While the majority of a pipeline is underground, there are several types of supporting infrastructure that are constructed during a pipeline project. Compressor stations, facilities that maintain the pressure level within the pipeline, are built to support new pipeline projects, or existing stations are upgraded. Additionally, valve stations are built above the right-of-way along the pipeline, allowing operators to shut off sections of the line for maintenance or in an emergency. Metering stations are built along the length of pipelines, providing a measure of the flow of gas throughout the line.
To ensure pipeline integrity, welds must be x-rayed and the pipe hydro-tested. This process involves pumping in clean water, pressured above the expected MAOP maximum average operating pressure. Then, all water is removed and “pigs” are inserted into the pipe to clean it out. When the pigs eventually exit the far end of the pipe clean, then the line will be filled with dry air. Air compressors pump up the air, and the air is run thru a drier. The air will be sampled and tested for moisture content. When those parameters get low enough, the complete pipeline is filled with nitrogen to absorb more of the remaining moisture. Only then is the pipeline ready to transport natural gas.
Trenchless Crossing (Auger Boring)
Thrust Boring is a jacked and drilling method usually used road crossing, railways and structures. Due to the fact that Thrust Boring can be used with a variety of ground conditions from hard rock to wet soil and sand, this jacking and drilling technique is one of the most dependable and economical. Using an auger with a cutting head equipped within the steel casing, this is attached to the front of the Thrust Bore machine in the entry pit. Thrust Boring allows pipes to be laid easily with finite accuracy.
Trenchless applications for water, oil and gas, electric and fibre. The more traditional method of auger boring is still in play with many applications in ground support for under-crossings for rail and road construction applications.