How does pressure testing of fusion welds function?

Pressure testing of fusion welds is a method used to determine the integrity of the welds by assessing whether they can withstand the specified pressure without leaking. When a gap of unfused membrane is placed under pressure, it allows for the evaluation of the welded joints by detecting any potential failures in the fusion process that may not be visible during visual inspections.

This technique focuses on the fact that if any gaps or weaknesses exist in the weld, they will be exposed when subjected to pressure. It is a practical application in many industrial settings, particularly in landfills where the integrity of containment systems is crucial to prevent environmental contamination.

Examining the other options illustrates why they don't align with standard pressure testing practices for fusion welds. Submerging the weld area in water can help identify leaks visually but does not apply pressure in the same manner as placing an unfused membrane under pressure to assess the weld's strength directly. Applying heat until the weld melts does not test an already completed weld but instead refers to the welding process itself. Utilizing chemical agents for leak detection can augment inspections but is typically not part of the standard pressure testing procedure for weld integrity.