I would interpret the requirement to mean that if the weld is less than 1.5 meters in length, one set of readings would suffice for each 1/2 meter of length. If the weld was 3 meters in length, nine sets of readings would be required. In other words, each weld would require at least one set of readings if the weld was less than 1/2 meter (roughly 19 inches). Another way to say it is I would prorate the number of tests, but each weld would require one set of readings.
Al
By MBSims 
Date 08-14-2016 15:43
Edited 08-14-2016 15:50
Only your customer can say for sure what they intended. If you make the wrong assumption without asking the customer, you may be liable for the cost of additional testing and rework. If the client inspector is saying they want 3 measurements at 120 degrees apart, then that is what you need to do. You may want to document their position in case it comes up again in the future and a different inspector has a different opinion. We use a "Request for Information" (RFI) form to clarify the customer's position. If they agree or don't agree, they will provide their response in writing.
I concur with the previous opinions.
The RFI should be explicit. Are the three individual tests comprised of only one direct reading each or an average of several readings of each test spot? Does the area surface to be tested required to be sanded? Sanding (finish) criteria? Fischer Feritscope calibration frequency? NDE training and/or qualification of technician? Is there an "approved" written testing method that includes a confidence index or at minimum, an exclusion for "outliers?"
Robert
Dear Al
In Your Response " One set of Readings " Does it mean Ferrite Test Readings required- 2 readings -HAZ and one on Weld?
To my understanding, sole purpose of Ferrite Test is to measure Micro-content on Weld.
Thanks
Here is a sample of our test results on a 2205 project.
Robert
Ouch!! Point count method!! Is this per NACE MR0103 or API?
My apologies to the OP for straying to a side topic.
To answer MBSims; this is a Client engineering specification. As Al has pointed out in similar threads (search 2205), FN is much more accurate than FE% when analyzing ferrite in the upper ranges.
Robert
I would disagree with some of the previous opinions. The client is not the ultimate arbiter of the Code. If the Code says one thing and the client another, or wants something more, that is fine, but it better be in contract documents up front or I would tell, diplomatically of course, the client inspector to take a running back flip. He isn't' getting a Ferrari if he is paying for a Volkswagen.
I don't think anyone was suggesting that the client be asked to clarify Code requirements. The ferrite measurements the OP was aksing about are customer spec requirements. B31.3 does not require ferrite measurements at all.
Nalla,
It would be for weldmetal,
I would like to see a test done on a production not practically possible.
It would be 1 test result every 0.5 meters of welding.
the test result may be based upon more than 1 reading e.g an average of 3 readings. This should be clarified.
