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Up Topic Welding Industry / General Welding Discussion / Welding ASTM A9 to A36
- - By yojimbo (***) Date 06-28-2017 00:00
Doing some leg work for a GC.  Project requires splicing new base plate/fabricated column assembly into existing ASTM A9 steel columns.  PE has provided joint/splice fabrication drawings which call CJP welds at the different base metal conjuncture.  Structural notes call out WPS per AWS D1.1, Clause 4, which means they know what they are doing but makes me wonder if they really know what they are doing.  Not too much info on ASTM A9 that I've found; not used for a long time, was the building steel of the earlier 20th Century, lower yield/tensile, not a pre qualified base metal, some sites indicating poor weldability.

Anyone qualified a WPS for ASTM A9?  Any pointers?  CJP without backing is required.  6010 root/7018 on out?  Pre/post heat?  Final inspection criteria not listed in Contract Documents AFAIK.  Backing material could be a possibility with engineers approval/demonstrated necessity.

Thanks in advance.
Parent - - By 803056 (*****) Date 06-28-2017 02:20
Early steels were not intended for welding. They were bolted or riveted. The chemistry can vary considerably heat to heat, i.e., piece to piece. They did not control C, S, or P; delayed cold cracking can be a problem when the carbon is on the high side. Hot cracking can be a problem when the S or P is greater than 0.04%. 

A quick weldability test is the fillet break test performed on the actual member. Weld a 1/2 inch thick plate (4 x 4) with a single pass fillet weld. 1/4 inch or 5/16 inch leg should suffice. Then hit the plate several times with a sledge to see if the welds break through the fillet weld (good results) and shows good ductility. If the weld breaks easily, pulls out of the base metal, acts as if it is brittle, i.e., takes few hammer blows to fracture, you can expect problems with that particular piece of steel.

Regardless, higher than normal preheat with E7018-H4R is a good way to proceed. NO E6010! Qualifying the WPS is meaningless because the chemistry of each member can vary considerably.

As the engineer, I would require each weld to pass UT after a 72 hours dwell time. The delay is to allow delayed cold cracks time to incubate and propagate if there is going to be a problem with hydrogen assisted cracking. Stringer beads (limited heat input)  are recommended to mitigate problems caused by S and P. If the base metal is thick, use a butter layer (two layers) technique against the base metal and then switch to a limited weave to temper the butter layers.

Good luck - Al
Parent - - By welderbrent (*****) Date 06-28-2017 03:35
Take more than luck on that one, about 40 days of fasting infused with 24 hr per day prayer. 

Would it not be more feasible to bolt A36 or A572-50 plates to the existing column members and then weld to that?  A good mag drill with roto broach bits would make quick work of the holes. 

I would be pretty cautious about welding to those. 

He Is In Control, Have a Great Day,  Brent
Parent - - By 803056 (*****) Date 06-28-2017 13:08
Brent, I like your approach if it is viable in this case. I like to know what my chemistry is before striking the arc. It is probably cost prohibitive to perform a chemical test on each member depending on how many are slated for welding. However, that is the best way one can make a fair and reasonable decision on the weldability of the material.

I would not recommend using a PMI gun due their limited ability to determine carbon, sulfur, and phosphorus content. A true chemical analysis is required which would require sending a piece to a good laboratory.

I had a recent experience with a chemical analysis of a steel casting using PMI. I didn't trust the values I was told and insisted on a chemical analysis. There was a significant difference in the carbon content determined by each method. Had I gone with the PMI value, I would have been in serious trouble.

