Using "As Fit-Up" Tolerances for PQR

Date 04-01-2019 18:28

Is this a State DOT project?
Do they have final say?
Will they allow you to weld on this project if you don't do the PQR their way?

If the answers are Yes to the first two and No to the last one, you guessed it, they win. You do it their way. Especially if their engineer is the EOR.

You have to read the DOTs specifications as a lot of times, they will list changes to the code that they demand you to follow. DOT specifications are to be considered the Law of the land.

By Matt F

Date 04-05-2019 14:50

Thanks for the reply - yes I plan to do whatever this state requires.

But I want to take that same test result and use it to qualify D1.5 work in other states, and that is the question. I guess as far as I am concerned this state PQR has slightly more difficult joint geometry than the D1.5 test. I will treat it as a D1.5 qualification to standard joint geometry and hopefully other states accept it. The worst thing that happens is they don't.

By Shane Feder (****)

Date 04-09-2019 13:25

Firstly, there is something very wrong with the numbers you have quoted.
I find it hard to believe that the DOT requires a joint that does not comply with D1.5.
I only have an old copy (2008).
Look at Table 5.3 (23) - any decrease in angle is not allowed.
So if you qualified on 30 degrees you certainly can't list 20 degrees on the WPS.

Maybe look at it from another direction - increase in angle is no problem to D1.5.
Qualify your PQR at 20 degrees if that is actually what DOT require.
Then write a D1.5 compliant WPS with 30 degree angle for your other customers,
Cheers,
Shane

By Steelslinger (**)

Date 04-09-2019 16:42 Edited 04-09-2019 16:48

The State looks to be requiring the SAW details for the B-U2-S joint design to be used.

Matt F - Which state are you working with? Can you also post what their spec is regarding WPS qualification?

I'm thinking you are qualifying in New York? 801b or 801d figures?

By Steelslinger (**)

Date 04-09-2019 16:53

If they qualify it at 25°, then they can still legitimately say it was qualified within tolerance having a -5° tolerance at fit-up. And seeing as Matt said that the DOT will accept 25°, then you'd be golden.

By Matt F

Date 04-09-2019 20:39

You got it - New York.

My problems were:
1. Assume only "prequalified" joint configurations will be used in production.
   Is it acceptable to take full advantage of the geometric tolerances to make the PQR easier to pass?
   I wasn't sure but now I think the general consensus is "yes".
   Take it a step further from "as detailed tolerances" and now add "as fit-up tolerances".
   What about one more step of using the positional tolerances? If it's a horizontal test can we tip the plate to the limit?
   I've seen it done in the past but I didn't really think it was correct.
   Now a welder performance test is different because the dimensions are actually shown on the figure.
   The shown dimensions and test position should be followed accurately, the welder should not be allowed to play games with tolerances.
2. What is the point of having separate "as detailed" and "as fit-up" tolerances if it's allowed to "detail" the test using the "as fit-up" tolerances?
   But I guess this doesn't matter if #1 is true.

My current plan: Go along with the above and have two drawings.
1. NYSDOT drawing:
   Root Opening: 5/8 +/-1/32 (made up tolerance)
   Angle: 25deg +/- .5 (made up tolerance)
   (I know this is acceptable)
2. D1.5 drawing:
   Root opening: 7/16 +1/4 -1/16
   Angle: 30 +10 -5
   "Note: NYSDOT test is 5/8" and 25deg, tests should be combined"

Thanks for the input and let me know if you disagree with anything.

By Steelslinger (**)

Date 04-10-2019 20:06

The welder cannot apply the 'As Detailed' tolerance, only the drafter/detailer can use that tolerance.

Welder can only apply the 'As Fit up" tolerance.

That is the purpose of the differential between As Detailed and As Fit up.

For the purpose of the D1.5 qualification, you are the detailer (as the one 'designing' the WPS). You detail it as 30° angle with a 3/8" root opening, the welder than fits it up and uses the tolerance to achieve a 25° angle with a 5/8" root opening. The fit-up test then meets the requirements of the NYSDOT test.

You can detail your NYSDOT qualification as 20° angle with a 5/8" root opening, the welder fits it up with a 25° angle and a 5/8" root opening.

As for position tolerance, that is something of a dispute among most CWIs. Proceed at your own risk in utilizing any, as some say there is no tolerance for positions on tests, others say otherwise. Your NYSDOT inspector/witness will tell you what they will allow.