Partial pen double bevel groove weld

[dozer]

OK, break out "Structural Welding Code - Steel" AWS D1.1:200 for this question. Now go to p. 54, the figure at the bottom for double-bevel-groove weld. Look at the line for SMAW welding process. Everybody with me? I don't specify partial pens very often (maybe never) so I'm probably about to show my ignorance.

According to the chart T1 can be 5/16". The root face (f) has to be at least 1/8". This leaves 3/16" for S1 + S2. The total weld size (E1 + E2) = S1 + S2 - 1/4" which gives us negative 1/16" !!!

What am I not understanding here?

 

[GRoberts]

I agree with your iterpretation, which would mean that someoene should be doing a little more table checking bore the next edition is published. I don't think it is just a typo though, because the metric figure comes up with a -1mm However, if you are specifying a partial pen groove weld, you aren't worried about fatigue or loading of the root, why not just specify a fillet weld instead?

 

[JAE]

Does look strange but try this "explanation":

The negative is for the effective weld size (E) which implies that for a 5/16" plate, or a 6/16" plate (3/8) you would have a negative or zero weld capacity - in other words, you can weld it but don't count on any strength.

For plates larger than 3/8" you begin to have a positive (E) value and therefore can count on the weld for strength.

There are cases where a weld can be specified but not required for any structural strength per se (such as a compressive bearing stiffener against a flange).

Just a try - but I agree - it looks fishy.

 

[rmp319]

The Tolerances AS DETAILED allowance is Unlimited and the As Fit-up allowance for (f) is +/- 1/16". Based on this, a detailed joint as you described could have a 0.0" (f) root face and the fit up allowance of +/- 1/16 (f). Section 3.12.3 allow for the use of the stated Tolerances on design or detail drawings.

Any Help???

 

[CWIC]

I think the negative value would change and the As Fit-Up tolerance of +/- 1/16" would apply.

 

[CWIC]

Robert<
Good to see were on the &quot;same page&quot; for a change.
CWIC (DGXL)

 

[dozer]

Thanks for the responses. I'm just glad to know I'm not going totally stupid. Just to let you know the detail was suggested by someone else. I nixed it and went with fillets.

Something that rpoche brought up that I don't understand is why have an unlimited tolerance? Makes the whole issue of specifying a minimum moot doesn't it?

Anyway, I'm not closing this discussion. I'd still be interested to hear people's theories but for my particular case I'm going with the theory that when welding a 5/16&quot; plate like this you basically can't count on the weld for strength.