welding two plates together to fabricate structural angle

[welllily]

Hello,
Can anyone tell me if welding two plates together to produce a structural angle member would give me the same properties as a rolled structural angle? I have a situation where L250x250 is required in the design, but here in North America, L angles don't come in those sizes. The manufacturer propses to fabrical the angle with two steel plats with welding in the middle. Is this a good substitute for and actual rolled angle?

Thanks.

 

[SteelPE]

Are you looking for an L10x10?

I don't see why you couldn't weld two plates together to form the angle you are looking for..... although I think it would be a huge PITA to do. What type of weld are they proposing? I don't think I would be comfortable with a fillet weld as they would only be able to get the fillet weld on one side only. Some sort of PJP or CJP would be required.

Could the fabricator possibly import the section you are looking for?

 

[welllily]

Yes, L10x10. They are proposing to do a butt joint single V groove weld between two plates. I'm sorry, I am new to this forum... what is PJP or CJP? Yes, the slower alternative is importing the section from India.

 

[SteelPE]

PJP would be partial joint penetration and CJP would be complete joint penetration. It sounds like they are proposing a partial joint penetration weld. What is the angle thickness and what are they proposing for the depth of the single grove and are they proposing a continuous single grove or an intermittent single grove? One other thing that may be of concern.... if the fabricator is not careful this thing will look like a banana when they are done.

 

[TLHS]

Depending on what I'm using it for and what size plate it is, I'd probably prefer a bent plate.

 

[welllily]

the thickness of these plates are 1" and 1.5". They have not specified the depth of the single groove. The fabricator claims to have done this for other companies in the past, supposedly they know what they are doing. My concern is that in theory, this may work - welding two plates together to make up an angle; but in practice, can they do a good enough job to produce an angle by doing this? What tests is required to ensure that the quality of the weld is good, and what tests is requied to state that the end product is the same as a rolled L10x10?

By the way, thank you so much for answering my questions.

 

[SteelPE]

If they are proposing a complete joint penetration continuous weld I may not be too worried about it. However if they are proposing a partial joint penetration weld or an intermittent weld (CJP or PJP) you may have a little more work to do. You would need to calculate the force in the weld and make sure the weld can resist those loads. Only you will be able to do this as only you know the force you are trying to drive through the angle.

One last thing I would be a little worried about is what type of loads you are driving through the angle/weld. I have always been told not to load welds in bending....... so I would try to avoid this if I could.

 

[dik]

Generally a CJP weld would not be required for this... Distortion will be a real issue... in particular if the lengths are large.

using intermittent welds may be a lot easier and less costly.

Dik

 

[TLHS]

SteelPE, I don't see why you'd have a problem loading a CJP weld in bending. Fillet welds, it's generally a bad idea and I could see some groove geometry maybe causing problems, but if you're at the point where you're fusing the whole depth I'm not sure what the issue could be.

Out of curiousity, what the heck are you using a 1.5" leg thickness angle for?

If they're doing a full penetration weld, then I'd have no problem designing it like an angle for most load cases. In some odd cases, I might worry. You might get stress concentrations because you don't have the nice radius in the inside of the joint, so fatigue or some moment loads across that joint might take some though. However, if it's a long full penetration weld, it becomes a question of whether they'll actually do a good job with the distortion issues that will inevitably crop up.

If they're doing a partial pen weld then it depends on what you're using it for. If you're using it as a beam in bending you can probably make that work if designed properly. If you're cantilevering off the leg or something, as you might if you're using it as a connecting element, lintel or something of that sort then your peak stress is at that connection and you'll likely have trouble making it work.

Another option is to continue one of your legs past the joint so you can put a fillet weld on both sides. You may be talking pretty large fillets though if you're replacing a CJP of that size.

 

[dhengr]

welllily:
The fabed angle and the rolled angle have slightly different section properties, due to the lack of the radius’ at the toes and the lack of the large radius at the inside btwn. the legs. Otherwise, they can be assumed to be pretty much the same. You really have to explain more about your structure: the length of the angles, how they are loaded and supported, the magnitude and location of loads, how they will load the welded joint, etc. etc. You need to know and understand all of these things to make a determination of how the joint should be designed and welded. I doubt the a CJP weld will be required, they are very expensive to do, and just add to the potential distortion problem. But, you don’t want bending or tension stresses across the root of any weld either.

