American Welding Society Forum
I'm in disagreement with our QC/QA department about concavity in the root. Our shop builds pressure vessels, utilizing ASME Code Section XIII, Div.I. which states: That concavity due to the welding process on the root side of a welding circumferential butt weld is permitted when the resulting thickness of the weld is at least equal to the thickness of the thinness of the member of the two sections being joined and the contour of the concavity is smooth.
Our quality departments position is, that the difference in the concavity of the weld and the inside wall of the pipe or vessel, can be compensated for in the reinforcement to obtain the weld size needed to equal the thinner member.
In my past welding experience, I have never know weld reinforcement to be include in the groove weld size, and the way I read the code, that is still the way I interpret it.
So, if anyone can shine more light on this topic and maybe even provide some code language or any other documentation help me better understand this, I truly would greatly appreciate it.
ASME: Always, Sometimes, Maybe, or Except
Depending on the specific construction code and fluid service, they will permit some root concavity provided the weld size (including reinforcement) is at least equal to the thickness of the thinner member. The acceptance is conditional provided the face reinforcement is within acceptable limits.
If the permitted face reinforcement is 1/16 inch, then the allowable root concavity is 1/16 as well. Again, words of warning, the allowable is conditional on the construction code and the fluid service. It does not apply for all conditions, all construction codes, all fluid service.
The face reinforcement is not typically included in the design and determination of the weld strength from a design standpoint.
Hey, I appreciate the response, I've been looking over ASME Code, Section VIII, Div 1 which is the code that primarily applies to what we do at our shop. Part UW-35 FINISHED LONGITUDINAL AND CIRCUMFERENTIAL JOINTS has a maximum reinforcement table, that specifies reinforcement requirements for ranges in material thickness.
I have some questions regarding, note #9, of the above mentioned table that states: Concavity due to the welding process on the root side of a single welded circumferential butt weld is permitted when the resulting thickness of the weld is at least equal to the thickness of the thinner member of the two sections being joined and the contour of the concavity is smooth.
#1- the passage " the resulting thickness of the weld is at least equal to the thickness of the thinner member" .
Does the accompanying table imply that you add the reinforcement to acquire the weld size?
Does the reference to "thinner member" suggest members of different thickness and counter boring is required?
Is this one of the codes that permit concavity?
I'm really not trying to overthink this scenario, but it is extremely important that I get the correct interpretation and understanding of the code
I agree with Al in that there can be more than one interpretation of of UW-35. In my world, a concavity is normally detected following radiography when a darkening is noted in the root area. This can be a suck-back as a result of a stop, or just a gradual darkening. Once a lack of penetration or lack of fusion is ruled out the density of the concave area is compared to the density of the base material. A concavity darker than the base material indicates that the thickness at the weld is thinner than the base material. An equal density or a lighter density of the concavity indicates the thickness at the weld is equal to or greater than the thickness of the base material.
At this point the QC department can get an actual measurement (if accessible), and could perform a repair. If not accessible, QC can accept a positive RT interpretation using the density method, or take exception to it and opt for repair. Getting the AI involved is also a good idea as he/she will likely review the film anyway. I prefer to not to use the AI as a the decision maker, but rather explain to them that QC has made a particular decision based on certain information... then let them agree, comment, or dis-agree. I've seen shops add another layer to the cover pass because more reinforcement will lighten the concavity, but generally this would apply to the entire weld, not a localized area. This will work, but one must be mindful of the height of reinforcement.
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