ASTM 36 Beam fabrication

By catman Date 10-31-2002 02:15

We are a small mfg. and are contemplating producing our our own "I" beams for use in UL tank containment.
Has anyone had expierience in this application?
Beam sizes run from 18" - 24"
with lengths running up to 504"
I am the welding supervisor and have had alot of expierience in the structural field, but this is a little out of my league!!
I have read the Lincoln recomendations on fixturing and I have some background in the fixturing field.
We have the ability to run only 1 Pass at one time and do have a bug-go to run the process ( e71-T1/co2 sheild)
My biggest question would be:
1. What angle would the flange to web be set at to correct for the distortion of single pass per side at one time?

2. Do the laws of coefficient of thermal expansion apply here??

3. Is there an easy way ( or a program ) that could calculate weld amperage input to feet per weld that would give me a deflection ratio, given the thickness of material??

I used to work at a MFG'r that had a hot man for this in engineering but he is lost to me now...
I need some help and the dead line is drawing near and I need some answers to this problem.

As usual opur engineers came up with this idea and then told about it.
HELP!!!!

catman

By jwright650 (*****)

Date 10-31-2002 14:01

Catman,
Typically in our shop if we had to make plate girders we used the SAW process on a Bug-go and used a fillet weld at both sides of the web where the flanges are joined to web. On the side we started first we tilted the flanges out about an 1/8" or so and blocked it up in the middle if we did not what to add sweep to it. It was sort of trial and error like you are trying to get out of, but it didn't take but one ot two before you saw how much adjustment was needed. We ran passes on one side, turned it over and ran equal number of passes on the other side and never had "alot" of straightening to do. There was always some minor straightening and cambering to do. For that we used a blue tipped wrench and some hyd. rams to straighten the flanges.

Just curious, why you are making beams rather than buying them? W18's, W21's, and W24's are common beam sizes and are easy to find at any steel warehouse and full depth stiffeners or plating the flanges will really help if strength is an issue.

Maybe someone in the engineering field can post a calc. to help you in your problem of distortion from the heat input on one side. I'll keep a watch on this post because I'd like to know as well.

John Wright

By TimGary (****)

Date 10-31-2002 14:22

We use an "Automatic Beam Welder".
This consists of an adjustable 60' long x 6' wide jig fixture that has pneumatic clamps to hold the material while being welded by an automatic Sub Arc weld head. The welding is done on one side of the beam only. Welding the other side, for our application in AISC metal building frames, is not necessary.
If your Company is planning on doing a lot of this type of work, you may want to consider this option.
Tim

By pipewelder_1999 (****)

Date 10-31-2002 14:33

The AWS welding handbook Volume 1 has formulas for calculating deflection and distortion of welded joints. There are too many little squiggly symbols for my 9th grade tech math education. Its in chapter 7 and if you don't have access to the book I could write the formulas down but there is probably a great margin for error on my part.

G Austin
http://www.weldinginspectionsvcs.com

By jwright650 (*****)

Date 10-31-2002 15:47

I must have an old version of the AWS welding handbook Vol. I(seventh edition), mine only has 6 chapters. I found a formula that may help...

For T-joints with 2 continuous fillets:

Shrinkage = leg of fillet divided by the thickness of the plate
times 0.04(6.17)

Gerald, Is this what you are talking about?
John Wright

By jwright650 (*****)

Date 10-31-2002 16:50

Gerald,
I looked up the AWS Welding handbook on this Website and the latest edition of this is the nineth edition, so I guess mine is way out of date.

By CHGuilford (****)

Date 10-31-2002 15:06

Taken from the Lincoln Electric Procedure Handbook Of Arc Welding, page 3.1-8
.

By CHGuilford (****)

Date 10-31-2002 15:34

Check the Procedure Handbook of Arc Welding, by Lincoln Electric, page 3.1-8 for an angular distortion formula. I started to type it out but ran into some special characters. If you can't find a copy I could fax it to you. Not sure, but the Welding Handbook mentioned might be the same formula.

I would run a full thickness mock-up to determine flange tilt preset and actual angular distortion. 1/8" tilt is a good place to start as was already suggested. The same mock-up can be used to try out heat straightening procedures if needed.
You might look at thicker flange material for less angular distortion to see if that is justified over heat straightening costs.

The FCAW should be fine since fillet welds don't have to penetrate beyond the root of the joint (unless the customer says otherwise). We have used FCAW with good results although SAW is going to be faster if you have it available.

I also would cut everything long to serve as weld and equipment run-offs, cut to length afterwards.

Hope this helps,
CHGuilford