WB started it’s first project late 2017 to build a pump station from HDPE, replacing galvanized fitting. With this expedition in to unknown territory came a lot of knowledge through trail, error, failure and success in the end. After all the trouble it was clear that a person needed to focus on HDPE welding to master all it’s tricks and headaches. This forced WB to buy our own welding machine and to train our technicians in the welding process to understand the limitations but mostly the possibilities of HDPE instead of galvanized.

Fun thing we learnt:

  • HDPE shrinks and expand due to heat, this causes bolt on flanges to loosen and requires tension for ±1-3 months after installation
  • HDPE is very sensitive to high heats. We are aware of 2 cases where a pump ran against a close valve and heated the water to a point the pipe melted!
  • It becomes very tricky to get a piece a precise distance but because of the properties of HDPE it is possible to make a piece shorter and stretch it a bit when tightening it with bolts (±5mm).
  • Butterfly and check calve have trouble opening in the HDPE stub flanges and thus needs to be machined before valve installation.
  • Long pieces begins to sag over time so supports are needed.
  • HDPE fittings cannot replace short galvanized fittings like concentric reducers where there is a big jump in sizes.
  • Putting saddles (for air valves or outlets) on short pieces of pipe does not work flawless but we are experimenting with welding sockets into a pipe and pressure testing it.
This year we will grow even more in the HDPE field by looking to invest in a larger welding machine. Currently we do welds from 40 – 250mm HDPE pipe. We are looking forward to growing in the HDPE field as the product should outlast galvanized steel and maybe even 304 stainless steel. Only time will tell.