Not every dance is pretty. Especially when your “partner” is another Alpha male better known as the installation supervisor!
According to ballroomdancers.com, the tango is “dramatic” and may have “stalking” or “sneaking” movements, which are “sometimes slow and slithery, and other times sharp and staccato”. Yeah, that pretty much describes the overtone as my “partner” and I “danced” around the liner several years ago.
The dance began on a slow note as the installer changed fusion-welding equipment for the shift (after successful field trials on non-production welding over several prior shifts). The dance remained fairly slow as I stalked my prey: suspect locations on which to place seam destructive samples. To my dismay, I could not find any suspect areas on the new machines, so I went to a more typical spacing, placing some destructs at the beginning, middle, and ends of seams.
Suddenly, the dance pace picked up. I was radioed that my first destruct failed field-testing—all coupons peeling apart like a monkey ripping open a banana. Shortly thereafter, I was radioed that another sample had failed. I quickly confirmed the sample numbers and checked my notes to see if there was a pattern. Both were on different machines, but both were located at the start of the seam. I had a pattern!
My partner and I alternated taking the leads in our dance—we all know how well two partners leading a dance goes—stepping on each other’s toes! He went over and cut the overlap off the first 4-7 feet of the weld, but while he was doing that, I marked more samples in the first 4-7 feet where overlap existed. It didn’t matter that I marked them there…he cut the lap on them anyways! At that point, we knew our dysfunctional dance was spiraling out of control, so we went back to a slower, more comfortable tempo. We agreed to evaluate seams with overlap remaining before we cut more overlap or before more destructs were marked. Suddenly, we looked like a graceful team again on the same mission!
The field-testing showed that the quality of the seam improved dramatically after the first four feet of the weld. For whatever reason, it took this amount of time for the machine temperature to stabilize and yield good welds on this particular material.
The solution for the rest of the shift was to deploy at least four feet of extra geomembrane beyond the tie-in, thereby removing this area from production welding (it would be trimmed off and used for repairs). As CQA, we measured the four feet from the beginning of every seam and marked the geomembrane—when less than four feet was trimmed off, we knew a patch was needed to at least that distance. Likewise, the installer opted to use their previous machines for welding the tie-in seams that shift, and return to the previous machines for the remainder of the project.
While our dance may not have been pretty, it was indeed effective. By the time the shift was over, the installer welded 7,750 lineal feet with these machines! What if I had not marked destructive samples until the next day? What if the installer was not cutting the samples the same day? What if the installer was not field testing the samples? When you look at the amount of seaming performed in a single shift you can quickly get a sense of the magnitude of the situation that was avoided.
Field Insights
As a lead CQA technician, it is important to always stay ahead of the contractor. This means prioritizing events, such as marking destructive samples. Some people mark samples before a seam is non-destructively tested, but my preference is to mark them after the seam has been tested, as this avoids a lot of complications, as well as allowing you to target any suspect areas located during the testing. It also keeps eager QC personnel from cutting out the samples before non-destructive testing is completed.
The turn-around on destructive test result feedback is critical to both CQA and the installer. The sooner an installer knows a problem or potential problem exists, the sooner they can act to remedy it and avoid problems of a larger magnitude.
