PREHAET of WELDED STRUCTURES

[ghan]

A plate was welded to a column by E6010(ASME standard of electrode) as root pass and E6013 (ASME standard of electrode)as filling passes. All materials are st37 and the thickness of base plate is 25 mm and it should be preheated about 70 C in conformance with ASME, but it wasn't preheated.
How can I test the column to determine whether we can use it in the structure or not?
I should add that the results of all N.D.T.s including U.T.,M.T.,V.T. are accepted but I can't reffer to them to judge about the soundness of the weld in this case, can I?
And what is the solution to overcome such a problem after welding?
I would appreciate any suggestion,
GHAN.

 

[flamby]

Of course you can refer to NDTs to detect any flaw in welding.
However, we normally dont require preheat of plates of 25 mm thickness. If the temperature of the plate was more than 20 degree C at the time of weld, that should be acceptable if the NDTs do not prove otherwise.

 

[evelrod]

Odd combination of electrodes. Haven't seen anything like that in about 40 years. 'flame' is right on about pre heat but I sure would like to know what you have there.

Rod

 

[deanc]

What does your WPS,Welding Procedure require? Do you have one for no preheat with these parameters? If not,run one and qualify it. Then present the NDT results.

 

[ghan]

evelrod I totally agree with you ,the vendor offered to change E7018 with E6013 with preheating in return, however all WPSs reguire all thickness in excess of 20 mm be preheated. As you know one of the purposes of preheating is to reduce Stress after welding so I can't detect the residual stress with NDTs.It just can be guessed by deformation occure after welding, and it is to some extent occured in the baseplate.I need a practical solution to test the column that the deformation is tolerated or not?

 

[deanc]

"ghan" That is the reason you qualify a WPS,to see if the procedure{without preheat} is acceptable. It is also a good reason to use the same parameters as the item in question. This will require mechanical testing.

In other words"CYA" after the deed is done.

 

[ghan]

What do you mean by "CYA"?

 

[Rjeffery]

deanc means "cover your a.." I mean "buttocks" by proving the procedure works in the real world, first.

 

[evelrod]

ghan, I would definately go with the E-7018. E-6013(AC-DC) is the very first fluxed electrode and is mostly used in home/buzz box applications these days. Last saw it on a jobsite on the Sandia Peak Tramway in 1965. Weld procedure with low hydrogen fluxed electrodes is easier and more reliable/repeatable. The root pass with E-6010 is still used in piping but, I haven't seen this in structural in a long time. Since maybe 1976 in an AWS test. Perhaps substitute E-70xx (7010?). You will still need mechanical testing.
"CYA" that's what "as builts" are for? LOL

Rod

 

[Jeffro]

Ghan all WPS's have essential variables including that for preheat, therfore if the welding was done outside of those parameters it must be considered to be unacceptable. This leaves you with 2 choices, cut out & remove the offending weldment or requalify as suggested earlier by Deanc.
I also agree with evelrod on the choice of electrodes if NDT is required it would suggest reasonable stresses are going to be place on the member and therefore higher quality electrodes (low hydrogen) should be utilised. hope this is helpful.

 

[Metalguy]

ghan,

Preheating to low temps. doesn't do much to reduce the residual welding stresses. It is primarily to reduce/prevent the formation of martensite or bainite during cooling of the HAZ.

I don't have the chem. of your steel handy, but if you post it it would help.