Interpretation VIII-1-89-264

[FoxRox]

From Interpretation VIII-1-89-264:

Question (5): UW-33(b) indicates that offsets within the limits of Table UW-33 must be tapered, whereas UW-9(c) notes that only sections which differ in thickness by greater than 1/4t or 1/8 in. need the 3:1 taper. What is the distinction?

Reply (5): UW-33 refers to alignment tolerances only. UW-9(c) and UW-33 are design requirements which specify taper transition requirements when welding sections of different thicknesses. Both requirements must be met.

The reply here seems contradictory to me. It first says UW-33 is an alignment tolerance only. It then says UW-33 is also a design requirement. UW-33 is in the fabrication portion of UW, not the design portion, so the second sentence in the reply seems contradictory with the code.

Is it possible the second sentence was meant to reference UW-13? UW-9(c)(1) and UW-13(b)(3) both use the same language to define the rules about transitioning between thicknesses. Both allow 3 to 1 welds without restriction. Neither mentions UW-33. Even if there is not a mistake or typo, to ask a more general question, is it typical/normal to call a fabrication requirement a design requirement?

If I was to submit a question, it would be this: Are 3-to-1 tapered transitions per UW-9(c)(1) or UW-13(b)(3) ever allowed to be done with built-up weld material outside the confines of table UW-33?

The answer seems to be no, but I'm just curious if anyone has any experience or insights into this poorly worded (IMO) interpretation.

To ask a more general question, are fabrication alignment tolerances independent from the design of the joint, or are they one in the same? Is it apples and oranges or just a bunch of mashed up bananas?

 

[bpv66]

I believe there is a typo in "Reply 5" and the second reference to UW-33 should be UW-13(b)(3). If you are outside the UW-33 tolerance you will need to re-fit the joint. The 3:1 taper is only permitted if you are within the UW-33 tolerance. That's they way I interpret UW-33 anyway.

 

[FoxRox]

I hadn't put all the numbers together before, but there is functionally no way UW-33 can be intended to restrict tapered transitions between different thicknesses per UW-9 and UW-13. They would entirely contradict each other.

Example 1: 5/16 shell welded to 3/8 head. This is not even considered a tapered transition under UW-13 because .375-.3125=.0625 is less than .25*.3125=.078125. If this is considered "misaligned" under UW-33, then a taper is allowed per UW-33(a) and is required to be faired or welded per UW-33(b).

Example 2: 3/8" shell welded to 1/2" head. This is considered a tapered transition per UW-13. A 3-to-1 taper may be achieved by removing material or adding weld material. If this is considered "misaligned" under UW-33, then it looks like this is a completely illegal joint because .5-.375=.125 is greater than .25*.375=.09375. UW-33(a) does not allow the tapered transition.

The contradiction in example 2 is universal. The definition of a tapered transition in UW-9 and UW-13 is always outside the limits of Table UW-33. This makes no sense if UW-33 is a design requirement as per the interpretation I referenced in my first post.

I would appreciate any insights or experiences members can offer about this. I have a very experienced AI telling me that example 2 is allowed, but only if you machine or grind the ID of the 1/2" head to align with the 3/8" shell within the bounds of Table UW-33 (so less than .09375 offset) before welding. I cannot reconcile this with the language of the code or any official interpretation about UW-33. I'm confused!

 

[FoxRox]

Bump.

If I'm missing something painfully obvious, I still haven't found it. Still hoping from some clarity on this.

If I have not been clear in describing the problem, please ask and I will try to re-word it.