Welding Wide Flange Splices 4

[sedonas]

When you weld two wide flange together by cutting them square... would it make sense to further strengthen the web by putting cover plates over the web? Or over the flange?The purpose of flange is for tension and compression.. the web is supposed to be only for shear? Which to focus more in welding.. But if you weld cover plates on the flange.. won't it weaken the flange by having many welded regions.. how do you weld your splices (that involves no bolted connection)?

 

[sedonas]

Thanks for all the basic. I've been reading AWS D1.1 too.

Gtaw. When you joined purlins to purlins of 1.6 to 1.8mm thickness. Do you use 6011 or 6013 electrode? Won't 6011 burn thru it.. and if you use 6013.. won't it be not enough to join the metals? We only have 6011 and 6013 available locally. Thank you.

 

[vhengr]

For joining Purlins/girts of such thin cold-rolled sheets bolted lap joint is generally preferred.

If welding is the choice then to gor MIG welding rather.

Best Regards_ VH

 

[sedonas]

We don't have this technology called MIG (Metal Inert Gas) welding and lack of availability of bolts designer.

We only have SMAW (Shield Metal Arc Welding) technology and 6011/6013 electrodes. There must be a way to weld 2 pieces of 1.6 to 1.8mm purlins. Do you fillet weld this? Won't the welding holds if done properly? A structural engineer said the 6011 is too powerful for it.. he only suggests 6013. We will have new group of welders for this job. The old welders can't be found anymore. They ran away already. So before we pay the new welders. We want to make sure they welded the purlins right. Thank you.

 

[vhengr]

For cold-Rolled purlins members; standard bolted Lap details may available with purlin manufacturer catalogue.

Welding of such small thickness sheet with stick is rather difficult than Wild flange sections welding and may reqd more skill-sets!

Best Regards_ VH

 

[sedonas]

Our purlins came from china.. we never use bolt laps.. no one here uses it so it would even be more immensely difficult.

We really only have SMAW and 6013. What skill sets must be observed. They already have the welding machines and electrodes and purlins delivered in site. They will start welding tomorrow. One local structural engineer said it must be stitch weld.. that thin sections will just tear if bolts are used.. to be sure.. we will weld every surface (stitch weld).. 6011 is too powerful and should be avoided? The 6013 is the only one available. It should be enough to melt the metal and connect them on atomic level. Please share techniques so I can see to it the new welder follows it tomorrow and for next 2 days. Thanks.

 

[sedonas]

For cold-Rolled purlins members; standard bolted Lap details may available with purlin manufacturer catalogue.

Welding of such small thickness sheet with stick is rather difficult than Wild flange sections welding and may reqd more skill-sets!

Best Regards_ VH

The senior structural engineer advised against bolted purlins because he said they can tear especially if there is movement in the frame.. therefore welded purlins are advised.. anyway can you show pictures of any bolted connected purlins? Maybe they are not for seismic.

The welded parts are more ductile and can move. He advised using stitch weld with the electrode 6013 in SMAW..

But since he is not welding expert.. never personally weld.. I'd like to hear from gtaw or others who have welded hot rolled thin sheet 1.6mm to 1.7mm the best way to stitch weld or what to watch out.. thanks in advance.

 

[andriver]

I did not read every post, but those are the worst welds I have EVER seen. Everything about it is terrible.

 

[sedonas]

The senior structural engineer said we never use bolts on purlins. That all the hundreds of billboards in the streets don't use bolts but welded. Reviewing the old welding jobs. I realized all the purlins were spliced welded like the following:

Searching in the net for bolted pulins. I found this:

But these are Z purlins and they are coated. Our purlins were bare steel without coating.

What is the best way to ensure the 1.8mm spliced purlins will have welds that fully combined them in the atomic level (or complete weld)? Should 6011 or 6013 be used?

In our country. Designers don't give any details about weldings because they said their job is not welding (they don't know how). So it is the job of the welders to make it right (or wrong). In the structural plans. There were no mentioning of what kind of welding.

 

[sedonas]

Our designers are one of the biggest in the country:

http://www.rbsanchez.net/

But they are not familiar about welding.. saying it's up to contractor to do it right. But my old contractor has already ran away. They just hired welding subcontractor who don't even own any welding machines because they can't afford it. In our country. 99.5% of welders don't own any welding machine.

This is the reason I can't do any edging test kingnero suggested.

Just tell me. Will 6011 or 6013 achieve full fusion of the 1.8mm thick purlins to be spliced? I'm reading the AWS D1.1 but can't find it. Please give a tip or two more... esp. gtaw.. many thanks!

 

[gtaw]

What is the material specification of the structural members?

If they are ASTM A36 (or the equivalent), they can be welded with E60XX electrodes, but the thicker the material, the more preheat is required to mitigate the possibility of hydrogen cracking. AWS D1.1 allows ASTM A36 to be welded with E60XX electrode (E6010, E6011, E6012, E6013, etc.) up to a thickness of 3/4 inch (about 18 mm). One can weld thicker sections, but the possibility of hydrogen cracking increases slightly and higher preheat should be used.

E60XX isn't recommended on ASTM A992 wide flange members because of the higher strength, i.e., 65 ksi) and higher carbon equivalency. That isn't to say it can't be done, there is simply increased risk.

Best regards - Al

 

[sedonas]

Material Specification is "A36 and SS400". From our supplier..

http://www.reganindustrial.com/home.php?pg=sections

What do you think about SS400?

