This article provides brief information about ASME Section IX Tensile Test requirements. The procedure qualification in ASME Section IX requires two tensile tests, two face bend and two root bend tests. The test specimens dimensions must be based on Fig QW-462.1 (a) thru QW462.2 (e).
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The ASME Section IX provides minimum specified tensile strength (MSTS) for each material. For instance, the SMTS for SA 516 Gr. 70 is 70, 000 PSI and you can find this value on the QW-422
The test specimens should be break less than specified minimum specified tensile strength in weld or weld interface. However, if it breaks in the area out of weld or weld interface will be acceptable 5% below the minimum specified tensile strength.
For example, if your test specimen is SA 516 Gr 70 and breaks at the place out of weld and weld interface at 66500 PSI (MSTS is 70,000 PSI), the test will be acceptable. The cooling rate in the vicinity of weld line will be slower than the weld metal, and this causes the area out of weld being weaker (Heat Affected Zone). The lower cooling rate it means greater grain size, and the bigger grain size means less tensile strength, and this is why the code is providing this 5 % concession.
The tensile is calculated from dividing of applied load to the test piece cross section. Both tensile test specimens must pass the MSTS requirements to be acceptable. When you are checking the submitted Procedure Qualification Record, you need to verify the tensile test results.