D1.1 fit-up tolerances

By r.doiron Date 01-26-2011 13:43

My question pertains to the prequalified joint fit-ups.

A question was posed to me with regards to Clause 3, Fig. 3.3, “Tolerances” as they apply to “As Detailed” and “As Fit-Up”. The question is when applying the “As Fit-Up” tolerances can you add the “As Detailed” tolerance as a cumulative total of tolerance. For example below for Joint Designation B-P1a, 1/8” T:

Is my “As Fit-Up” tolerance +/- 1/16” as stated or +1/8”- 1/16” because you are permitted to add the “As Detailed” tolerance to the Fit-Up tolerance. Paragraph 3.12.3 does not indicate any such thing though it is possible that I’m missing something and stacking the tolerances is in fact permitted.

I understand that any opinion you pose on the matter is to be considered “unofficial” but still appreciated nonetheless.

Thanks for the feed back.................

By 803056

Date 01-26-2011 16:31

The "as detailed" tolerances are the designer's perogative to increase or decrease the groove details by certain amounts. These increases or decreases are "usually" indicated by the welding symbol. If the groove angle, root opening, etc. is not indicated by the welding symbol, but the joint designation is listed in the tail of the welding symbol, the values for the groove details are the nominals listed in figures 3.3 or 3.4. The "as fitup" tolerances are added to the nominal values listed in the table.

If the designer has provided values for root opening, groove angle, etc. in the welding symbol, the "as fitup" tolerances are added to those values indicated by the welding symbol.

The fabricator/welder/inspector does not "stack" the "as detailed" and the "as fitup" tolerances unless the detailer has provided the "as detailed" information via the welding symbol. Only the designer can take advantage of the "as detailed" tolerance.

Best regards - Al

By pax23

Date 01-27-2011 16:48

Good answer.

See also past discussion here: http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=72993;hl=fitup

By Lawrence (*****)

Date 04-01-2016 17:34

Yes this thread is 1,892 days old

This is such a clean and brief explanation that it merits bringing to the front.

I used it today to help a friend from far away. I gave her a link to more of your work and credited you for my answer.

Thanks Again Al.

By 803056

Date 04-01-2016 19:38

Like everyone that plays on this play ground, we like to help each other when we can.

None of us got to where we are without help from someone. They were willing to share with us and they became our mentors. With a little luck, we can be mentors to someone else.

Best regards - Al

By kcd616