D1.1 Figure 3.2 & 3.3 - Prequalified Joints

By troberts Date 03-09-2019 23:10

This topic has been discussed before. But, just when I thought I fully understand the figures, a questions arrives in which I cannot find the correct answer.

Here is the questions:

For the prequalified joint B-L2c-S, what is the range of root face dimensions, as fit-up, permitted for a base metal thickness of 1 inch?

(Go to page 70 for the D1.1 2015)

Possible answers:

a) 3/16 to 5/16 inch
b) 1/4 to 5/16 inch
c) 1/4 inch maximum
d) Not limited
e) 0 to 5/16 inch

My solution is [e]. My reasoning - Because the questions does not give us the detailed root face, we are to assume the full ranges. Therefore the detailer can detail "f" as 0- 1/4" max. Therefore, the as fit-up is 0 to 5/16 inch. 0 because "f" can't go below zero, and 5/16" because + 1/16 with 1/4" = 5/16".

That being said, the answer is [c]! 1/4 inch maximum.

I can't make sense of this. That's not even a range! The question asks for a range! Is this question wrong or am I missing an important concept with these figures?

Any help would be appreciated.

By SWN1158 (***)

Date 03-11-2019 14:18

Page 70 in the 2015 D1.1 is for PJP joints.

Are you testing to become a CWI?

The prequalified root face that's permitted for a base metal thickness of 1/2" to 1"..... F = 1/4" max, which indicates 0 - 1/4" max.

The "As Fit-Up" is + 1/16 - 0..... which is 0 - 5/16"

In your list of five possible answers, the answer is E.

And that's my final answer :)

By troberts Date 03-11-2019 17:50

Thanks for the reply. Yes, I am taking the CWI Exam in April.

I completely agree with your answer E. The answer Key for my practice test tells me the Answer is C! That's such a strange answer that I have assumed that it is a typo. Problem is, another questions within the same test, on the same figures, also gives me a strange answer. I will post this questions to the general replies as well.

By SeeJeepGo (*)

Date 07-29-2019 15:04

Just be make sure anyone else is reading this for info.... there are some errors in here. first, unless my book is wrong, Page 84 in D1.1:2015 has the Prequalified joint B-L2c-S that you are referencing.

Also, your question asked about the "root face" which is 'f' in the sketch.

it is NOT the +1/16, -0 line (that is for root OPENING ' R' ) rather the +/-1/6 is for 'f'

Also, this question is a little misleading because even though there IS a tolerance stated for f, it also says "f= 1/4 MAX" and that MAX part is not always used in other diagrams, usually its a range, or just a single amount. Because of that little word, I don't believe you can't apply a fit up tolerance that would increase it MORE than 1/4". BUT if they had detailed it at 3/16" (because if you look at as detailed, they can't go more (0+) but can go less (f-) then you CAN apply the +/- 1/16" that is listed in as fit up, and make the face anywhere from 1/8 up to 1/4. Hope that helps anyone who is reading this.

By troberts Date 03-11-2019 18:06

Here is another practice exam questions from D1.1 part C with an answer that I cannot understand.

For the prequalified joint TC-U8a-GF, what is the permissible range for the root opening, as fit-up?

(Pg 91 of D1.1 2015 for TC-U8a-GF)

Possible Answers:

a) 0 - 1/8 inch
b) 0- 3/16 inch
c) 0- 1/4 inch
d) 1/16 - 3/16 inch
e) None of the above

My solution is as follows: R = 0 -+ 1/8, As detailed +1/16 -0, As Fit Up +1/16 -1/8. Therefore, the detailer could detail 0 to 3/16". As fit up allows another 1/16" on top of what is detailed. Therefore you can add another 1/16" to 3/16", which gives you 1/4".

My answer is C (0 - 1/4 inch).

Answer Key says that the correct answer is B (0 - 3/16 inch).... I really don't get it. Looks like they added 1/16 inch to the prequalified Root Opening Max.

By Steelslinger (**)

Date 03-12-2019 15:47

In this particular question, it spells out what it is looking for:

"For the prequalified joint TC-U8a-GF, what is the permissible range for the root opening, as fit-up?"

"As Detailed" is for the design engineer and/or drafter.

"As Fit Up" is for the welder/fitter. Welder/Fitter does not get to add the "As Detailed" tolerance.

TC-U8a-GF Root Opening is 0 to 1/8", Fit-up Tolerance is +1/16" and - 1/8", therefore, 0 to 3/16" is the correct answer for the question asked.

You have to make sure you understand what the question is asking prior to answering. Do not read into it, there is no 'between the lines' so to speak.

By troberts Date 03-12-2019 19:02

Thank you for your response.

So as I understand it, the key part of the questions is the "permissible range" statement. "Permissible range" is to be understood as follows:

Permissible Range (as fit up) - The allowable range the Welder/Fitter can deviate from the Prequalified Joint, assuming there is no Detailer.

That's a mouth full. But the reason I used so many words, is because if there is a detailer, and they apply their "As Detailed" tolerances to the max root opening, then the "As fit-up" tolerances can be applied to the "As Detailed" root opening. (additive)

Ex. Detailer adds their tolerance to the Root Opening, and now details a root opening of (1/8 + 1/16) = 3/16". Welder/Fitter fits the joints but has a root opening of 1/4 inch. This is acceptable because the Welder/Fitter has a +1/16 inch tolerance from the detail.