Each welder and machine makes a trial weld at the start of each shift, after long breaks and when conditions change, using the same sheet as the job. Coupons are cut and pulled in peel and shear on a field tensiometer, and production welding starts only when they pass. Settings are logged beside the results, so every seam can be traced to a proven setup.
Trial weld failed peel on the outside track, so nobody runs production until the wedge is adjusted.
Run a fresh trial weld when the sun goes in for long or the wind picks up; sheet temperature swings change what the welder needs.
Also heard as
- test weld
- trial seam
- start-up weld
- test strip
Related terms
Tensiometer
Portable tensile tester used on site to pull geomembrane seam coupons in peel and shear.
Peel test
Seam test that pulls the top sheet away from the bottom sheet across the weld to check how well they fused.
Wedge
Installer shorthand for the hot wedge welder, or for the heated wedge inside it.
Coupon
Narrow strip cut across a seam sample for peel or shear testing, usually one inch wide.
CQA
Construction quality assurance: independent monitoring and testing that a geosynthetic system was built as designed.