7/27/2019 UT Versus RT

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UT versus RT 

by ashfaqanwer » 04 May 2010, 06:53

We have a situation at site.

At our waste heat boiler, the weld joints in P-1 material (P.No.3) were required to be

radiographed after undertaking PWHT. The weld joint is in 14" dia and 16 mm thickness.

What our construction contractor did is they radiographed the weld joints before PWHT in

order to just be sure about the joint clear of any repairs.

Now after about 03 months, the licensor imposed that atleast 10% of total weld joints shall

be radiographed or ultrasonically tested after PWHT. In order to comply with this

requirement, we used TOFD technique and found repairs in two joints out of 12 scanned.

Just to be clear we looked at the radiographs again for those welds and they were found

to be OK. We decided to conduct radiography of these two joints again just to confirmwhether the same joints were radiographed initially. And now we have found the results

which are OK again.

The defects in both the weld joints lie near the root of the weld (sub surface and

longitudinal) and they are larger than 100 mm in length. Radiography is not picking up the

same.

Now what should be the recommendation, should we go for the results what UT team is

providing or to rely on the radiographs? Should those defects be removed or would it be a

false call of UT?Ashfaq Anwer

ashfaqanwer@thepetrostreet.com 

ashfaqanwer 

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Re: UT versus RT 

by ndeguy » 04 May 2010, 14:06

Golden Rule: When re-testing AFTER PWHT, ALWAYS use the same method as used BEFORE

PWHT, otherwise its highly probable you will land yourself in the situation you are in now.

7/27/2019 UT Versus RT

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If this was ASME work was the TOFD carried out strictly in accordance with Section V

Article 4 Mandatory Appendix III? If not, throw the results away so as not to get into

deeper water. If yes (and I very much doubt it), whose bright idea was it to spend so much

money on using a highly sensitive method to re-examine radiograph quality welds?

To sum up, dont mention the TOFD to anyone, lose all records of it, do the 10% RT,

present the results to your licenser's representative and finito - job done..

ndeguy 

Posts: 4

Joined: 03 May 2010, 10:47

Area of interest: Metallurgy Engineering

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Re: UT versus RT 

by ashfaqanwer » 04 May 2010, 14:12

Great solution. I got it.

Actually TOFD was already available at site for inspection of many other weld joints and isbeing done according to ASME V Article 4.