Heat Straightening help needed

By ctacker (****)

Date 08-05-2011 03:35

I need help, I think this is the first time in 30 years i have been stumped.

I have returned from vacation to a major screwup in our shop.

Here's what I got: an 87" tall Girder 50' long. (3/4" web- 1-1/2" X 15" top flange CJP double bevel full length to web. 1-1/4" X 13" bottom flange with 5/16" fillet both sides to web.)
I guess this thing either got built (or the welding ) caused a 7/16" reverse camber. EOR gave no more than 1/4" reverse camber for tolerance and 5/8" total on web flatness.

now the Idio..... er.. Craftsman decided he could pull the camber out by heating only the bottom flange ,creating waves( buckling- oilcanning) the web out of tolerance for flatness. he then decided to heat vees in the web ONLY about a foot down, thats where I say he F'ed up beyond repair. the web really started buckling then.

Now in all my experiance I have been able to pull small buckles out by heating star(asterick) patterns on the "dents". that don't seem to be working so well on this.

Has anyone ever run into a similar problem and solved it by heating? If so I would be interested in knowing how you did it.

Thanks in advance,
Carl

By DaveBoyer (*****)

Date 08-05-2011 04:07 Edited 08-05-2011 04:10

I really don't know dog doo about this, but My guess is He got too much area too hot on each try on the flange, and should have heated the flange and the "V" in the web at the same time.

Here are some links to look at:

http://isddc.dot.gov/OLPFiles/FHWA/009569.pdf

http://www.fhwa.dot.gov/bridge/heat.htm

By jwright650 (*****)

Date 08-05-2011 12:25

Dave has it...the flange hot shots and the V's into the web need to be done at the same time soaking the "K" area and everything...it takes two rose buds sometimes to work the heat in those areas simultaneously.

By ctacker (****)

Date 08-05-2011 12:48

I know how it should have been done, but unfortunately, it is too late for that. the problem now is trying to salvage the mess.

By jwright650 (*****)

Date 08-05-2011 12:50

Can you go in between the heated areas and heat some more(correctly)?...or do you already have enough camber in the piece now?

By ctacker (****)

Date 08-05-2011 15:53

we have enough camber now, I am with Brent about cutting losses, but the higher ups have not seen the light yet.
I can also be pretty damn sure they will listen next time about how to go about fitting/welding the next one.

By welderbrent (*****)

Date 08-05-2011 15:29

Without seeing it, sounds like a scrap and start over situation. At some point one has to cut their losses and just do it right the next time.

Just my two tin pennies worth.

Have a Great Day, Brent

By ozniek

Date 11-06-2011 10:50

Hi Carl

Any feedback on this one? Did you guys scrap it, or did you manage to save it? If so, how?

Regards
Niekie

By ctacker (****)

Date 11-06-2011 18:49

Niekie,
We were able to save it.
We Started by heating little spots, as small as the flame fom a rosebud would allow(2" spots). starting at the perimeter of the boil.
We heated about 8-10 spots around the outside of the oilcanned area and let it cool, then we started working closer to the center, but always staying just at the edge of the oilcanned area. .
always only heating 6-10 spots at a time with those 2" spots and letting them cool.
It took a little time but we were able to get it looking like it never happened.

I forgot about this post or I would have followed up.

Regards,
Carl

By ozniek

Date 11-07-2011 11:13

Hi Carl

Thanks for that feedback. This sounds like something I need to remember for the future, if I get into a similar pickle.

Regards
Niekie

By John Stewart (*)

Date 11-13-2011 19:28

Your source for future Flame Straightening Problems

http://johnstewartbooks.weebly.com/

By jwright650 (*****)

Date 11-14-2011 12:21

John....Great books...BTW
a "must have" in my opinion for anyone who is fabricating and welding