Which of the following is not true regarding the acceptability of a tack weld?

The statement that tack welds do not need to be made with a qualified or prequalified WPS is indeed the one that does not accurately reflect standard welding practices. In the context of welding, a WPS, or Welding Procedure Specification, outlines the necessary parameters for welding, including any required qualifications. For a tack weld to ensure structural integrity and meet safety standards, it is important that it aligns with the same rigorous criteria as other types of welds, particularly in critical applications.

The other statements highlight key aspects of weld acceptability. Tack welds being subject to inspection and needing to meet strength requirements aligns with the necessity to ensure that all welds, temporary or not, contribute to the overall strength and safety of the joint. Additionally, if tack welds fail inspection, they must be repaired to prevent any potential failure of the joint during subsequent operations or usage.

Understanding these principles is crucial for anyone being certified in welding, as they underline the importance of adherence to established procedures and standards in maintaining the quality and safety of welded structures.