CWI test clarification on prequalified joints

By BMCrules Date 11-06-2008 21:25

If asked about a Prequalified Weld Joint as fitup, do you always need to factor in as detailed too?

For example here are two conflicting practice questions and awnsers.

1) For Prequalified joint B-L2c-S, what range of the root face dimensions as fitup permitted for base metal thickness of one inch?

per the awnser book: 0 to 5/16
To get this awnser you need to factor in the "as detailed" too.

2) For prequalified joint B-U2-GF, the maximum root opening as fitup is?

per awnser book: 3/16 (if factoring tolerance of "as detailed" too it would be 1/4?)
To get this awnser you need to ignore the as detailed and just use the fitup tolerances

This devaition is confusing me and I need to have this issue solved becasue should be easy questions for me. Any help you give me is appreciated.

Thanks

By hogan

Date 11-06-2008 21:46

AWS prequalified joint details list two tolerances. One is "as detailed" this is in regard to detailing the joint. The other tolerance is "as fit-up" this is dealing with the allowances during fabrication. Hope that is what you were looking for.

By BMCrules Date 11-07-2008 00:24

I do understand that, but it does not help awnser the question. In some instances the "as detailed" is added on to the as "as fitup" tolerance. Is it just in the wording of the questions?

By hogan

Date 11-07-2008 00:26

The as detailed tolerance can not be used during fabrication as an extension of the as fit-up tolerance.

By csdenny (*)

Date 11-07-2008 15:39

BMCrules,

1) For Prequalified joint B-L2c-S, what range of the root face dimensions as fitup permitted for base metal thickness of one inch?

The key word in this question is "range". The only time that the tolerances for "as detailed" and "as fitup" should be combined is when the question mentions a "range" for either the root opening, root face or groove angle.

By hogan

Date 11-07-2008 16:37 Edited 11-12-2008 16:02

csdenny,
I have o disagree with you on this. As stated previously the as detailed tolerance is the only one you can use in fabrication. The as detailed tolerance is a tolerance that the detailer may use.

BMCrules,
Take a look at B-L2c-s. The face deminsion is listed as f=1/4" for over 1/4" to 1". Under tolerances, As fit-up you have + or - 1/16". By adding 1/4" and the tolerance of + 1/16" you get a max of 5/16".
For you second question, B-U2-GF your root opening is listed as 0 to 1/8". The tolerance for this is + 1/16", -1/8". So we add 1/8" and the +1/16" as fit up tolerance and now we have 3/16" max root opening.
Hope this helps.

By csdenny (*)

Date 11-12-2008 15:13

My mistake, I misread the question as I was a little pressed for time. The word "range" is used in the question, but since "as detailed" was not mentioned, the two tolerances are not additive.

You can and should add tolerances, but only when asked for a range and both "as detailed and "as fitup" are mentioned. Per AWS Visual Inspection Workshop, pg. 3-11.

By 803056

Date 11-16-2008 19:45

The questions regarding the prequalified joint designs usually states whether the "as detailed" is applicable.

If the questions asks for the range of root openings and there is no mention of "as detailed" in the question, then the range is the nominal plus or minus the dimensions of the "as fit-up".

If the question asks for the range of root openings for the "as detailed" condition, then only the tolerances of the "as detailed" are added or subtracted to the nominal value of the root opening listed.

If the question askes what is the range of the root opening for a specific joint detail for the "as detailed" root opening on the symbol is listed, i.e., 3/8 inch root opening, then the "as fit-up" tolerances are added or subtracted to the 3/8 inch dimension.

I hope this helps.

Best regards - Al