Equipment & machines
NO-DIG: pull heads and pipe pulling for underground boring
New pipelines are pulled under roads and buildings without a trench. How to choose and use pull heads so the pipe does not come off mid-pull.
The principle of NO-DIG
In underground boring (NO-DIG, trenchless), a pilot hole is drilled and the new pipeline is pulled back through the hole. PE pipe is ideal: it is tough, flexible and available in long lengths on a drum.
The loads during pulling are large. That is why a pull head is used, which distributes the force into the pipe wall instead of pulling on the pipe end.
Pull heads: how they work
A pull head with a mudtight/Weldon connection is secured inside the pipe with a threaded rod and clips that wedge themselves into the pipe body. The harder the pull, the better the head holds.
Choose the pull head according to pipe diameter and SDR class. Check that the pull head is approved for the pipe you are using, and inspect both the connection and the bolts before every pull. A pull head that lets go inside a bored hole is an expensive and difficult recovery.
Good practice during the pull
Keep the pipe free on the drum, use pull rollers and support it at the trench edge so the pipe does not scrape against the kerb. Backfill the holes with liquid clay (bentonite) or cement mortar after the pull so voids do not settle later.