How to: Thermoplastic Membrane Test Welds

​Test welds are an important part of welding thermoplastics whether they’re used for roofing, tarps, pools, tunnels, landfills, or tailings ponds. Welds should be tested first thing in the morning and several times throughout the day to ensure that environmental changes are not compromising the strength of your welds. 

How to Test

Testing a weld is simple.

• Prepare several test welds by varying speed and temperature. Change only 1 parameter per test. Be sure to record each set of parameters; the simplest way to do this is to write them on the material. 
• Allow the weld to cool to ambient temperature.
• Cut strips approximately 1 inch wide.
• Perform a peel test by pulling the layers apart.

What to Look For

• Look for the material to delaminate
• The two pieces should not come apart cleanly
• The material should delaminate, leaving part of one piece stuck to the other 
• You should be able to see the scrim or webbing of the material
• If a full delamination is not seen, change the temperature or speed setting and try again

Why Testing is Important

It is recommended that test welds be done multiple times throughout the day. Changes in the environment such as air temperature, cloud cover, and material temperature all affect weld parameters. Testing welds multiple times ensures that your seams are completely sealed and there will be no leaking in the future.

Have questions? Contact your Technical Sales Representative to discuss your application.

Originally published: 06/24/2015​