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ASME B31.3 Progressive Sampling

ASME B31.3 Progressive Sampling

ASME B31.3 Progressive Sampling

(OP)
My understanding that progressive sampling in B31.3 work the following way:
1 Reject - 2 tracers
1 reject out of those tracer - 2 more tracers
1 reject out of those tracer - 100% NDE

what if in the first batch of sampling a welder has 4 rejects? The code does not exactly explain what to do in this situation.           

RE: ASME B31.3 Progressive Sampling

Fire the welder.

RE: ASME B31.3 Progressive Sampling

The Code does not and will not deal with welder productivity issues, only requirements for welders. Productivity is left up to the owner/user/contractor. I second the recommendation by stanweld.

RE: ASME B31.3 Progressive Sampling

My understanding would be that you would double the number rejected and do eight additional samples the second time around.

Or you could go directly to 100%, depending on the percent of rejects to passes in the batch.

Patricia Lougheed

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RE: ASME B31.3 Progressive Sampling

Per 341.3.4 (e) "if any of the items examined as required by (c) above reveals a defect, all items represented by the progressive sampling shall be either...". You must first define the items in the progressive sampling. If, for example, the first 4 welds "of the same kind" made by a welder are defective, terminate the welder and repair or replace all 4 of the defective welds. There is no requirement to test the welds made by other welders.  

RE: ASME B31.3 Progressive Sampling

You have not indicated how may the total batch is. If the welder only did 10 welds and four were rejects i would certainly insist that all of them are inspected. If his rate was 4 out of the first thousand then the person who waited until so many welds were complete should also be fired.  

RE: ASME B31.3 Progressive Sampling

REGRUMBLE hit it on the head.  Roll some heads.

As for B31.3 sample plan math: The 'batch' is the your production to date on the "Project".  Any single RT reject requires a resampling of 2 additional 'tracer' RT'd welds.  If EITHER of those fails, you must re-resample an additional 2 welds.  If either of those second pair of 'tracers' fails, that welder's production work requires 100%.  

Thus the intent of this Code is that if three samplings fail - 1st the random RT, 2nd either of the 2 tracers, 3rd either of the 2nd set of tracers - 100% RT or 100% removal of these welds [it's usually cheaper to just cut out the rest of this welders worek.  RT's are expensive]  So it only takes 3 rejected random RT's to engender the 100% 'death penalty'.  You have 4.  No further analysis required.  Time to start cutting out some welds, or send a big $$$ P.O. to an RT firm.

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