See

http://www.meadinfo.org/2010/09/jis-g-3101-ss400-steel-properties-spec.html?m=1

I dont know if it means combination of A36 and SS400 alloy or either only?

For you stitch weld is same as fillet weld isnt it

So 1.8mm thickness vs 10mm thickness weld is controlled by the current. I talked with the new welder now he said 6011 can be used on 1.8mm thick purlins by controlling the current. He is not metallurgist but jus ordinary welder who earns $15 working 10 hrs so need opinion and experience of others abt 6011 on thin sections. Tnx

 

[gtaw]

It would appear they are equivalent.

An intermittent fillet weld is called a stich weld by those individuals that are unfamiliar to standard AWS terminology. A stitch weld is "slang" or non standard term for an intermittent fillet weld.

E6010 or E6011 would provide a more aggressive, penetrating arc than E6013, but all three have the same minimum tensile strength if the weld is properly deposited. With the aggressive penetrating arc there is the potential for increased levels of diffusible hydrogen. However, on 18 mm thick low carbon steel, it should not be an issue if the minimum preheat (say 40 degrees C) is maintained.

Best regards - Al

 

[sedonas]

Gtaw i was NOT referring to 18mm. But thin 1.8mm section

So 1.8mm thickness vs 10mm thickness weld is controlled by the current. I talked with the new welder now he said 6011 can be used on 1.8mm thick purlins by controlling the current. He is not metallurgist but jus ordinary welder who earns $15 working 10 hrs so need opinion and experience of others abt 6011 on thin sections. Tnx

Post Edited

 

[gtaw]

OK, I missed the fact that we changed gears and now we are solving a different problem.

Yes, the welder can weld the thinner purlin with E6010, but for the thin material, the E6013 would be a better choice because it is better suited for thin material.

Best regards - Al

 

[sedonas]

gtaw.. I wonder if you agree with this web info about the difference between weld fusion and weld penetration.

http://www.lincolnelectric.com/en-u...heory/Pages/weld-fusion-weld-penetration.aspx

"Theoretically (but not realistically), you could even have complete fusion to just the depth of a few molecules and still have welded the pieces together."

So the trick in thin metal welding is enough weld fusion to molecularly combine the purlin to purlin.

But why did some believe you need Metal Inert Gas (MIG) welding for thin section.. like they believe Shielded Metal Arc Welding is not even possible or so hard. For you. Do you use MIG or SMAW in thin section (1.8mm purlins) and why?

 

[moltenmetal]

Someone without the skill to butt weld together 10mm thick sections of carbon steel with a stick (SMAW) welder, will not be successful butt welding a 1.8 mm thick member. They will melt through and make a big mess. If you can lap the two pieces over one another and deposit a fillet on both sides of the joint, they might have a hope.

I am not a welder whatsoever, but even I can successfully weld material less than 1 mm thick using "hard wire" metal-inert gas (MIG). I can even manage reasonably well using flux-core MIG, though the welds look terrible and need a lot of clean-up.

 

[sedonas]

In our place. We don't use MIG because it is heavier and it can explode.. note our welders don't wear any protective gear.. they only use clothes to cover their face and broken shades because they can't afford any protective gear (imagine those ISIS in Syria figure doing welding).. remember our welders never own any welding machine because they can't afford it so they use their contractor machines. Hence the difficuly of any edging test because of 2 unwilling participants.

Anyway. Whatever is the repair of the wide flange splice.. we need to reinforce it... so we will support the entire wide flange with vertical C-section beam every 2 feet (to carry 42 lbs of weight.. it's w8x21 meaning 21 lbs per foot). The vertical Cee section (called purlin if horizontally) is about 1.7mm thick and we will attached it to the top of the wide flange every 2 feet. The wide flange is originally to brace the cladding wall below but we redesigned it to carry the wide flange above which will have no load anymore because of the weak splice (it's supposed to carry another wall).

So what's the best technique you guys experience to weld thin section to thick section? Imagine 1.7mm vertical Cee section braced to wide flange top flange using 4.5mm x 2 inches angle bar brace.

Earlier we talked about welding thick section to thick section, then thin section to thin section.. now thin section to thick section. The AWS D1.1 is a cookbook but we need seasoned welders to share their unique experiences using Shielded Metal Arc Welding (the only one we have). So should 6011 or 6013 be used? Gtaw? Thanks.

 

[gtaw]

E6013 using AC is intended for "thin" base metal. It does not penetrate the base metal to the same extent as E6010 or E6011.

I believe E6013 would work fine is the welder had time to practice and develop the technique. I would suggest using 3/32 inch diameter (5 mm) electrode for the thickness your working with.

Best regards - Al

 

[sedonas]

Gtaw. We changed gears 2 messages ago and solving a third problem.. that is welding thin to thick metal or 1.7mm purlins (Cee section) to 10mm wide flange flange. You are saying that whenever there is thin section mixed with thicked section. one must use 6013 and treat the thick section as thin one by aiming for just enough weld to make the two atoms mixed or just enough weld fusion (edit: i meant weld penetration) equal to the thin metal thickness or 1.7mm on the 10mm thick material?

 

[sedonas]

Here's pic of my new welder welding the 1.7mm vertical Cee section (purlins) to a 4.5mm angular 3x3".

I gave him the 6013 3/32 electrode.. but he told me a while ago it takes too long to weld.. he wants bigger one.. should I give him larger version of 6013 (what is it) or should I give him a 6011?

Remember he is just a welder.. been welding for dozens of years.. this is what the welders in our country looks like. He is not metallurgist so let's analyze the interaction of the welds at the molecular level.