Quality testing in plastic welding is important to ensure the durability of the thermoplastic installation. The strength of the weld can be measured in Newtons by the use of bending equipment, which measures said strength by means of a calibrated cell. To ensure the accuracy of the measurement, it is necessary to cut a sample of the welded material (pipe or sheet) with certain dimensions. Once the sample is placed, the equipment applies pressure on the welded material and measures the strength until the material is either broken or bent to a specific angle that depends on the properties of the material.

Quality testing can be carried out by means of a spark tester to verify the possible leaks in a surface covered with a geomembrane or a sheet. There are several types of spark testers available for leak testing. The spark tester can adjust to the different thickness of the plastic coatings. In some cases, it is necessary to put a copper wire before performing the welding with either an extruder or a heat gun so that the tester is able to identify any pore or hole in the welded surface.  In the same way, there are spark or arc testers that do not require the copper wire to check for leakages in plastic-coated surfaces. This equipment has a wire that is grounded outside the coated surface, so that it only requires a conductive material such as earth, concrete, etc., underneath the plastic. To ensure a job well done and avoid dangerous leakages or economic losses due to these leakages, it is of vital importance to perform these types of testing.