Test Piece Preparation, Dimensions and Welding of the Test Assembly
Preparation
The test piece must be prepared to the dimensions and joint geometry specified in the relevant part of EN ISO 9606. Preparation includes edge preparation (bevel angle, root gap, root face), cleaning, and fit-up. The welder must weld the test piece under conditions representative of production - same process, consumable, position and technique.
Dimensions
Typical butt test pieces are plates or pipes of specified thickness and length; fillet test pieces use T-joints or lap joints of specified leg length. The standard specifies minimum lengths and thicknesses so that the test is meaningful. Questions often give a dimension and ask whether it is acceptable - the answer depends on the table for that part and joint type.
Welding the assembly
- The welder must not use jigs or supports that would not be used in production unless permitted.
- Root pass, fill and cap must be made by the welder being tested.
- Tack welds: whether they are consumed by the weld or removed depends on the standard; if they remain, they must be sound.
- Preheat and interpass temperature must follow the WPS.
- The test must be witnessed by the examiner.
Traps
- Assuming the welder may choose position freely - the position is specified and recorded.
- Forgetting that the test piece must be identifiable and traceable to the welder.
- Overlooking that preparation defects (bad fit-up) are not the welder's fault but must be corrected before welding.
Rule of thumb
Prepare, fit, weld, mark, record. If it is not recorded on the QTR, it did not happen for qualification purposes.
Worked example
A 10 mm plate butt test is specified with a 60° included bevel and 2 mm root gap. The welder asks to increase the gap to 4 mm to make root fusion easier. This changes the joint geometry and is not permitted without examiner agreement; the test piece must reflect the specified geometry.