For butt welds, under which condition can lineup clamps be removed?

The correct answer is that lineup clamps can be removed when the weld is entirely complete. This is important because lineup clamps are used to hold the pipe sections in proper alignment during the welding process. Removing the clamps prior to the completion of the weld may lead to misalignment or distortion as the weld cools and solidifies.

Allowing the weld to be fully completed ensures that the integrity of the joint is maintained before any further handling is done. This practice is crucial, especially in high-pressure pipelines where joint quality is paramount for safety and efficacy.

The other options might suggest waiting for additional conditions such as cooling or checking bead quality, which are certainly important steps in assessing weld integrity, but they come into play after the weld completion. The main criterion for removing lineup clamps pertains directly to the completion of the weld itself.