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Technical Discussions
Neil Tilbury1
United Kingdom, Joined Oct 2015, 1

Neil Tilbury1

United Kingdom,
Joined Oct 2015
1
17:22 Oct-06-2015
Root crack or misalignment

I had to ut an infill plate on a tubular connection recently and put myself through the mill whether to call a defect or not. Before I go on I will explain the details of what I inspected. full pen carbon steel weld with 2 different WT of 32mm and 35mm. The prep was a single v with the bevel on the 35mm material. The root gaps were 12mm to 14mm in places with the welder having to butter up the edges to about 6mm. By all accounts the welder was not happy at all with the task ahead. The whole job was a bit of a lash up. After welding was complete the cap was all ground off. I got to the job to ut it with the welder Standing by (a man I actually know of being a fairly good welder) first thing he said was scan this area as he said he'd had problems with the root and had cleaned out a root crack. Straight away it sent alarm bells ringing in my head. I put on the 0 deg first and picked up a split signal in that area so I automatically thought 'crack' both signals measured out at 32mm and 35mm which then made me think, is this the misalignment? I carried on scanning and picked the same signal throughout the full length of weld, which was about 900mm. I thought no could this all be cracked? I stuck on a 45 deg probe on and picked wide screaming signals consistently througout the weld from the thicker material. Bearing in mind as well that with a flushed cap your hitting a lot more of the root then you would with a cap. It totally baffled me and got my knickers in a twist and wasn't sure what to do as in call it a repair or put it down to misalignment. It was a tough call as the whole job was a nightmare in the first place. I ended up accepting it but now I'm questioning myself if I made the rite decision or not?

 
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Mario Talarico
NDT Inspector,
Italy, Joined May 2010, 423

Mario Talarico

NDT Inspector,
Italy,
Joined May 2010
423
13:11 Oct-07-2015
Re: Root crack or misalignment
In Reply to Neil Tilbury1 at 17:22 Oct-06-2015 (Opening).

Neil,
You were not really UT men if you have not beaten at least once the head in a few root pass! It happens.
There are many posts for generic geometries and misalignment. If the piece is still there and you want to comment on the specific case you should attach a scheme with the scans and accesses possible for any suggestions from some members.
However do not panic! "Picked the same signal throughout the full length of weld, which Was about ...", is an indicator of geometry. The zero-degree tends to lose the defects which open the thickness ... unless it is a cracks with inclination. Being ‘crack’ should have done the analysis eco-dynamic, rotational at least.

For the future do not get any such doubts: the old italian specification for line SAL-1, that I not attend for quite some time, it was written: in crack doubt...... is crack, and welding must be cut.
Greetings
mario

 
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Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
13:28 Oct-07-2015
Re: Root crack or misalignment
In Reply to Mario Talarico at 13:11 Oct-07-2015 .

"I stuck on a 45 deg probe on and picked wide screaming signals consistently througout the weld from the thicker material"

A root crack would have given a similar response from both 35mm and 32mm sides.

Did you have a 20dB beam profile overlay?

 
 Reply 
 

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