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Up Topic American Welding Society Services / Certifications / Pre-Qualified Root Opening Tolerances - HELP !!!
- - By HJLBX Date 06-19-2016 20:29
It's unbelievable how difficult it has been to get a straight answer on this simple thing -- and the end result is that confusion = missed exam questions.

I've asked 3 CWIs and 1 SCWI, and have gotten literally 4 different answers...

The instructor at Son Set Consultants (SCWI) states: 

"Never add the tolerances together (as detailed  or as fit up) since they are separate and have no relationship.  Keep in mind that detailed drawing (as specified) and as detailed (tolerance) is two different items.  You are confusing these as being the same because of the word detailed."

Isn't the "As Detailed" range what the Engineer can specify on the drawings to comply with D1.1, Clause 3 ?

* * * * *

AWS' very own Visual Inspection Workshop, p. 11 states:

"The tolerances may be additive. It is possible to take the specified dimension and add both the detailers' tolerance and the fitters' tolerance. When taking the practical test, careful attention must be given to the wording of the question. If the question asks for a range of tolerance as fitup and detailed both tolerances are taken. If the question asks for the range of tolerances as fitup, only the fitters' tolerance is taken. If the question asks for the range of tolerances as detailed only the detailers' tolerance is taken. Take only those tolerances asked for in the question. "

* * * * *

What is the maximum size root opening permitted for a B-U2 joint both "As Detailed" and "As Fit-Up" ?

As Detailed

R = 0 to 1/8  |  Tolerance (+1/16, -0)

Minimum permitted to be detailed = 0

Maximum permitted to be detailed = 1/8 + 1/16 = 3/16

* * * * *

As Fit-Up

R = 3/16 (maximum from above)  |  Tolerance +1/16, -1/8

Minimum permitted at fit-up = 3/16 - 1/16 = 1/8

Maximum permitted at fit-up = 3/16 + 1/16 = 1/4
Parent - By HJLBX Date 06-19-2016 21:53
"As Detailed" = What the detailer specifies on the print.  To comply with Clause 3, Figure 3.2 the detailer can use the range of root opening as allowed in the "As Detailed" tolerance column.

"As Fit-Up" = What the fabricator can apply to the root opening detailed on the drawing.  To comply with Clause 3, Figure 3.2 the shop can use the range of root opening as allowed in the "As Fit-Up" tolerance column.

Engineer uses R in Groove Preparation column + tolerance to specify root opening on prints; the tolerance is groove prep latitude provided to the Engineer for root access, maintain overall dimensions, etc.

Shop uses R specified on prints + tolerance in "As Fit-Up" to account for challenges of fit-up -- which isn't absolutely a perfect process.

* * * * *

Max root opening possible at fitup = R in Groove Preparation column + max (+) tolerance in "As Detailed" column + max (+) tolerance in "As Fit-Up" column.

Is the above not correct ????????????????
Parent - - By pipewelder_1999 (****) Date 06-20-2016 00:08
There is a note in D1.1 regarding "tolerances" that should answer all of your questions. No need for a special interpretation or even a class to get a "straight answer"

Not sure how its worded in the current D1.1 as I don't have one with me but I am pretty sure its very similar. If you could look in yours and post it then it may help others.

AWS D1.1-2000

3.12.3 Joint Dimensions. Dimensions of groove welds
specified in 3.12 may vary on design or detail drawings
within the limits of tolerances shown in the "As Detailed"
column in Figure 3.3. Fit-up tolerances of Figure
3.3 may be applied to the dimensions shown on the detail
drawing. J-and U- grooves may be prepared before or
after assembly.

Let me know if this helps

Gerald Austin
Parent - - By HJLBX Date 06-20-2016 05:02
I got it...
Parent - - By pipewelder_1999 (****) Date 06-20-2016 13:51
is it worded the same ?
Parent - - By HJLBX Date 06-20-2016 17:55
Yes.  The wording in those sections has not changed from prior versions.
Parent - By HJLBX Date 06-20-2016 20:44
This is how I understand it:

The Engineer specifies the joint dimensions using the "Groove Preparation -> Root Opening | Root Face | Bevel Radius | Groove Opening" column.

The Detailer may - with the Engineer's approval - modify the joint dimensions on the detail drawings within the limits (tolerances) of the "As Detailed" column.

The Fabricator may fit-up the joint in the shop\field within the limits (tolerances) of the "As Fit-Up" column.

If the Engineer does not approve the use of the "As Detailed" tolerances on the detail drawings (detail drawing must use the specified joint dimensions exactly), then the Shop may apply the "As Fit-Up" tolerances to the specified joint dimensions.

If the Engineer does approve the use of the "As Detailed" tolerances on the detail drawings - and the detailer uses the tolerances (specified joint dimensions + tolerances) on the detail drawings - then the "As Detailed" and "As Fit-Up" tolerances will be additive.
Up Topic American Welding Society Services / Certifications / Pre-Qualified Root Opening Tolerances - HELP !!!

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