A pipeline is a system of pipes designed to carry fluids such as oil, natural gas, or other petroleum-based products over long distances, often underground. It is a very important part of the modern civilization that has now been used for millennia for the movement of water.
Pipelines typically cost more than roads or open channels. It takes years and requires many surveys and studies and plans to be completed to develop a comprehensive plan that addresses the societal, developmental, environmental and safety considerations necessary to build the pipeline.
However, they can offer reductions in cost based on shorter and more direct routes than roads or open channels. Construction of pipelines, especially for large scale water-supply or petroleum projects, are large multi-disciplinary activities which involve the investment of large amounts of cash and other resources.
There are different types of pipelines classified on the basis of manufacturing material, transported substance, and function of the pipes.
Types of Pipelines
Based on Pipe Manufacturing Material
Selection of materials for pipes is based on the design of the pipeline, internal and external forces, jointing and laying techniques, durability, impermeability and the frequency of maintenance.
1. Steel Pipeline
Steel pipes are employed for the water pipelines. Large diameter pipes can be manufactured from steel and can be extended over large distances.
2. Cast Iron Pipeline
Cast iron pipes are mostly produced from gray cast iron for which coatings and linings are applied so as to improve corrosion resistance. These types of pipes have been widely used in the past.
However, today, ductile iron pipes which are superior to cast iron pipes are being widely used. Such a pipeline type is suitable for the transmission of water, gas, and sewage.
3. Plastic Pipeline
It is generally used for the transmission of water over long distances. Plastic pipes have great resistance to abrasion, chemical influence and are easy to handle. Added to that, their light weight makes it easy for the workers to lay and align as per the need. However, they have low tensile strength and show poor performance during temperature fluctuation.
4. Concrete Pipeline
Concrete pipe is manufactured from welded sheet steel with surfaces and concrete. It is particularly suited to large diameter pipelines extending over great distances. Concrete pipes are an appropriate choice for the transmission of water.
Based on Substance Transported
5. Water Pipeline
It is employed to transfer water from treatment plants to buildings. Generally, such pipelines are installed underground few meters beneath the cities and streets based on frost line of the location and the need for protection against accidental damage. These pipes can be produced from steel, ductile-iron, and concrete.
6. Waste Water Pipeline
They are used to transport wastewater which is composed of a high percentage of water and a small percentage of solid wastes. These pipes can be manufactured from concrete, PVC, cast iron, or clay based on the pressure in the pipe and other conditions. Pipe sizes are controlled by the type of materials and pressure in the pipe.
7. Petroleum oil Pipeline
It is manufactured from steel for which external coating and cathodic protection are applied to decline external corrosion. Oil pipelines are joined together by welding. There are two types of oil pipelines, namely: crude oil pipeline- which transports crude oil to refineries, and product pipeline- that carries products like gasoline to the market.
8. Gas Pipeline
Pipelines are the only practical means of transportation of natural gas over land since the other methods such as truck and train are considerably expensive.
Gas collection and transmission lines are made of steel whereas most distribution lines use flexible plastic pipes, which are easy to lay and do not corrode.
9. Slurry pipeline
is a mixture of solid particles and a liquid, usually water. The mining industry and dredging utilize slurry pipeline.
It transports oil and natural gas from offshore oil and gas wells to overland pipelines. Barges in less deep water and ships in sea are used for the installation of submarine pipelines.
Based on Pipe Function
10. Transmission Pipeline
It is used to transport crude oil, NGLs, natural gas and refined products for long distances across countries and continents. Transmission pipeline sizes are mostly greater than 25.4cm (10inch). Corrosion, defective welding, seam failure, and material failure are common causes of transmission pipeline damages.
11. Distribution Pipeline
It is used to transport natural gas to homes and businesses. The size of distribution pipes ranges from 12.7 mm to 152.4 mm.
12. Collection Pipeline
Collection pipelines carry oil or gas products from the wells in the ground to the oil batteries or natural gas processing . Their diameter varies from 101 mm to 304 mm.
Based on Method of Construction
Types of pipelines based on the method of construction include underground pipelines, above-ground pipeline, elevated pipeline, offshore and underwater Pipeline.
Pipeline Construction Phases
The construction of pipelines can be done keeping the following points in mind:
- Route survey.
- Clear the area, Fig. 10.
- Ditching or trenching. Fig. 11.
- Transporting the pipes, fittings, and other materials to the site.
- Stringing the pipes along the trench, Fig. 12.
- Bending steel pipes in the field to suit topography of the site.
- Applying coating and wrapping to steel pipes.
- Joining pipes together either before or after they are lowered into the trench, Fig. 13.
- Examine the pipe for any welding flaws or leakage at the joints
- Covering trenches by soil and restoration of the land to its original appearance, Fig. 14.
For longer pipelines, construction is done in segments so that one segment of the pipeline is completed before the construction proceeds to the next. This minimizes the time that any given place is disturbed by construction activities.