AWS A5.21-A5.21M:2011 pdf download.Specification for Bare Electrodes and Rods for Surfacing
6. Rounding-Off Procedure
For purposes of determining compliance with the requirements of this standard, the actual test values obtained shall be subjected to the rounding -off rules ofASTM E 29 or ISO 80000-1, Annex B, Rule A (the results are the same). If the mea-sured values are obtained by equipment calibrated in units other than those of the specified limit, the measured values shall be converted to the units of the specified limit before rounding off. If an average value is to be compared to the specified limit, rounding off shall be done only after calculating the average. An observed or calculated value shall be rounded to the nearest unit in the last right-hand place offigures used in expressing the limiting values for other quantities.The rounded-off results shall fulfill the requirements for the classification under test.
8. Retest
If the results of any test fail to meet the requirement, that test shall be repeated twice. The results of both retests shall meet the requirement. Material, specimens, or samples for retest may be taken from the original test assembly or sample,or from one or two new test assemblies or samples. For chemical analysis, retest need be only for those specific elements that failed to meet the test requirement. If the results of one or both retest fail to meet the requirement, the material under test shall be considered as not meeting the requirements of this specification for that classification.
In the event that, during preparation or after completion of any test, it is clearly determined that prescribed or proper pro-cedures were not followed in preparing the weld test assembly or test specimen(s) or in conducting the test, the test shall be considered invalid, without regard to whether the test was actually completed or whether test results met, or failed to meet, the requirement. That test shall be repeated, following proper prescribed procedures. In this case, the requirement for doubling the number of test specimens does not apply.
9. Chemical Composition Requirements
9.1 For solid drawn bare surfacing electrodes or rods, a sample of the fller metal or the stock from which it is made,shall be prepared for chemical analysis. Solid fller metal, when analyzed for elements that are present in a coating (copper flashing for example), shall be analyzed without removing the coating. When the fller metal is analyzed for elements other than those in the coating, the coating shall be removed if its presence affects the results of the analysis for other ele-ments. Rod stock may be analyzed prior to coating for those elements not added in the coating.AWS A5.21-A5.21M pdf download.