Who qualified to do Tack Welding?

[WE17]

Hi_experts
Can anyone explain who can do tack welding in production? I am working in pressure vessel Fabrication. I have an argue with client and show ASME VIII UW.31 C, My interpretation are for permanen welder must be do with welder qualified with asme IX but for non permanen weld can do by anyone(like fitter) but using same procedure (WPS). am I correct ? Please help

 

[metengr]

UW-31 states
Tack welds, whether removed or left in place, shall be made
using a fillet weld or butt weld procedure qualified in
accordance with Section IX. Tack welds to be left in place
shall be made by welders qualified in accordance with
Section IX, and shall be examined visually for defects, and
if found to be defective shall be removed.

The procedure and welder must be qualified.

 

[DekDee]

metengr,
"Tack welds to be left in place shall be made by welders qualified in accordance with
Section IX"

What if the tack welds are not left in place - eg temporary attachments, tacks removed prior to welding etc ?

I agree the tack welds must be in accordance with a qualified WPS - regardless of whether they are removed or not.
However, based on UW 31 (c)temporary (or as WE17 calls them - non-permanent) tacks do not require a qualified welder (IMHO),
Regards,
DD

 

[XL83NL]

DekDee; I have the same question. Wonder how VIII Div 1 deals with this. B31.3 is clear in this; both temp. and non-temp. tackwelds shall be made by qualified welders.
Regardsless of Code requirements, I think it shouldn't matter if it's a temp or non-temp. tack; it should be your company's standard practice (by means of e.g your quality system) to only have qualified at work on Code stuff.

 

[metengr]

First, this is not production welding. I can see how this section can create confusion. After further review, this section of the code (UW-31)deals only with cutting, alignment and fitting, which is not really production welding where you need a qualified welder and procedure (based on pervious sections). For tack welds limited to alignment and fitting purposes and they are considered temporary, they can be applied by the certificate holder or a non-certificate holder (if you read further into UW-31) simply using a qualified welding procedure. At the end of the day, your Quality Manual must describe this activity and it must be approved by your AIA. In most cases, Certificate holders use qualified welders and as such, it becomes a moot point.

 

[XL83NL]

thanks for your POV metengr. still find it strange as to why ASME allows welding by a non-qualified welder on a temporary tack weld for VIII-1 work, whereas it does not approve this for B31.3.

 

[weldstan]

B31.3 is primarily an Owner's Code. It reflects the collective experience and needs of Owner/Operators.

 

[WE17]

Dear Gent's
Thankyou very much for the response it is very helpfull

 

[steakman911]

Tack welding: If the said tack welds are to be left in place then those tacks must be performed by a Qualified Pressure welder. That makes sense as the tacks become part of the pressure weld...right.?

In my part of the world, tacks right in the root are pretty much "verboten" and we use "bridge Tacks" instead. These tacks are done such they bridge across the gap without affecting the root.

Eg: a 6" Sch 80 pipe - 3/32" root opening. Using a gap rod of 3/32" a fitter who can weld or a just a regular journeyman then takes a 3/16 or 1/4" electrode (7018 with the flux knocked off), bends a 1-2" pce of that 3/16" rod in a vice and places it in the groove but not into the root. He then tacks either side using 7018 for about 1/2" to "tack" that section of the pipe. He then bends/breaks the remaining pce of tack rod off and goes to the next tack. Very very common up here in Alberta. This also serves to reduce the amount of root pass tie-ins a welder has to do on a weld as well.

hmm, should do a short video on that and put it up on U-tube..lol

 

[GenB]

Amazing. Pls post the video link. Ya will be honored

 

[steakman911]

..the other advantage of bridge tacking is that one does not require a Certified B Pressure welder to make said tacks. In Alberta we have Journeyman welders, and then B Pressure Welders . Typically a B welder will earn from $7.50-10/hr more than a journeyman and as such is employed to make pressure welds..not tack. Pretty much most of the shops that I've been involved with will use pipe fitters performing "bench fitting", & doing their own tacking...all using the bridge method. Occasionally a journyman will assist a fitter.

I took a look on u-tube..nothing there. When I get a chance, I'll post one up and link it here.

rgds,

stk

 

[verdiblue]

hi fellas

interesting comments. im in australia and we only use welders for bridge tacking or pipefitters who have been tested - usually with a 2,3,4f plate. this is always a client spec and is normal practice.