Hello Guys,
Noticed a posting from Dec 2002 where this was discussed and was hoping to see if I could obtain some more information to assist in my "battle" with our contractor.
The machine is being built in Australia to American design and the contractor has nominated AWS D1.1 Pre-qualified joints for the welding.
In hindsight (and with a bit of "off the record" help from John Gayler) I now realise that the respective joint designations should have been identified on the drawings and we would not be in the position we now find ourselves.
We have a single bevel T joint on a 50 mm(2") plate and the weld symbol shows 50 mm (depth of preparation) to the left of the groove symbol with a 12 mm (.50") fillet on the opposite side.It does not have the weld size/depth in brackets.Following UT a majority of these welds were found to have root defects (lack of pen/fusion) to which the contractor replied that they were partial penetration welds as they were not nominated for backgouging.
My question is if your depth of preparation is the same as your plate thickness then that means your root face is zero. How can you possibly not have a CJP weld (FCAW). Figure 3.3 BTC-P4-GF states under tolerances that you must have a minimum root face of 3 mm (1/8") and even under "As Fit-up" it allows no more than +/- 2mm which I take to mean that you can have a maximum depth of preparation of up to 49 mm and still be classified as Partial Penetration.
The next joint in question is a single vee groove with bulkheads acting as backing bars.Again the depth of preparation is the same as the plate thickness.For some reason the backing bar symbol has been omitted from the welding symbol. The difference with this joint is that it has 6 mm (1/4") and 45° shown inside the vee on the symbol which as you are all aware are the root opening and groove angle measurements.
Again we have found defects and surprise, surprise again we are informed that they are partial penetration welds.
Section 5.22.2 states that 4.7 mm (3/16") is the maximum root gap allowed for PJP welds. ( It is 1" and 2" plate only)
The measurements shown are exactly the same as those shown in Figure 3.4 FCAW B-U2a-GF which happens to be in the CJP section.
As the joints on the drawings appear to be CJP, it concerns me deeply that after testing they are suddenly all becoming PJP.We appear to be getting PJP welds by default.
Your thoughts would be greatly appreciated,
Regards,
Shane
On your first joint,
It is my understanding that a welding symbol that shows a depth of preparation that is not supplememented with a depth of penetration is understood to have/require a weld size equal to the depth of preparation. Without the bepth of preparation I don't have a welding symbols standard available and may be completely off base. But thats how I remember it.
On the second joint
If no weld size is specified. The weld is CJP. Period. The groove and root opening are sufficient to acheive CJP but a little more of either would be ok.
There my opinion.
Have a good day
Gerald Austin
I agree with Geralds interpretaion of the weld symbols.
However, as the work has already been done, I would consult the design engineer before rejecting the whole project.
If the calculations show that these weld joints are required to be full pen in order to maintain structural integrity, then you have no choice but to reject.
If a partial pen is acceptable by engineering, then you may want to consider whether it is worth the time and money involved to take the issue further.
Tim
Shane,
I don't have a lot of time at this moment, but I do have a few thoughts for now.
FCAW weld sizes are 1/8" less than the depth of groove preparation as can be seen by the "s-1/8" note in Figure 3.3. So unless the weld is designated as CJP or noted that backgouging is required, I would interpret the weld as PJP. Well, that's not entirely true, normally I like to verify the intent on PJP weld symbols because they are often misused.
Now in your other case, I would interpret the weld as CJP because the backing is provided and the B-U2a joint dimensions would leave little doubt as to what is desired, in my mind. As Gerald said, if no depth of preparation or weld size is provided, the weld is CJP by default.
Where the contractor opted to use D1.1, I would say the welding symbols should be in compliance with AWS A2.4 standards. But what do your contract drawings indicate? Those should be the deciding documents, unless they have been excluded in the bid.
Tim's comment is accurate, if the weld is adequate for the intent, the repairs may be too costly. It sounds like you would end up sharing rewirk costs with the contractor. Engineering review is advisable.
Chet Guilford
My understanding is that generally a complete penetration weld must be either welded on to backing, or backgouged and welded on the second side. This would suggest that the first joint is partial penetration, while the second would be complete penetration.
However, the partial penetration weld combined with the 1/2" fillet should provide more capacity than the strength of the 2" plate. I would only be concerned if the joint was subject to fatigue loading, in which case there should have been a note on the drawing or project specifications stating that all joints must be complete penetration.
Harold
Shane
At the risk of being redundant, here's my opinion.
The omission of depth of bevel and groove weld size dimensions from the welding symbol requires complete penetration only for single groove welds and double groove welds having symmetrical joint geometry.
Actually that as quoted in AWS A2.4 para. 4.2.2.
Wish I would have said it first.
Lew
Thanks for your response guys,
The strange thing is we have just had a meeting with one of the design engineers and they have admitted that the first joint should have had backgouging and was a drawing mistake but that the second joint was partial penetration.I am completely mystified at their reasoning because they also have another joint not previously mentioned that has a backing bar symbol on the detail and they are claiming it is a PJP.
The reason the arguement is getting so messy is the fact that the contractor is the OEM and we are the Owners Representative and we are both claiming to be the "Engineer" as per AWS D1.1.
I know this may sound ridiculous but why can't we have an international welding code/standard (for each discipline-structural, piping, tanks etc) that is recognised world-wide.
Here in Australia I am regularly exposed to American, Australian,British, European,and now Japanese welding codes and it can be a pain in the butt as every countries code seems to have different acceptance criteria and different interpretations. You inspectors in the US who only have AWS, ASME and API to worry about don't realise how lucky you are.Personally I find the American codes the easiest to work with but that is only due to my familiarity with them.
Sorry, I got off the track a bit there,
Best regards,
Shane
I wish it were that simple, LOL. Here in the United States, I have also worked under the guidelines of: TUV, PED, and UOP codes. In my opinion, PED and TUV are the most stringent. If a design engineer calls out a .25" fillet weld, it has to be a .25 fillet weld. No bigger, no smaller. They will bring in their own inspector to witness weldor qualification, and requalification. Every weldor holding a PED or TUV qualification, must be requalified every 2 years, in every postition.
Mike
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