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Up Topic Welding Industry / Inspection & Qualification / smooth transition
- - By bert lee (**) Date 08-08-2011 14:45
when it says the butt welds must have smooth transition...what does it mean?
is it the weld must have a smooth transition to the base metal? is this term applicable to the weld to weld transition?

where to find the true meaning of smooth transition?

appreciate any input

thanks - bert
Parent - - By waccobird (****) Date 08-08-2011 14:53
bert lee

No Under-cut
No Lap
No excessive reinforcement.

My AWS A 3.0 that I have here does not give that definition.

Just my input
Good Luck
Marshall
Parent - - By bert lee (**) Date 08-08-2011 15:08
no undercut - ok
no overlap - not clear....overlap can have a smooth transition sometimes.
no excessive reinforcement - ok...no issue on the height but the weld bead to weld bead may not have smooth transition...especially when you are using gmaw process.
Parent - - By waccobird (****) Date 08-08-2011 15:21
bert lee
overlap is not thorough fusion with base matal and weld metal.
Marshall
Parent - - By bert lee (**) Date 08-08-2011 15:27
i understand but i'm not referring to fussion, see attached.
my concern is on whether you can apply this term to weld to weld bead.
Attachment: smoothtransition.doc (51k)
Parent - - By waccobird (****) Date 08-08-2011 15:46
bert lee

I sure would or you might be asking for slag inclusions or lack of fusion.

Marshall
Parent - - By bert lee (**) Date 08-08-2011 15:54
no marshal, i'm familiar with the weld discontinuities you mentioned
Parent - - By TimGary (****) Date 08-08-2011 20:03
I think they are talking about toe angles, but as they didn't specify a tolerance, it's left to interpretation.
In order to minimize the fatigue life shortening affect of stress risers at the toes of the weld, the smoother the transition, or the greater to toe angle, the greater the fatigue life of the weldment.

Tim
Parent - - By bert lee (**) Date 08-08-2011 22:13
i can understand "toe" transition between base metal to weld
what about the weld face? when you have multi-pass. do u need to have smooth transition
between weld bead?
Parent - - By ssbn727 (*****) Date 08-08-2011 22:33 Edited 08-08-2011 22:36
Bert,

Now why didn't you simply explain yourself previously in the manner you are now? One could have easily given you a good answer much earlier... 

It is usually required but then again, I'm not familiar with that specific EN standard and I worked from specific tolerances like Tim mentioned earlier...

No offense Bert but, getting specific and complete details from you are sometimes equivalent to pulling teeth from a live rattlesnake!:surprised::eek::roll::lol:

Respectfully,
Henry
Parent - By bert lee (**) Date 08-09-2011 03:35
no offence at all, you actually make me laugh i like your phrase “equivalent to pulling teeth from a live rattlesnake”:lol::grin:
i'll take your comment positively and will try to improve next time.

perhaps our european friends like 3.2, nantong, stephan may assist on this smooth transition written in EN ISO 5817

please refer to sketch, will you accept or reject the weld to weld transition based on the requirement of 1.9? let say no problem with reinforcement height.

thanks
bert
Attachment: smoothtransition2.doc (144k)
Attachment: DSC05268.JPG (110k)
Parent - By Blaster (***) Date 08-08-2011 23:54
I can't open your document, but does the standard you are using have an individual bead convexity limit?  Individual bead convexity limits are what I use as criteria for an "acceptable weld profile" when looking at bead to bead transition for the standard I commonly use. 

The standard I commonly use also requires a "smooth transition to the plane of the base metal", without providing a specific definition.  I use an angle of 135 degrees minimum.
Parent - - By G.S.Crisi (****) Date 08-08-2011 20:20
In my opinion, bert lee is speaking of a butt weld where the welding ends have a different thickness. Example: weld Sch 40 with Sch 80 pipes.
In this case, you can not weld them directly, you've got to prepare a "smooth transition" so the Sch 80 inside end matches exactly the Sch 40 inside end. This smooth transition must be, say, one inch long and is usually achieved by means of a conical stone.
Giovanni S. Crisi
Sao Paulo - Brazil
Parent - By bert lee (**) Date 08-08-2011 22:07
no not referring to uneven thickness..see attachment to my earlier post...its a EN std.
Parent - By ssbn727 (*****) Date 08-08-2011 22:20 Edited 08-08-2011 22:34
Well, there's certainly not enough information in the drawing to make an accurate assessment that shows where the one member of the joint is thicker than the other member...

What I notice is the fact that the lines for the columns in the drawing extend further up, which means that we're being shown an incomplete chart that doesn't show the headings for each column found in a complete chart.:eek::roll::lol::wink::cool:

Now if Bert could post the entire chart found in the EN (European Norm) standard where the previously posted incomplete drawing is attached to, we can then decipher the contents much better and therefore give a more accurate assessment of the purpose for the chart as it relates to the joint(s) in question.:lol::smile::wink::cool:

Respectfully,
Henry
Parent - - By TimGary (****) Date 08-09-2011 01:27
Prof Crisi, you're right when considering transition between different thickness material. I believe the appropriate transition there is 3:1.
The document that Bert Lee showed was for a butt weld with same thickness or flush fit material.

