The following article excerpt from Modern Steel Magazine from AISC describes the advancement of steel designations. This is part of a 3 part series of articles titled 'Are You Properly Specifying Materials?'
"So what is “ASTM A572 grade 50 with special requirements per AISC
Technical Bulletin #3, dated March 1997” anyway?
In the early 90s, wide-flange steel producers began a practice called dual-certification, targeting
their production of wide-flange material for the window of overlap between the
mechanical, chemical and other requirements in both ASTM A36 and A572 grade 50. Among
other factors, the lack of an upper limit on yield strength in ASTM A36 made this possible.
Steel producers benefited because the resulting product could be stocked universally and
sold as either A36 or A572 grade 50. The consumer benefited because price differentials
between ASTM A572 grade 50 and A36 quickly eroded. Alas, there was often confusion
about the product being supplied because it usually carried both names.
To eliminate confusion and facilitate the shift to a single grade material for wide-flange
shapes, AISC proposed the material specification “ASTM A572 grade 50 with special
requirements per AISC Technical Bulletin #3, dated March 1997” Since that time, it has been
approved by ASTM as specification A992.
Note however, that ASTM A992 has not yet been incorporated into all industry documents,
including AWS D1.1. Thus, to avoid the otherwise unnecessary project-specific qualification
of ASTM A992 material for welding, call it by its longer name in this interim period
until the codes catch up."
This was in 1997. The article was published in 1999. By the early 21st century there were more changes under way and not just among wide flange shapes. They were working on all shapes.
Why? About this time was when 'Green' and 'Lean' manufacturing was coming into it's own. Not to mention the bottom dollar: PROFITS. The steel mills were trying to find cheaper, faster, leaner, greener methods of cutting costs.
One way, reduce the multitude of steel designations where you can make them overlap and incorporate many into one. In some cases this meant assigning new numbers to a new product that covered all previous specifications involved.
A casual glance at MTR's for most any product will reveal multiple designations. Angle iron that meets A-36, 709-50, 572-50, and/or 529-50. Not necessarily all of them, but often most of them. The same for plates: A572-50 and 709-50.
And according to other articles it appears that the mills are actually phasing out the A-36 designation in many, if not all, shapes. The new products and specs meet the customer demand better and still cover anything previously accomplished by using A-36. As it is almost impossible to locate a pure A-36 Wide Flange beam, it will soon be of other shapes.
Now, JT, this is not to refute you or anything of the like. I wanted to leave that other thread as clean as possible for the OP. I also just wanted to show where my information was coming from.
You made another comment that is very good, about locating certain steels. It has to do with the size of the local steel supplier and where they get their product. If a fabricator or supplier is ordering straight from a mill they are more likely to be getting the newer numbers and having problems getting the ones being phased out. But, if they have their own warehouses and supplies that are older that they are still drawing from then they are trying to get rid of the old before restocking with the new. It mainly revolves around costs/profits. But there are other factors as well.
So the variations in what is available will have a lot to do with your geographical location, your supplier and their upchain, and the product itself, and, as you mentioned, the volume the customer requires for their job. One piece, one truck load, or one train load. It all makes a difference.
One must be careful in this ever changing industry of making dogmatic, all inclusive statements. I don't believe either of us did. We both stated things we had witnessed. This is just info to show what appears to me to be the direction that steel specifications are headed. It will be ever more important to verify with the engineer that the steel available meets the requirements of the job being done. And keep as updated of a list of ASTM Standards as possible on hand. Not to mention all the other codes we each work to. They occasionally will include items before a new ASTM book comes out. But the specs are available from AISC or ASTM in printable format to add to your collection.
Hope all find this informative. Just my two tin pennies worth.
Have a Great Day, Brent
I have all three parts in my library. Excellent articles. I remember years ago when dual cert wide flange beams were a not common item. In my past experience, they used to be pretty much A36. If we needed A572 gr 50, it had to be specially ordered. Back then we did mill purchases from Bethlehem Steel in Pennsylvania, and we'd back haul loads from Bethlehem to our plant after our drivers made their deliveries to various job sites up north.
Later on we started seeing dual certs. (A36/A572 gr 50), and eventually tri certs. (A36/A572 gr 50/A992). Before we started seeing MTR's with dual certs., if we needed an A572 gr 50 beam or two on a job (back then they weren't specified very often for the structural work that we did), rather than special order them, I'd go through the MTR's and find some A36 beams that we had in stock that met the minimum yield and tensile properties of A572 gr 50. I'd submit the MTR's to the EOR, and the substitution would always be approved. I was also able to do the same thing on A36 sheets of plate and flatbar when A572 gr 50 was specified.
The old term for A572 Gr 50 back in the day was V50. Every time a 50 ksi material was talked about throughout our shop, at my previous employer, it was always referred to as V50 and had green and yellow markings from the mill on the cut end.
The good old days, when the engineer actually calculated things and used common sense instead of depending totally on a computer.
But, to be fair, manufacturing process control being what it is today, MTR's are usually in ranges to include a whole run or more of material. Back then they tested a lot more samples and the MTR matched shorter runs and was probably more accurate in many respects.
Have a Great Day, Brent
These days, they even send out representative MTRs vs an actual MTR on the product.
John, do your guys still use color coding for V50? Although ASTM removed the color code requirement for structural steel several years ago, our plant still uses a green and yellow stripe for V50.
A few years ago, with the release of the 2005 COSP the AISC relaxed it's MTR requirements and we took advantage of it. Since then, we keep representative MTR's on file for shop standard materials, as opposed to actual MTR's. I wrote a letter that we've been sending to EOR's on every project, that explains the 05 requirements, how we identify shop standard materials, materials other than shop standard, and materials ordered per an ASTM supplement. I also explain what a representative MTR means, so that there's no assumption that we're maintaining actual MTR's. If the EOR requires matching MTR's, I ask that he let's us know. We've not had any issues with this so far, and the auditors have liked what we're doing.
They aren't my guys any longer...I've moved across town to an Engineering firm as their CWI.
To answer your question about the green/yellow stripes for V50: My previous employer would have the detail material guys and the receiving foreman, when they received material in the door, write with a paint stick "572/50" or "V50" on anything that we would consider as stock(material not purchased for a specific project)..ie flats, angles, etc...
All of the materials that came in and were received for a specific project already had this information on a tag/sticker attached to the material. If it was a bundle and only one tag/sticker, they would then write it on each piece once the bands were broken on the bundle.
I think that part of the reason that A36 is stronger than in days past is due to recycling and not being able to separate the scrap to get out the higher strength steels and the strengths gradually creeped up to where it is today.
I just thought that maybe they just increased the carbon content to give it more strength. I didn't think about the scrap aspect of it, and that's my FINAL ANSWER.
LOL...good answer
That is part of the 'green' aspect, incorporating scrap steel into the product anymore. They actually guarantee a percentage and deem it a good thing for the environment. Sells more product.
Have a Great Day, Brent
The thing to remember with ASTM A992 is that it has controls imposed to limit the carbon equivalency at the mill and only low hydrogen SMAW electrode or low hydrogen welding processes are permitted. The latter is often overlooked by the fabricator and the erector because of the misconception that it is "just like ASTM A36." My response to that is, "No it ain't just like your A36. It is a different animal."
Al
