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> bead width using mag
B186
post Aug 6 2017, 07:34 PM
Joined: 4-Jan 06



hi all, getting a few mixed opinions at work regarding the max bead width when capping off heavy plate butts, 15mm thick and upwards. Done in pa position,1.2 wire and heavy gas. Any thoughts?
try_some_welding
post Aug 8 2017, 08:14 AM
Joined: 14-Jan 07



I'm looking with interest too, following this question...
Uncle D
post Aug 8 2017, 01:23 PM
Joined: 9-May 04



If there's no Welding Procedure to follow I'd personally always use stringer beads
msmkua
post Aug 8 2017, 01:46 PM
Joined: 23-Jan 09



Hi,
previously done the experiment to compare the Weld metal Charpy value using stinger beads and wide bead technique on FCAW process vertical up . The width of the single run weld bead on capping run was 40mm.
Chrapy test at -40 showed almost similar results in compare to stinger beads deposit.
Regards
MSMK
Uncle D
post Aug 8 2017, 04:29 PM
Joined: 9-May 04



A weave of over 1.5 inches??!! 8-/
Technic Al
post Aug 11 2017, 07:30 PM
Joined: 14-Oct 03



Its down to the Heat Input. If theres a spec a full width weave is likely to be excessive. The effect on CVNs maybe masked a little by how much of the cap actually ends uo iin the test piece.
B186
post Aug 14 2017, 07:32 PM
Joined: 4-Jan 06



that's my take on it Al, it would be wrong to state a definitive size without taking into account the welding parameters... the question arose because some younger generation lads at work were adamant it was 8, maybe 10 mil bead width because that's what they were taught at college
PulseGenerator
post Aug 22 2017, 05:36 PM
Joined: 14-Nov 14



As a welder, we were taught as a rule of thumb to limit it to around 10X wire diameter for FCAW or bare wire MAG. PQR's were then done with this rule of thumb and performed satisfactorily in hardness and CVN tests in general.

As a QC inspector, I used to advise welders on our experiences and most seemed to follow suit. However, so long as his HI is within the range of the WPS, then there's no real issue providing the WPS doesn't state maximum bead widths.

As a RWC I generally still like to work around the 10X wire diameter rule, for no other reason than that's what we were taught back in the day.

Bare in mind, if the welder is capping off the butt with a Wallsend Weave, then it's highly likely that he's doing it in the body of the weld as well.

This post has been edited by PulseGenerator: Aug 22 2017, 05:38 PM
Technic Al
post Aug 22 2017, 11:10 PM
Joined: 14-Oct 03



The 10x has no scientific basis......Heat Input is important and differs with the material. A cover all 10x is not a good rule
excess pen
post Aug 23 2017, 10:56 AM
Joined: 29-Mar 10



As a Inspector, all welders should have a wps to follow and it should state there the maximum bead width. If there is an debate check the WPQR and that will state heat inputs, bead width etc. Usually the rule is about 8mm bead width (Stringer Runs).
Arctic
post Aug 23 2017, 12:42 PM
Joined: 27-Sep 12



.... full weave caps.

If it's only the cap there should be negligible effect on Charpy and/or Tensiles (as they specimens are taken sub cap), but may affect Hardness.

However, if the cap meets visual and NDE standard, can't see an issue with it - IF it's overall faster than a multi run stringer cap.

One other issue here, if the NDE is X-ray, a full weave cap makes RT interpretation of bead/body of the weld a whole lot easier.
Technic Al
post Aug 23 2017, 06:46 PM
Joined: 14-Oct 03



Full weave cap is likely to be high heat input which WILL affect CVNs.....on mild steel it will probably improve them but could have an adverse effect on the Tensile......a bit like Stress Relieving....maybe 50 points.

Also the CVN specimen may or may not contain some of the cap. Depends on thickness and who is doing the machining.
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