Pipelines are mainly used to transport gas, water, oil in petrol and gas industry. Designing and installing a gas pipeline is a lengthy, detailed and complex job, which cannot be completed overnight. The whole construction period can take up a long period of time, with a specialized and qualified working team. Great effort should be taken to safely finfish the project while maintaining complete environment condition and minimizing impact on the land owners. Today let’s take a close look at the construction of pipelines.
The construction period can be simply divided into 3 parts, namely pre-construction, while-construction and post-construction. 
Before the construction begins, the company should obtain the legal rights to the land along the proposed route, called a right-of-way, from landowners. Once the proposal is approved and a route is developed, the route is then marked with stakes.
Vegetation is removed from the right-of-way and the topsoil is removed and stockpiled for future reclamation. The crews install fences along edges of streams to prevent erosions of the disturbed soil. The right-of -way will also be graded so that the construction equipment will operate safely.
When the right-of-way is prepared, the crew uses backhoes or trenching machines to excavate a pipeline trench and place the excavated soil to the side.
Various lengths of pipes are moved from stockpile sites to the right-of-way. They are laid out eng-to-end, ready to be welded.
A pipeline may meet special terrains, such as lakes and hills, in which a straight pipeline cannot successfully be places. To solve this problem, a special pipe-bending machine will be used to bend some pipes to fit the shape of the land.
Welding is a technique used to melt metal and join each joins of the pipes.This step will be repeated several times until joints of the pipes are joined together to form a pipeline using either manual or automated welding process. Both methods are inspected and certified to guarantee high quality of the welding.
It is necessary to coat the pipeline both inside and outside in order to prevent it from corroding or rusting. In some rugged areas, some specialized external coating, such as abrasive resistant fusion bond epoxy, will be used to alleviate the effect of abrasive condition and provide an external protection.
Before the pipeline is lowered into a trench, the integrity of the coating should be closely inspected. If any defect is found in the coating, a repair coating will be applied to fix the problem.
The pipeline is lowered into the trench using heavy lifting machines called side booms. Great care should be taken not to damage the external coating and the pipeline itself.
Once the pipeline is placed in the trench, valves and other fittings will be installed on the pipeline. The valves are used to block off certain section of the pipe. Then, the pipeline is carefully backfilled with the excavated soil.
A variety of methods are adopted test the pipeline,making sure it can withstand extreme pressure, while maintaining long-term reliability and safety.
The right of way will be reclaimed and contemporary facilities set up during the construction process will be removed; the area will be restored as close as possible to its original condition.
The pipeline serves as a vital link that delivers natural gas and oil. Thus, the construction of pipelines is certainly of great significance. The pipeline construction is a highly-specialized technical work, requiring great efforts and rich expertise. Only by following proper steps and working procedures can you get the pipelines well built.
