability of G30 chain and if a manufacturer will endorse it for overhead applications. Seems CM shows this in their theatrical products catalog.

 

[BillConnerFASTC]

Are they the manufacturer of the chain or simply a re-seller? Now, I acknowledge that is not as easy as it sounds, as for instance SECOA's STC is manufactured for them by another company, but for the purposes of recommending it for the overhead lifting application, SECOA is the manufacturer. Similarly Clancy and Alpha Chain. (In the small world category, they are made in the same factory.) So I've seen this add but I also have heard engineers say grade 30 is OK for overhead lifting - but that doesn't change the fact the manufacturers say it isn't, and I don't want to ever have to defend going against a manufacturer.