Use of Scan Pattern D

By EBA Date 07-21-2010 08:41

I am dealing with a customer that states our use of scan pattern D on an unground weld is not acceptable per D1.1 even though we are also using scan pattern E as required by code. Looking for some input.

By supermoto (***)

Date 07-21-2010 12:00

Not exaclty sure, but figure 6.21 note 1. states: Testing patters areall symmetrical around the weld axis with the exception of pattern D, which shall be conducted directly over the weld axes.

By jwright650 (*****)

Date 07-21-2010 12:09

Can you really get a good coupling on an unground weld?

I would also wonder if I saw someone doing that...whether or not they were getting much sound into the part due to the irregular surface of an unground weld cap.

By kipman

Date 07-21-2010 12:19

Sub-arc.

By jwright650 (*****)

Date 07-21-2010 12:26

A really flat cap on those welds, I suppose.

By kipman

Date 07-23-2010 13:01

Not always, but often good enough.

By EBA Date 07-22-2010 03:36 Edited 07-22-2010 03:40

Extra couplant is used to ensure the transducer is able to “float” above the roughness of the un-ground weld. Welds are Flux Core. Only reason for using this is to detect Transverse cracks that you do not see when using pattern E

By L51174

Date 07-23-2010 16:13

If you have qualified your procedure and proven that you can get sound into the weld..... trouble is, "floating" the transducer above a rough weld could mean that you never really have a consistant incident angle, among other things.

I suppose I would just give the customer what they ask for, and report it as such. Or better yet, continue to follow the procedure which was approved by your level III.

By 803056

Date 07-25-2010 17:18

I could be wrong (it happens with greater frequency that I will admit to), but if you are using scan D, the surface of the weld on which the transducer would be placed would have to be ground flush. I base my position on clause 6.32.2.1 of D1.1-2008. If the weld is not ground flush, scanning pattern E is required per clause 6.32.2.2. It would appear to me that there is a choice whether to use scanning pattern D on a ground weld face surface or scanning pattern E on an unground weld face surface.

The approved UT procedure should stipulate which scanning pattern is used and when each is used.

Best regard - Al