Depending on the conditions you are dealing with, I would first try offsetting the plates at the heel, so I could get fillet welds on the inside and outside at the point/joint where they join. For the 1" thk. mat’l, the vert. leg plate would be 9" wide and sit atop the horiz. leg. The horiz. leg pl. would be 9.5", leaving .5" of the edge of the vert. pl. exposed for the outside fillet weld. The welds would be sized according to need.

 

[SteelPE]

TLHS

This is something I have been told on a consistent basis. My interpretation of the intent may be slightly off but this is something that I still try to avoid if possible. Just last week I was at a seminar where the speaker went over the welding of your typical moment connection. In this instance the weld was subjected to both tensile and bending loads at the same time an failed pretty quickly (this is probably more of a combined stress problem than anything).

 

[TLHS]

My understanding is that you're trying to avoid loading the weld root in tension. This is an issue in single sided fillet welds and in single sided PJP welds. At the root, you have an abrupt geometry change and possibly partial fusion, so you can get stress concentration and fracturing scenario. Take a look at the link below. It's the images and the few paragraphs above the linked location that are applicable.

(

http://books.google.ca/books?id=ANp...Q6AEwAw#v=onepage&q="root in tension"&f=false

)

If you have a PJP or fillet weld on both sides you should be fine, as your moment can form a couple. If you've got a CJP you should have fusion across the width of the joint, so I don't think it's an issue as there's no point to act as the stress concentration.

Technically, you could probably load the single sided welds in moment as well as long as the moment wasn't reversable and you were careful about what side you put the weld on.

 

[racookpe1978]

Repeat - precisely! - what the size of this proposed - extermely expensive!!!!! - "welded angle" is supposed to be.

You've used L250x250, and then a bit later said the leg thickness would be gretare than 1" thick ?? .

If this is a "structural element" and not some exotic DOD or NASA-specified space shuttle 10 million dollar a foot piece of titanium-impregnated gold-foil-wrapped gadget, then you cannot justify ANY sort of welding. The time and money you need cleaning and prepping the weld joint, welding the first side, back-grinding the other side, NDE, welding the second side, cleaning and NDE again both sides is lost. That money time and effort is wasted. There is no way ANY structural piece depends so absolutely on a few mm difference in leg length (comparing 250 mm to 10 inches) that prohibits going up a leg thickness by 1/16 to regain the lost few ounces of strength or torsion resistance.

Unless "he who specifies" also owns the welding company.

 

[hokie66]

racook,
You missed the point. The OP wanted a 250 x 250 angle, but where he is, that size is unavailable. Then SteelPE asked him if he was looking for an angle 10 x 10. I would have thought that was obvious, but apparently it is not to a lot of folks in the US. A 10 x 10 is not available either, so the issue is not a small one of geometry. Give the OP some credit...he just tried to talk in the dialect of the responders.

 

[TLHS]

Yeah, I've never seen a L254x254 in Canada at any leg thickness. The couple of catalogues I have from mills certainly don't include them. I'm assuming it's the same in the US.

It's reasonable to talk about L250x250 not being available in the US because there's no *equivalent size* available in North America. L250x250 actually is available in some other places because it appears to be included in the European standards. You can apparently also get L300x300 as well, which seems ridiculously huge, but probably has its uses.

 

[TLHS]

Yeah, I've never seen a L254x254 in Canada at any leg thickness. The couple of catalogues I have from mills certainly don't include them. I'm assuming it's the same in the US.

It's reasonable to talk about L250x250 not being available in the US because there's no *equivalent size* available in North America. L250x250 actually is available in some other places because it appears to be included in the European standards. You can apparently also get L300x300 as well, which seems ridiculously huge, but probably has its uses.

 

[ztengguy]

Bend a plate. done.

 

[Hokie93]

According to the December 2012 issue of Modern Steel Construction magazine (

http://www.modernsteel.com),

Nucor-Yamato and ArcelorMittal now produce L10x10 and L12x12 shapes. The article starts on page 58 of the magazine. The L10x10 is available in thicknesses ranging from 3/4" to 1 3/8". The section properties for L10x10 and L12x12 are included in the article. The shapes are included in the latest version of the ASTM A6 standard.

 

[Ron]

I thought the L10x10 was obvious as well; however, not easy to find.
One problem with using a plate member in those thicknesses is as dik mentioned...distortion. Further, there is likely a pre-heat and post-heat requirement for the welding that should be followed that perhaps the shop has not considered. Cracks are a likely problem.
If the application is in any way fracture critical, I would shy away from a welded plate. Also, extensive NDT would be needed to check the weld quality.