Smooth Operator
It would depend on what product you are building and what your contract specifications say. Just because a product MTR doesn't get rejected right away, doesn't mean it won't get rejected a year or two later. If GR. 50 weathering steel was specified, and you requested just grade 50, you could get A-572 Gr 50.
Many crooked contractors are lucky that they don't get caught. Many inexperienced contractors do not know the differences, and get what the helpful salesman will send to them. Some get caught some don't.
Sometimes, you can ask for the right product and even specify it correctly, and the service center will send you the wrong product. I have seen this quite frequently, even recently on a NYCDOT project! I am a third party inspector, and I review MTRs when I receive them. I also reconcile the MTRs to the material as it is received or when used in the fabricator's plant.
I have been tripped up by what I call "mislabeled" MTRs and products. I once was caught up with a product labeled "A-36 M-53". I did not yet check the MTR, when the State DOT called me back after hours and asked me why this material had an 83000 UTS? (80000 is the UTS maximum for ASTM A-36) (I also thought that the M-53 was an AASHTO number!) I called the mill the next day and asked why I had a sworn MTR with an error like this. Suddenly, I was on the defensive. The mill wanted to know how I got hold of that material, since it wasn't an ASTM material, it was "A36 M53" which was a "Lukens Fineline Steel" proprietary product not sold to the general public! This product was stolen! Well I had ordered it through the steel service center, and that is what they sent me. I was lucky that fabrication was delayed, or there would have been yards of concrete poured over the pieces fabricated form that steel!
Other times I was not so lucky. Bayou Steel gave me improperly labeled product once. It was listed with an ASTM A____/ M. When I caught it, I thought the "M" meant metric, (like it shows on the ASTM Standad Specification). But, No! This "M" stood for "Modified". I complained that they should not have labeled it as an ASTM___, if the "M" didn't mean metric. When I called them on it, I was told "FU! If you don't like the way we do things don't buy from us!" Once a company I worked for ordered "Made and Melted in the USA", and received "Made in Canada" angles. No one caught the Made in Canada until the final welded product went out to American Bridge. Then the S**t began to roll back down hill! Hell, if I wanted to cheat, I would have at least ground the "Made in Canada" off! We were covered by a Purchase order, and an incorrect MTR. The system failed in receiving inspection, during my QC inspection and by final inspection by the State QA inspector! Big egg on everyones face! Another time I ordered circles cut from A-588 Gr.50. When it was delivered with the MTR, (which showed that it all came from the same plate), I noted that three of the circles had red mill scale and three had blue mill scale! The Steel service center was pulling a fast one! When I found a stamped serial/heat number in one of the corner drops, that didn't reconcile with the MTR, I rejected the whole lot.
You should get the ASTM Specifications and make sure that you specify exactly what your contract requirements demand on your purchase order!
Joe Kane
JK Thanks for the heads up. Usually the specs. and our approved drawings have an ASTM#/GR50 and I notice some of our pieces have A-572, A-588, etc. stamped on them when they come from the warehouse, usually don't get everything in same number. Another question ,been getting alot of bigger sized shapes ( c12 thru c18 and wf's 12 thru 24's) salesman from warehouse claims everything in these sizes is being run as duall cert. from the mills because of "operating costs" do you know anything about this? ( sounds like B.S. to me). " AMERICAN BRIDGE LARGEST STEEL FABRICATION PLANT IN THE WORLD " circa. 1950 plant sign by USS at plant main gate over RT.65 ,had the town named after it because it was so important to local economy. Now privately owned an moved across river ,had a few contracts when they were building new plant. A mere shell of it's former greatness. Sad how some things change and will never be grand again. PS GO STEELERS AND PENS
Smooth Operator
Most material has been run as dual cert material since the early fifties. (I am told! It was before my time of interest in Steel!) I find it amazing that many people (including leading engineers and professors,) don't know this! This is done whenever the overlap in chemistry and mechanical properties make it possible. In many cases testing for properties and chemistry is done several times so that they can get a report that gives them the required overlap in chemistry and property. That is one reason that Lo-HY electrodes should always be used. Years ago the NYSDOT required that steel bridge beams be ASTM A-36 only. To get that material, you had to pay 2 or 3 cents per pound extra. There is a rather incestuous relationship between the ASTM Committee membership and the Steel Makers.
