Hello,
When qualifying welders to AWS D17.1, it is important to specify 't', the thickness of the thinnest plate, as this is used to determine the qualified thickness range.
My question is, if the certificate of conformity that comes with the test plate material has a tolerance on the thickness, e.g. 0.050" +/- 0.003", which value should be used as 't'?
1) Take the specified thickness (which is in the middle of the range), i.e. 0.050".
2) Measure the actual parts to be welded, and record this as 't'. More accurate, but then the qualified range could vary from welder to welder; one might use a 0.047" plate and another a 0.053" plate, for example.
Thank you for your help.
This may seem over simple..
Measure with a calibrated sheet metal gage rather than calipers or a micrometer.
Wow, you're really driving tacks there. Is this for procedure qualification, or performance qualification? The welder will be qualified to work on material thicknesses of .67t to 4t. The procedure qualification should employ materials likely to be used in production, so your thicknesses are going to be similar. +/- .003" isn't going to make any difference in either case. Heck, thermal expansion and variables in the material surface could eat up that kind of tolerance.
Topic American Welding Society Services / Certifications / D17.1 - how to determine 't' (test plate thickness)
