interpreting radiographic film of double vee weld(PJP)

By G.S.Crisi (****)

Date 10-11-2007 01:18

Yes. it is.
Giovanni S. Crisi
Sao Paulo - Brazil

By hogan

Date 10-11-2007 14:46

what code are you working to?

By krautkrammer (*)

Date 10-13-2007 17:10

We were working on AWS D1.1 code. We qualified a welding procedure for double vee weld(PJP) but the company who made the qualification test is don't want to include the radiographic test result. So what i just want to know is , how to interpret the radiographic film of double vee weld(PJP)? Do we need to consider the indication at the center of the weld(PJP)?

By hogan

Date 10-13-2007 19:46

you might want to have a level III in RT review the film, also by code you will need to be a level II in that method to interpt it. the solid black line in the center of the weld(unfused portion) will mask the portion of weld above and below that line. i have not found anything in the code that will not allow pjp welds to be x rayed, but it is not standard practice.

By CWI555

Date 10-14-2007 02:48 Edited 10-14-2007 02:51

Yes you do need to consider the indication at the center, but not for rejection.You can't determine the depth of penetration from the radiograph and the inherent dark line from the PJP's lack of full pen can be considered to mask. For PJP, it is not standard to use radiography for that reason. D1.1 2006 states:

4.8.2 NDT. Before preparing mechanical test specimens,
the qualification test plate, pipe, or tubing shall be
nondestructively tested for soundness as follows:

4.8.2.1 RT or UT. Either RT or UT shall be used.

You are required either or RT or UT. Therefore it should be evaluated before cutting which is more suited for the purpose. Since the line of Lack of penetration inherent in a pjp will show up rather dark in the center of the weld, it could and should be considered potentially masking of relevant indications in the weld center line. In short it is my opinion a joint like this should be UT'd instead. A good UT technician with proper reference blocks could give you an accurate assessment of this weld or one like it, but it will require special care and awareness of the reflectors inherent in a pjp, however; withstanding that, it is the only option for a 100 percent look at the volume of the weld.

If you've already performed the mechanical test, then you are either stuck with the RT or retesting/qualification. If you are stuck with the RT, then I suggest getting a Level III to review the film who has experience in that type of joint. I've had to train many level II's for interpreting this kind of weld and it's really easy to screw up the interpretation when all your used to is full pens, and even in that, there has to be a limitation put on the report due to the potential for masking in my opinion.

Regards,
Gerald

By NDTIII

Date 10-14-2007 03:37

I am not that familiar wth AWS D.1.1 but after looking through it it seems to me that the NDT requriements detailed in Section 6, PArt C only address CJP welds. Im not so sure you need to perform RT unless its specified in the specs.

It would be ludicrous to reject a weld for a discontinuity that was designed into the weld, but as CWI555 stated, it could mask other defects.

If the client requires RT, then I would say yes you must consider the LOP in the center of the weld. One thing I would suggest is that you take the length of the indicaton from the radiograph. Then cut various samples to get a vertical height and/or to determine that it is not a defect. Only the intended LOP designed into it. Alternatively, Your Engineering Department can then perform fracture mechanics to determine the acceptance. UT will only show you the same results for the LOP.

By CWI555

Date 10-14-2007 04:25

With the UT, the depth of penetration could be determined. Either method is going to show the lack of penetration in the center of a PJP. That must be taken into account for evaluation and as said, UT will be the only option for evaluating the weld metal without concerns of masking. Since D1.1 requires one or the other for qualification of a WPS the ludicrous part to me is using RT.

D1.1 6.16.1 Procedures and Standards. One of the ASTM standards in D1.1 requires adherence to is E-1032.

ASTM E 1032

7.2 Radiographic Coverage--Unless otherwise specified by
purchaser and supplier agreement, the extent of radiographic
coverage shall include 100 % of the volume of the weld.

Since the possibility of masking a relevant indication is not only likely, but near unavoidable should one be there, then RT, if a PJP, could not cover 100% of the volume of the weld. For that reason, I can understand why the company mentioned doesn't want to include the RT because to include it is to open themself to the very arguement I am stating here.

In my opinion, for what it's worth, the company doing the testing has screwed the pooch big time. This joint should not have been RT'd, any level III and most Level II's should be able to recognize the inherent problem with RT on a PJP.

Regards,
Gerald

By CWI555

Date 10-14-2007 04:28

Just for clarity, if the contract documents just stipulate D1.1 without specific mention of any changes to the testing procedures for WPS qualification, then it is a requirement of the code to either UT or RT the weld.