The Art and Science of HDPE Fusion Welding in High Pressure Applications
The pipeline industry has been installing thousands of miles of High Density Polyethylene (HDPE) pipe with fusion welded connections. Failed connections are rare, but when they do occur it can be a costly and difficult operation to repair them. Butt fusion welding is not always done by trained and certified technicians, and without a way to monitor the parameters essential for quality welds, it will always be a guessing game if the joint is properly welded. For pipelines under pressure, it is even more important that the connections be done correctly.
This paper will discuss the use of a data recording device to monitor time, temperature and pressure for every fused HDPE connection on two high pressure sewage force main rehabilitation projects, along with the lessons learned. Of particular importance to the reader will be:
What’s critical for good welded connections.
What designers should know in specifying HDPE as a high pressure pipeline.
How to read data recording device output.
How to specify the testing and inspection of welded connections.
Good sliplining techniques to ensure joints are not degraded in installation.
Two case studies from Northern California projects in Monterey and Lake Tahoe will highlight the techniques used to verify welded joint integrity and what we learned that will benefit future project planning.