Al
Parent - - By yojimbo (***) Date 06-28-2017 15:31
Gentlemen,

Thank you for your replies, they confirm my suspicions based on limited knowledge/research and my original decision not to get involved with this project at bid.  The structure is an historical pergola being refurbished and relocated to a tourist waterfront.  The GC is asking me to take another look at providing some misc. steel for the job, part of which are the base plates/column extensions they plan to splice into the original columns.  I'd told him there was too much complexity and logistics to coordinate with other trades and the contract documents weren't really up to adequate detail but he responded it didn't seem complex to him at all.  And that was before the A9 chemstry and weldability issue was even broached.  Read yesterday about the necessity of doing chemistry samples and wondered how the smart money was planning to do that along with the fact the chemistry was so uncontrolled in the base metal it could vary in each section.  And with the CJP requirement, qualifying a procedure would men a multitude of tests and where are you going to find a piece of A9 for the coupons?  I understand a GC not understanding the details of this issue, but there were ACTUAL ENGINEERS who drew up the 1.5 million dollar taxpayer funded boondogle.  Of course, with billionaires now being the standard of citizenship, whats a million or two hard earned revenues being smoked.  I suppose it's allowance money for some.  I guess it's back to the salt mines for me.
Parent - - By 803056 (*****) Date 06-28-2017 19:34 Edited 06-28-2017 23:35
It isn't a matter of qualifying a procedure.

There are some jobs you walk away from or quote them time an material. Put a CYA clause stating clearly you recommend not welding to the A9, but will do it under the direction of the Engineer. Put the ball in the Engineer's court and ask him to provide the WPS he wants you to follow and then make darn sure you do exactly what it says.

I develop a lot of WPSs for the Engineer to provide specific direction to the contractor performing the work. In many cases I oversee the work to make sure the contractor does what I tell him to do. In those case, I reserve the right to fire a welder that isn't following the WPS to the letter. It happens on nearly every project involving a new contractor. One welder knows more than anyone else and i have to run him off with him paycheck in my hand. I can't recount how many times I've heard, "You can't fire me, I don't work for you!" Surprise!

Al
Parent - By yojimbo (***) Date 06-29-2017 03:33
How is not a matter of developing a procedure when the Contract Documents specify the welding must be done to AWS D1.1 Clause 4, which, correct me if I am wrong, is the clause directing the qualifications of procedures?

I didn't bid this project; it bid awhile back and I looked at it.  There were too many other CD discrepancies for me to pursue it.  The whole A9 issue hadn't been explored but my gut told me just looking at it there was a big problem.  Probably something about knowing there was a lot of cast material involved with other portions of the work, the historic nature of the structure, the agencies that were promoting and getting it funded, the lack of critical detail in the drawings.  Just been working with the GC who did win the bid on other gigs, and he's got some holes in his spreadsheet for misc. steel supply he needs filled.  When I got to the A9 issue I gave him the heads up that's he's in for stormy weather.  I try to stay out of the field welding these day as much as possible.  Hard to admit it after a career of just that, but it takes more of a toll these days so I stick pretty much to what I can produce in the shop and will field weld/install my stuff but let the rest of it go.  Sucks getting old- It ain't for sissies.

Hey, if you can develop a procedure for this stuff let me know and I'll pass it on to the GC.  Good guy and he's gonna need it cause I sure as hell ain't touching it with a 20' stinger.
Parent - By 803056 (*****) Date 06-28-2017 23:49
I like the part, "If a suitable procedure can be found,...."
Parent - By yojimbo (***) Date 06-29-2017 03:35
Thanks Fred.  I'll give this a read and pass it on to the ones with the headache.
Parent - - By kcd616 (***) Date 06-29-2017 07:09
Brent,
we almost agree:eek::twisted::yell::wink::surprised:
"Would it not be more feasible to bolt A36 or A572-50 plates to the existing column members and then weld to that?  A good mag drill with roto broach bits would make quick work of the holes."
I would use an ironworker and punch the holes, and do it quicker
but just imho
sincerely,
Kent
btw my best to you and yours on this fire, thinking about you my friend :smile::yell:
Parent - By welderbrent (*****) Date 06-29-2017 15:04
Ironworker for the holes in the plates yes, but not for the ones in the existing columns and/or beams.  Mag drill.  Can even use vertical or upside down.  Just remember to secure it in case you push so hard that you break the connection and the drill comes tumbling down. 

Fire issue is looking better thanks to much Divine intervention.  Winds have died down, cooler temps today, fire shifted course enough to take it into lower density population areas.  More people on the fire line, about 750 now.  I think we are about to turn the tide and get things under control.

Thanks to all for your thoughts, well wishes and prayers (in which I firmly believe). 

Brent and family
Parent - By Horence Date 08-01-2017 05:53
After reading the whole post, I have learned more about this topic. Thank you so much.
Up Topic Welding Industry / General Welding Discussion / Welding ASTM A9 to A36

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