TPE Tubing Weld Testing

Introduction

The ability to aseptically weld tubing is critical to numerous biopharmaceutical manufacturing processes. Meissner’s BioFlex^® thermoplastic elastomer (TPE) tubing is designed to be both weldable and sealable, making it well suited for use in many applications requiring aseptic liquid transfer. This technical bulletin presents the results of BioFlex^® TPE tubing weld testing.

To assess weld integrity, tensile testing was performed on gamma irradiated and autoclaved samples of welded BioFlex^® TPE and C-Flex^® 374 tubing. Testing was conducted for BioFlex^® TPE welded to BioFlex^® TPE, C-Flex^® 374 welded to C-Flex^® 374, and BioFlex^® TPE welded to C-Flex^® 374 to account for a degree of versatility in established processes. Elongation, force at peak, and Young’s modulus were measured for each of the tubing sample sets.

Materials and Methods

Samples of ⅛” inner diameter by ¼” outer diameter BioFlex^® TPE (part no. 91T49G11) and C-Flex^® 374 tubing (part no. 374-125-2) were either gamma irradiated at 28.8-35.6 kGy or autoclaved at 121 °C for 60 minutes. Individual tubing segments were welded together using a Terumo^® SCD^® IIB Tubing Welder. The test method is adopted from ASTM D412 as an applications test assess force-at-peak, elongation and Young’s modulus. Tensile testing was conducted with an Instron tensile tester with a 500 N load cell. The initial jaw separation was set at 0.594 in. and a crosshead speed of 20.00 in. per minute was used for all samples. Tensile tests were performed on ten BioFlex^® TPE-to-BioFlex^® TPE welded samples and on five C-Flex^® 374-to-C-Flex^® 374 and BioFlex^® TPE-to-C-Flex^® 374 welded samples.

Results and Discussions

Tensile testing results of welded tubing are shown in Figure 1. for gamma irradiated samples and in Figure 2. for autoclaved samples. The results show that gamma irradiated samples were significantly weaker than welded tubing that was subjected to the autoclave cycle. This is likely explained by polymer cross linking of the TPE material caused by the high energy input of the gamma cycle. When comparing welds between the different tubing types, it is clear that the BioFlex^® TPE-to-BioFlex^® TPE welds outperformed the C-Flex^® 374-to-C-Flex^® 374, and the BioFlex^® TPE-to-C-Flex^® 374 welds. BioFlex^® TPE is an exceptionally clean tubing that does not contain any silicone oils, which may be attributed to its superior welding performance.

Conclusion

This testing demonstrates that BioFlex^® TPE tubing is well-suited for aseptic welding applications. The results indicate that whether gamma irradiated or autoclaved, BioFlex^® TPE tubing demonstrates excellent welding performance compared to the C-Flex^® 374, the existing industry standard for thermoplastic elastomer tubing.

Figure 1. Tensile test results of gamma irradiated welded tubing samples.

Figure 2. Tensile test results of autoclaved welded tubing samples.