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Up Topic Welding Industry / General Welding Discussion / Determine the Area of a Triangle
- - By eekpod (****) Date 11-06-2009 14:29
Everyone,
I am trying to assist our estimating department in determining the deposition rate for weld joints. 

I need to determine the area of the joint configuration.

I can't remember how to determine the area of a triangle, can anyone please refresh my memory?

It's a 60 degree double bevel groove on a 4" thick plate, TC-U5-S(SAW).  Figure 1/8" root face an no root opening.

Once I know the formula, I can figure it out for other thickneses and angles (hopefully)

Thanks in advance  Chris

(I guess I shouldn't go on that show :Are you smarter than a 5th grader!!)
Parent - - By PipeIt (**) Date 11-06-2009 14:44
http://www.mathgoodies.com/lessons/vol1/area_triangle.htm

Base X Height X .5

or Base X Height divided be 2
Parent - By PipeIt (**) Date 11-06-2009 14:56
If I understood your cross sectional set up I come up with 4.5 square inches for the described joint.
Parent - By 522029 (***) Date 11-06-2009 14:45 Edited 11-06-2009 19:21
If you are not comfortable with "algebra and trigonometry",  multiply your triangle base and height dimensions (no degrees of angle) and divide by two. That will be the area of the cross section of the joint.  Multiply that number by the length of the welds for the amount of filler required.

Griff

What's with the times on the posts?  Its 8:48 am here and the post shows 14:45 (2:45 pm).

Answered my own question.  The time setting in my profile had somehow been changed to GMT instead of GMT -6.
Parent - - By Metarinka (****) Date 11-06-2009 15:32 Edited 11-06-2009 15:39
This might be of help to you, inside the strength calculator It is setup to automatically determine area for equal leg length joints. http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=105308;hl=estimator whoever made it must of been a genius :)

although I might add that calculations based on the area of a triangle are not 100% right because in truth usually a weld has a little bit of crown. At one point I had written a program that took that into effect,but I don't think I have it anymore it would end up  about 3-11% of the weld off the top of my head, of course this depends on how big of a crown you put. I took it into account because when you start getting into the thousands of pounds of wire for a project 5% is an extra 50 pound spool or so. 

When determining deposition rate, don't forget the efficiency of the process which varies. For example only about 50-80% of a stick electrode makes it into the puddle, and generally wire feed processes have some loss due to slag. not so sure about SAW though...
Parent - By PipeIt (**) Date 11-09-2009 13:19
Good point Metarinka I didn't consider the area of the crown, that would certainly be a factor.
Parent - - By Lawrence (*****) Date 11-06-2009 17:37
Chris

The "AWS Certified Welding Supervisors Manual for Quality and Productivity Improvement" 

Has great plotting for weld volume and efficiancy... Look at Chapter 10-Welding Econimics and Vairables

Great breakdowns for grooves and fillets both...
Parent - - By eekpod (****) Date 11-06-2009 19:31
Thanks guys for all the input, now I have a little project to work on over the weekend, besides raking leaves.
Parent - By G.S.Crisi (****) Date 11-06-2009 22:51
Take into account that the weld cross section isn't a perfect triangle because it has a reinforcement over it, i.e., the last pass welders apply as a "finishing" or "cover" of the weld.
Any welding consummables manufacturer (Lincoln, ESAB, etc. etc.) has tables that show the weight of weld per meter (or foot) of length according to the plate thickness. Those tables are usually free for the asking.
Giovanni S. Crisi
Sao Paulo - Brazil 
Parent - By CHGuilford (****) Date 11-07-2009 02:31
I use this formula:
(depth of the groove)squared X tangent of (1/2 the included angle)

This gives the triangular area of one side of the joint (both sides of the centerline), so multiply that by 2 for the double groove, assuming both sides are the same.  If nt the same calculate that separately and add results for each side.

When you have a root gap, be sure to add in (root gap x groove depth)

To help account for weld reinforcement, as Giovanni mentioned, I add 10% to the total groove area.

If you need the number of passes:
Calculate the PQR groove area and divide by the number of passes recorded to get the estimated cross sectional area of each weld pass.

Divide the weld groove area by the weld pass area to estimate the number of passes required.

I then estimate how many passes will be need to fill in the backgouge and add that to the total passes.
You won't be exact, too many variables in the welding, but it gets pretty close.

Now having said all that, I also have been known to sketch the weld joint and sketch in the weld passes that approximate fillet weld sizes I think the shop would run.  (As though the groove is simply a multipass fillet which it basically is).  It gets surprisingly close but it's hard to justify the method when someone wants to know what your "numbers" were.
Parent - By HgTX (***) Date 11-09-2009 18:28
People have given you the formula and a lot of other really good advice.  Here's something that explains why the formula works, so maybe you'll have an easier time remembering it:

http://www.mathgoodies.com/lessons/vol1/area_triangle.html
which refers to area of parallelogram, which is here:
http://www.mathgoodies.com/lessons/vol1/area_parallelogram.html

Hg
Up Topic Welding Industry / General Welding Discussion / Determine the Area of a Triangle

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