UT on PQR's per D1.1

[bulldog2002]

When trying to qualify a PQR using UT inspection the plate/weldment failed, but when using RT the plate passed. Per D1.1 can the PQR still be used as a passing procedure with RT inspection passing but UT failing, all other visual, and mechanical testing passed.

 

[bulldog2002]

To clarify the above the, I have reviewed AWS D1.1 and have not found any specific verbage that states the RT test results cannot be used when the test shows passing compared to UT results that show failing on the same exact plate.

 

[Duwe6]

Absolutely not. You are in posession of test results that show FAIL. That cannot ethically or legally be turned into a PASS by cutting the test straps from the acceptable sections of the PQR plate.

Another case of RT missing something [probably Lack-of-Fusion] that UT will find. Sorry, but FAIL is FAIL.

 

[bulldog2002]

Duwe6,

I appreciate your input and you raise two decent points. However, I do not think this is a legal issue (I am not a lawyer so I could be incorrect but at worse it would be an AWS D1.1 violation). There are two factors I look at, the first being both contractor documents and AWS D1.1 specifically state that UT or RT may be used. The second factor is the destructive testing being done on the exact PQR weldment in question, if a flaw does not show up in: 4 side bends, 2 tensile pulls, macro etch, 30 CVN specimens (all taken in locations per AWS D1.1) all passing with mechinical properties required, I would ask why the PQR does "not pass".

 

[bernoullies123]

Generally speaking, (v2010) section 4.9.2 clearly indicates RT or UT. They do not go any further to define a rejection as you have encountered. The purpose of the NDT in the first place is to perform non-destructive tests prior to destructive tests so that any possible rejects will be picked up prior to the time and effort put into machining test pieces and finding out during destructive testing (note that this is also the view in the commentary C-4.9.2).

Now providing there was no agreement on the method (UT specific) per section 6.1.1, then with your visual + RT + Mechs = a good to go.

 

[Mr168]

"For acceptable qualification, the weld, as revealed by RT or UT, shall conform to the requirements of Clause 6, Part C." 4.9.2.2 - D1.1:2000

You are already in possession of test results that have "revealed" that the weld did not meet the requirements of Clause 6, Part C, and as such, would be rejectable.

 

[bernoullies123]

The boolean operator of the statement is 'or' hence if 1 value is true, then the statement is true. Another argument for an acceptable PQR.

 

[bulldog2002]

bernoullies123,

Thank you for your very valid points, you input is appreciated.

 

[bulldog2002]

Mr168,

Thank you for your input, it is appreciated and valued. Can you reference the up-to-date AWS D1.1, 2010 edition? I was not able to find 4.9.2.2 under Clause 6, section C in the 2010 version.

 

[bulldog2002]

Bernoullies123,

Sorry for the incorrect grammar, I meant to say: Thank you for your very valid points, your input is appreciated.

 

[Mr168]

Bulldog: 4.9.2.2 in Clause 4 2010 edition, my apologies.

2010 edition 4.9.2.1: Either RT or UT shall be used. Arguably, this indicates one or the other, not both.

 

[Kiwi2671]

Bulldog2002,
I have to agree totally with Duwe6.
Some welding codes actually allow mechanical testing to continue on a failed coupon if the defects can be shown as directly attributable to the welder and not the WPS parameters.
Unfortunately AWS D1.1 is not one of those codes - it clearly states in all versions that the weld must be sound over the full length.
UT is much more capable of picking up certain discontinuities than RT (as shown by your example)
If you had performed RT only and it passed you would be good to go - however,totally unethical to perform UT and when it fails just disregard the fact that you do not have a sound weld.
A defect is a defect no matter how it was discovered.
Regards,
Kiwi

 

[gtaw]

The stated purpose of NDT prior to destructive testing is to verify the welds are sound. The code permits you use either RT or UT, but the coupon has to meet the acceptance criteria of the NDT method selected.

It is the same as offering a child a vanilla ice cream cone or a chocolate ice cream cone. Given the choice, the child doesn't get to taste the vanilla and then the chocolate ice cream before making his choice. It is one of the other.

In a similar manner, you are given the option, either UT or RT. You don't get to use both methods and then select the method that passes the requirements.

The argument presented is like a situation I encountered several years ago; a welder performance test report listed “The weld looked like crap, but it pass X-ray”. The point is that if the test coupon didn’t pass VT it should not have been subjected to RT or bend testing. The coupon failed based on the VT criteria.

In this case the coupon failed UT, it should not have been subjected to RT or any further mechanical testing.


Best regards - Al