GPK's company-wide effort to manufacturing superior products


GPK has a multi-faceted approach to quality control:

  • • Materials

  • • People

  • • Processes



We start with high quality raw materials, including our proprietary resin blend for our molded products.


Quality is a team effort. Eighty percent of our employees have visual inspection responsibilities during the manufacturing process. Knowledgeable shift managers spearhead this frontline quality control, each having an average of 5-10 years of experience and some with 35 years of service.


GPK has been manufacturing PVC fittings for nearly 50 years. Our production steps have been fine-tuned through trial and testing. The defined standards we have in place for fabrication and molding help ensure the quality of our finished products.


Testing Lab


  • We regularly test our mainline Wyes, Tees and Tee Wyes in the following areas:

Heat Reversion Testing
A fitting is heated, then cut and a cross section is inspected for wall delamination.

Load Testing
With forces on the product, fitting integrity and deflection are evaluated.

Pressure Testing
We test to ensure performance of the fittings under low-pressure (10.8 PSI) applications.

Branch Bending
Using force against the branch of a fitting, we examine the point of bending or cracking.

GPK Products Testing Lab Pressure



GPK Products Testing Lab Pressure



GPK Products Test Notes



GPK Products Testing Lab Deflection