NDT Extend of Testing

By thinhnguyen Date 08-29-2013 10:53

Dear Sirs,
With respect to the provision 6.15 of AWS D1.1 that just mentions 03 categories of test (including Full Test, Partial Test and Spot Test) and that does not mention the RANDOM Category.
In my project, the specified NDT Extend is belonged to RANDOM Test Category (Such as 20% Random NDT), then I still don't know that the such Extend of Testing is "20% of weld length" or "100% Weld length of 20% of weld joints" according to AWS D1.1?
Please support me to clarify this issue!
Look forward to hearing from you soonest,
Thank you very much for your kind supports,
Best Regards,

By 803056

Date 08-30-2013 01:45

When in doubt, ask the Engineer/Owner that is responsible for developing the project specification..

Al

By thinhnguyen Date 08-30-2013 03:05

Dear Sir,
I have discussed to my owner for using the RANDOM NDT extent by means of specified percentage per number of weld joints. But they said that AWS D1.1 provides RANDOM NDT extent shall be per weld length, therefore I would to seek your advise in order for me to fully clear the definition of RANDOM NDT Extent based on codes provided. (only for my knowledge)
By the way, i also would to know how does the code provides penalty requirement for NDT rejected welded joints in case of Random NDT extent which is applied.
At all, my concern is only for my knowledge.
Look forward to hearing from you at the soonest.
Thank you very much for your kind supports,
Best Regards,
Thinh Nguyen

By 803056

Date 09-01-2013 03:27

Based on AWS D1.1/D1.1M:2010, there is no random inspection/testing.

The extent of testing defined by D1.1 includes Full Testing, Partial Testing, and Spot Testing.

D1.1 specifies Progressive Testing when a weld fails a Spot Test. The code defines what a Progressive Test is. However, when Partial Testing is required, the failed weld is simply repaired. No additional testing is required when Partial Testing specified, i.e., there is no additional repercussion. The Owner must specify Progressive Testing if he wants to impose a consequence for failing a Partial Test. The Owner must also define “Progressive Testing" in the project specification.

It has been my experience that the inspector performing the testing selects the specific joints or locations to be tested if or when the Owner does not.

It is common for codes to provide a framework for testing, but it is up to the Owner's Engineer to provide the level of detail required by the code plus any additional information needed to perform the work. A corollary to the NDT dilemma; a structural design code provides basic criteria the engineer has to take into consideration such as allowable stress, permissible beam deflections, floor loads, etc., but it is up to the engineer to develop a viable design that meets the Owner's needs. In a similar manner, the code provides the basic information about what must be tested, but the engineer must define the extent of NDT (other than visual inspection). Failure to do so is akin to the designer saying, "Put a beam there." without defining the size, length, or type of end connections required.

Best regards - Al