While HDD and pneumatic piercing tools both offer some benefits of trenchless methods, HDD operations may not provide cost savings due to the large equipment requirements and need of highly qualified crews. Piercing tools are often more economical yet do not address the concerns of leaving the abandoned line in the ground.
Often the most expensive solution is traditional ‘dig-and-replace.’ Larger excavation and subsequent restoration requirements increase the cost of a replacement project. Additionally, excavation is not always feasible in congested site conditions, such as certain urban downtown areas.
A more economical solution is inserting the steel line with a new plastic pipe of a smaller diameter. The insertion method eliminates much of the excavation otherwise required but is not always viable as it requires the existing line to be oversized in order to undergo a reduction in Internal Diameter (ID) without negatively affecting its ability to deliver the necessary level of gas to the customer. Insertion also inherently creates an annular space around the new line which creates the possibility of trapping leaking gas within the annulus where it could build up and travel into the building. In addition, many times a copper or steel pipe may have a bend or small kink in the line preventing a smaller pipe to be inserted inside. For this reason, not all operators allow the insertion method to be used within their inventory.
While these existing technologies have proven effective, certain site conditions make their use costly, inefficient, or infeasible, presenting a need for innovative alternatives.