Little info on myself and my situation. I'm a QC inspector for a large structural shop. Currently some of the jobs running through our shop have some pretty large members with 4" baseplates. It's my understanding that preheat is required for any welding over 1 1/2" including tack welds(unless remelted by SAW, we're using FCAW). I'm catching alot of grief from production personnel for requiring preheat prior to tacking(understandably). I'm the first inspector thats required it be done. All of the inspectors in the past have let this slide, main reason I'm catching so much crap for it..."I've been doing this longer than you've been alive and never had to do that!!!"(I'm 24, another problem I have to deal with) How do you guys handle this? do you require it? let it slide? I'm struggling quite a bit even justifying it to myself just because of the safety hazards it creates. Hanging a 4" baseplate thats 225 degrees isn't fun. But at the same time neither is underbead cracking....... Appreciate any help you guys can give.
Thanks
Jrabbass
First Welcome to the American Welding Society Online Forum.
Your QC Manager would be the one to talk to.
A large structural shop should have procedures giving direction for how it does things so as to consistently deliver a Quality Product no matter the knowledge of the personnel attempting the task.
AWS D1.1 says All welders, welding operators, and tack welders shall be informed in the proper use of the WPS and the applicable WPS be followed during the performance of the welding.
Again Welcome to the American Welding Society Online Forum.
Good Luck
Marshall
Definate preheat. Im thinking it MAY be acceptable to not preheat the tacks, treat them as a defective weld and remove them out completly before welding that joint. As long as they are not cracked, this might be acceptable. But yes, D1.1 says to preheat.
Jrabbass,
WELCOME TO THE AWS WELDING FORUM!!
Marshall and Allan have made some good points.
If your employer is a 'Large Structural Shop' then they should have established WPS's establishing how ALL shop welding is to be performed. Those procedures should have been accepted/approved by the Customer and/or their engineer. As the approved Welding Procedure for the job at hand it is to be followed for ALL welding done on their job.
The proper chain of command would be to go to your QC Manager/Supervisor and raise the issue. It will be their call on where it goes from there. I would though, be very careful to include any lack of proper procedure on your daily reports. It may be their call, but it is still your responsibility to assure proper QC.
Age and how long a welder has done something has nothing to do with the facts at hand. Codes and procedures have changed through the years as more research and experience has contributed to more available knowledge to allow more probability to accomplish quality with little risk of failure. Besides, most welders with that attitude have been doing their job WRONG for all those years. So how long they have done so is not a reasonable argument or basis for continuing to do the job wrong.
At 4" thickness, I'm going to guess your base plates are probable in excess of 300 lbs. In other words, they are going to be using a crane to hang them anyway. They should be set in place and can be held with welders aids with no tacks, then, PRE-HEATED and tacked. THEN, welded.
Proper procedure with quality results.
Have a Great Day, Brent
The problem with not pre-heating is that the tacks often crack, thus causing mis-fit issues and extra effort in completely removing the tacks prior to welding. A lot of welders won't remove the cracked tacks and just weld over them which can definitely reduce the fatigue life.
Having been in your situation years ago, I was able to work out a compromise in that the fitter would not have to pre heat the entire part prior to tacking, but rather use a cutting torch to heat the exact spot to be tacked for about 30 seconds immediately prior to placing each tack. This proved to be enough to prevent cracks.
Regardless of everything I just said, it's your job to ensure the work is done according to an approved procedure.
If the procedure is inadequate, initiate a revision.
Tim
Topic American Welding Society Services / Technical Standards & Publications / Preheating prior to tack welding
