Definition - What does Pipe Segment mean?
Pipe segments are pre-determined lengths of pipes used in the trenchless pipeline industry for installation and rehabilitation of pipelines.
Pipes are manufactured in shorter segments for ease of transport and also for structural strength. The pipe segments are joined together one segment at a time at the site and installed within the excavation.
Trenchless installation methods such as pipe ramming, pipe jacking, horizontal directional drilling (HDD), and microtunneling require a precast, predetermined length of pipe segments. Some trenchless rehabilitation methods like slipliningand pipe burstingalso require pipe segments that are joined at the site and pulled into the host pipe.
Trenchlesspedia explains Pipe Segment
The length of pipe segments is determined by the contractor depending on the space available for the insertion pit. The material of the pipe also plays a role in determining the optimum length of pipe segments. Pipe segments are transported to the site and joined together using different welding or fusing methods as applicable for the pipe material.
Pipe Segments for Pipe Ramming
In the pipe ramming process, the lengths of pipe segments may vary between 10 feet to 60 feet, with the optimum length considered to be between 20 feet to 40 feet. As each pipe segment is installed, the ram is pulled back to its original position. A new segment is placed in the position behind the installed pipe and the ramming process is started again.
The pipe segments are either welded together or interlocking pipe joining systems are used that have mechanical press-fit joints which are quick to install and are strong. Welding of pipe segments takes a long time and needs to be strong enough to withstand the force from the percussive ramming that will push the pipe further.
Pipe Segments for Sliplining
In the sliplining technique of pipeline rehabilitation, pipe segments made of high-density polyethylene (HDPE) are preferred. The pipe segment sare joined by fusing adjacent pipe ends together that forms a very strong joint.
Polyvinyl chloride (PVC) pipe segments are fused and joined by pushing the belled ends together. In this method the pipe segments used are slightly smaller in diameter than the host pipe, allowing the pipe segments to be easily pulled in.
The annular space between the two pipes is later filled with grout to structurally stabilize the newly rehabilitated pipe.