Posted on September 26, 2017
While fusion has traditionally been seen as the “gold standard” in strength and reliability when it comes to joining high-density polyethylene (HDPE), empirical data suggests a change in thought is warranted.
Historically assumed to be as strong as the pipe, the integrity of fused joints is at the mercy of many variables. A fused joint is only as good as the technician operating the fusion machinery and tediously following a detailed process that leaves little room for fluctuations in environmental conditions. Surface contamination, windy, hot, or cold conditions, heating plate temperature control, and fusion times can all impact the integrity of a fused joint – and there is no visual or effective non-destructive method to inspect the quality. According to Dr. Chris O’Connor’s Polyethylene Pipeline Systems – Avoiding the Pitfalls of Fusion Welding, the existing non-destructive testing methods, such as radiography and ultrasound, “cannot reliably detect key issues that are known to affect HDPE joint quality such as fine particulate contamination, cold fusion in butt welds, or misalignment and contamination in electrofusion joints”. Once the fusion process is completed, only time will tell how well the joint is fused. To ensure the integrity of a fuse in the absence of any effective testing, equipment must be regularly inspected and properly maintained to record accurate temperatures and calculate appropriate heating and cooling times. A culture of continued training and professional development is crucial, limiting equipment operation to only those installers that have been trained and certified, and relying heavily on user competency to ensure that the processes are strictly followed.
Unlike fusion, Victaulic’s Refuse-to-Fuse™ mechanical joints use simple tools for installation, leaving virtually no room for error. The easy four-step process can be completed regardless of weather conditions and provides visual verification of correct installation – and joint integrity. By simply visually confirming metal to metal contact at the bolt pad, the installer can verify a leak-free seal. Ultimately, high-quality joints are not only easier to achieve using the Refuse-to-Fuse system, but also easier to verify than a fused joint.
Refuse-to-Fuse mechanical joints are fully restrained joints that have been proven to meet or exceed HDPE pipe pressure ratings, allowable tensile loads and bend radius recommendations of a fused joint. This means you can push, pull and drag your pipe like any fused solution:
Refuse-to-Fuse is specifically designed with strength and durability in mind. In fact, under extreme pressure tests, Victaulic mechanical joints have been shown to outlast HDPE pipes – meaning the pipe itself will fail under pressure before a properly installed Refuse-to-Fuse joint:
To learn more about Refuse-to-Fuse system performance, click here.