Bert, the "toe" of the weld is the point on either side of the weld where the weld face meets the base metal, or along the edges of the weld. If a weld is cold, or rolled over on the edges, or toes, the  resulting abrupt change in angle forms a stress riser, or an area in which stresses are increased during fatigue cycles. This elevated stress riser can cause a premature failure, or a crack that starts there and propagates into the base metal. Minimizing these toe angles prevents or reduces the stress riser which extends the fatigue life of the weldment.
Your document showed tolerance for height of weld reinforcement, but didn't include a toe angle limit, which is common for groove welds. Toe angle limit is often an inspection criteria for fillet welds. For example, the fillet weld toe angle limit where I work is 90 degrees, or the angle must be greater than 90 degrees for the weld to be acceptable.
Also, the groove weld reinforcement height I work with is 3mm, but the toes of the weld should have a "smooth transition" which means the weld reinforcement should not rise to as much as 3mm abruptly, but should rise gently in a smooth transition to promote fatigue life.

Does that sound right to you Professor?

Tim
Parent - - By bert lee (**) Date 08-09-2011 03:50
Tim appreciate your input, i believe you:smile:

well if you are in my position and your task is to say whether the weld visually met the requirement of EN ISO 5817 item 1.9, what is your judgement?
pretend that we are in the court room and the defence lawyer only wants to know your independent decision whether met or not met the 1.9 requirement for "smooth transition"

bert
Attachment: smoothtransition2.doc (144k)
Attachment: DSC05268.JPG (110k)
Parent - - By TimGary (****) Date 08-09-2011 11:06
Sorry Bert, not enough info for a definitive answer as there's no dimensions on the weld sketch, and but...
The EN criteria gives tolerances for three weld classifications, D, C, B, with B being the most stringent.
You didn't state the applicable class, but it's probably irrelavent.
If the sketch of the weld is drawn to scale, I would say that the weld has appropriate smooth transition at the toes, but not between the welds, but, because there is no set criteria for this, you could, maybe, get off on a technicality, after an argument, as it's open to opinion.
The height of the weld above the base metal, or dimension h, tolerance is very litte, only between 1.1mm to 1.25mm.
If the weld sketch is drawn close to scale, I would say the welds are too high to meet this.
The good news is that because the smooth transition at the toes is sufficient, the needed repair could be done by simply sanding the top of the weld down to below the acceptability limit, thus removing the lack of smooth transition between the beads.
Isn't weld inspection fun? :confused:

Tim
Parent - - By Shane Feder (****) Date 08-09-2011 12:48
Bert,
Transition is the changing from one level or height to another.
A smooth transition between base metal and weld metal is exactly what you have in your sketch.
If you had undercut, underflush, cold lap (sometimes called overlap) or excess reinforcement then you would not have a smooth transition.
However, stringer beads should overlap each other so they blend in smoothly and yours do not. Not sure if it is rejectable but I would recommend they grind the cap down to remove the notches between runs or run small stringers in the grooves to blend them in,
Regards,
Shane
Parent - - By bert lee (**) Date 08-09-2011 13:57
tim & shane thanks for your input.

sorry, i did not include the sketch dimensions as my interest is only on smooth transition between bead to bead welds.
there is no problem with the reinforcement height and the sketch is not drawn to scale.

the contractor said…..i will only rectify if you can prove to me that my welds are not acceptable based on the code’s acceptance criteria.

i'm imagining we in the court room, the defence lawyer might say to the third party inspector….you have rejected the welds purely based on your opinion...ok that is easy…he will then tell the judge i have no further question your honour....the basis of rejection is "opinion" while my client here is following his contract agreement based on agreed Code.  

shane, i can understand the required smooth transition between the base metal and weld metal "toe"...but i'm looking for a reference or links that will assist me to find out the true meaning and application of "smooth transition"..specifically if it refers to bead to bead welds.

bert
Parent - By TimGary (****) Date 08-09-2011 15:47
OK, so now we're getting down to the nitty-gritty.
I'm not familiar with the EN criteria you're working with. Have you checked all of the applicable code language for the definintion you're looking for? Look specifically for toe angles and weld to weld or weld to base metal fusion requirements, or stress risers.
If these are not clarified, the only way you could sucessfully argue a weld rejection in this case would be if the valleys inbetween the beads dip down below the surface of the base metal.
Also, what does the contract say? Often these types of discrepancies are detailed in contract documents.

":i'm imagining we in the court room, the defence lawyer might say to the third party inspector….you have rejected the welds purely based on your opinion...ok that is easy…he will then tell the judge i have no further question your honour....the basis of rejection is "opinion" while my client here is following his contract agreement based on agreed Code.  

"

That's exactly right. Without further code language to clarify the requirements, you can go no furter.
The reason why is beacause, as far as the weld integity is concerned, it's not a big deal.

Tim

Tim
Parent - By jwright650 (*****) Date 08-09-2011 14:15

>"Transition is the changing from one level or height to another."-quote


When I think of transistions this comes to mind:
I know this is from D1.1, but it conveys the message.
Attachment: D1.1transistions.pdf (47k)
Up Topic Welding Industry / Inspection & Qualification / smooth transition

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