Defination about remelt tack weld and incorporated tack weld

Date 02-02-2013 02:59 Edited 02-02-2013 03:01

This are two sentense shown in my project requirments that:" Tack welds which are incorporated into final welds, i.e., not remelt verified, shall be made with an approved WPS and accepted by the Engineer."

"All tack welds installed under the “remelt provision” shall be qualified by demonstration, macroetch testing as directed by the Engineer. The WPS joint detail shall detail the tack weld and all supporting WPS process information."

My question is as follows
1)What is the difference between tack weld being remelted into the final weld and tack weld incorporated into the final weld?

2)Is remelted tack weld being remelt totally? Is incorporated tack weld just melt a part of it, to shown well fusion between the tack weld and final weld?

3) What does “Tack welds which are incorporated into final welds, i.e., not remelt verified...” means?

By 803056

Date 02-03-2013 16:59 Edited 02-03-2013 17:01

I am not saying this is correct, but my interpretation is:
a) Incorporated tack weld: the tack weld is incorporated into the completed weld if the tack weld is not removed before depositing the production weld. Additional weld is “added” to the existing tack weld to extend the weld to the required length and size. The added weld is fused to the existing tack weld.
b) Remelted tack weld: a tack weld that is remelted is incorporated into the final weld when the tack weld is completely consumed by the completed weld. No evidence of the tack weld remains. The tack weld is completely melted and diluted or dissolved into with the production weld.

The photomacrograph of a tack weld that is incorporated into the final weld would be visiable in the cross section. A remelted tack weld could not be seen in the photomacrograph.

Best regards - Al

By welderbrent (*****)

Date 02-03-2013 22:59

Interesting.

I concur with Al's interpretation of your questions.

When he says "completely consumed", you need to be pretty hot to accomplish this. That is normally considered a function of using SAW and welding over tack welds placed via other processes.

I am a little curious though Al, would it not be possible to weld over tack welds to 'incorporate' them into welds as well as using the tack weld as either the starting or ending point of a longer weld. At least, that is how I interpreted what you said.

Have a Great Day, Brent

By 803056

Date 02-03-2013 23:26

Yup, do it all the time wth a cascade welding technique.

The main difference is whether the tack shows up in the macroetch or not.

Al

By yyq4794 (**)

Date 02-04-2013 01:04

Thanks a lot, Al.

So tack welds can be shown in the macroetching if it is incorporated by the following pass. I hope I have catch your point. Right?