Yes, one time American Bridge was the biggest and most technically advanced bridge fabricator in the world.
Smooth Operator,
Joe is right in what he's been telling you. Regarding structural beams, much of it is being rolled to comply with A992 now, which was simply the old A572/Grade 50 modified to "Technical Bulletin 3". That was "adopted" by ASTM as A992.
Much of the steel rolled today is melted from scrap with other materials added to get the right recipe. Because of that steel will now easily meet A992; A572-50; A709-50; and M270-50 specifications. Those are all essentially the same stuff although there are some subtle differences between those specifications requirements.
Since A36 chemical and mechanical requirements overlap with A572-50 requirements, it is very common to see steel certified to multiple specifications. It is possible that you could see the same piece of steel multiple-certified to A36; A709-36; M270-36; A572-50; A529-50; A709-50; M270-50; A992, as well as various ABS grades and who knows what else.
Now if have that all straightened out consider this: A1011 coil is frequently being used to produce structural plate. I won't go into the fun that is.
One disturbing trend I have seen is the reluctance of engineers to do the research needed to understand all of this. We recently had a "fun time" trying to explain why the A709-50 material we had was, in all respects, the equivalent of M270-50 that was spec'd out. Long story shortened: the engineer had to accept a long delay in getting a mill rolling when he could have had perfectly good materials in fabrication immediately. (But in the end it didn't matter - everything is the fabricator's fault anyway- I think that's in standard contract terms & conditions.)
Joe P Kane,
Thank you for your reply, currently I am on vacation and I don't have any of the books at home. I do have a four volume set of AASHTO manuals and I have the 2006 edition of M270.
A supplier did provide me a MTR for A709 and I compared the alloying values against the M270, and sure enough the Mn value is tighter for M270 than A709.
This is from memory but I believe M270 said the highest Mn could be was 1.25 and per a footnote could go up to 1.35, but the MTR I was given had a Mn value of 1.43 so I told purchasing that it was out of my value and not to purchase that plate.
I'll try to keep checking even though I don't want to think about work while at home.
Chris
You need to re-check your specs. Chemistry requirements for AASHTO M 270 and ASTM A 709 are identical. In both, the stated max Mn is 1.35, but per footnote can go up to 1.60%. There was nothing wrong with your plate.
In general, M 270 is A 709, maybe behind a version or two because ASTM ballots several times a year but AASHTO only once, and AASHTO doesn't do anything to M 270 until after ASTM makes its changes to A 709. However, contracts are contracts, so if your contract calls for M 270 and your MTR says A 709, just get the mill to issue a different one with exactly the same numbers but the words "AASHTO M 270" on it. Or get your customer to agree they're the same and accept the MTR you have; if they have any clue about steel standards, they will.
Hg
HgTX,
I believe that he stated he had the 06 manual. In that edition your Mg 1.35 but allowed to be 1.5 with carbon reduction. In the current edition you are allowed 1.6 with 20 to 1 limit for sulfur. So this would be dependent on edition of spec listed in the contract.
The 2006 editions of both had max 1.35, up to 1.50%. That 1.50% got raised to 1.60% in both specs in 2007. Either way, 1.43% was fine (unless he ran into the sulfur ratio restriction, but from his post I don't think that was the basis for the rejection).
And one can't compare entirely different editions and then say the two specs aren't equivalent. The AASHTO spec very clearly states which edition of the ASTM spec it is equivalent to (typically a year behind, sometimes not, sometimes two years). Right now they're identical except for the Charpy tables, because of some confusion during balloting; that's supposed to be rectified in the next edition of M 270.
Other than one version lagging slightly behind the other because of balloting timetables, there have not been chemistry differences between M 270 and A 709 for a very long time (decades). For that matter, there have not been *any* differences for a very long time; there was a PERCEPTION that the Charpy requirements were different because of how the two specs were structured, but they have since been rearranged to eliminate that confusion.
Hg
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