How to build the long-distance oil and gas pipeline
With economic and social development, domestic oil and gas consumption, especially natural gas consumption, has maintained a rapid growth trend, and oil and gas pipeline construction is ushering in a golden period of development. In recent years, to meet the demand, the scale of China’s oil and gas pipeline network has been expanding, and the construction and management level of oil and gas pipelines has been substantially improved. The establishment of the national pipeline network company will accelerate the pace of oil and gas pipeline construction in China.
After the feasibility study, special evaluation, approval and other preliminary work, and then the completion of the preliminary design of the pipeline, construction drawing design, selection of business, obtain construction permits, etc., it will enter the construction phase. So, how is the construction of the long-distance oil and gas pipeline constructed?
The design representative hands over the design control (corner) piles to the construction unit at the site and checks the pile number, mileage, elevation and corner angle.
Measuring and placing lines
Based on the design information such as line plan, longitudinal section, line control stakes, etc., the surveyor uses special instruments to determine the location of the centerline of the pipeline installation along the line and draws the boundary of the construction operation zone.
Construction work zone cleaning
Use bulldozers and other construction equipment to level the construction zone and remove trees and other obstacles in the zone. The width of the pipeline construction work zone is generally between 12-32 meters. For non-mechanized construction lots in mountainous areas, the width of the work zone can be appropriately reduced according to the terrain conditions.
Steel pipe transportation
The steel pipe will be transported from the pipe factory or the train transfer station to the construction site by road, in which the steel pipe transport needs to use special transport vehicles, and the loading and unloading of the steel pipe also needs to use a special pipe sling, and the steel pipe and the frame and the two steel pipes must be separated by soft materials such as rubber sheets.
Pipe trench excavation
The long-distance oil and gas pipeline is usually laid in the ground, which requires trench excavation process, the depth of the trench is generally between 3-5 meters, and the width of the bottom of the trench is generally less than 3 meters. When the pipeline crosses the river, it often adopts methods such as large excavation, directional drilling, shield tunneling and crossing, etc. The specific laying method should be considered according to the size of the river and geological conditions.
The steel pipe in the operation zone will be placed to the construction position, which generally requires the steel pipe to be connected at the beginning and end and distributed in a jagged shape, and the steel pipe also needs to be placed on a flexible object, and should not touch hard objects such as stones to avoid damage to the pipe.
Steel pipe assembly, welding and weld detection
This is the most important part of the long-distance pipeline construction process, in which the alignment process is the preparation work for the welding process, and the two pipes need to be aligned, and then the two pipes are clamped together with the alignment device. After the assembly process is completed, the welding process can be carried out! After welding, the weld seam needs to be inspected to ensure the quality of the weld.
At present, the welding process mainly includes manual semi-automatic welding and fully automatic welding, and the newly-built pipelines such as the China-Russia East Line focus on promoting the application of fully automatic welding process.
Pipeline patching and mending
After the welding of the pipeline is completed, the anticorrosive layer of the pipeline interface needs to be patched, and after the operation is completed, a comprehensive quality inspection is required to ensure that the pipeline can operate safely and smoothly after it is put into operation.
After the completion of welding, non-destructive testing and repairing, review the depth of the trench to ensure that it is in accordance with the specifications, remove the foreign objects that damage the anti-corrosion layer in the trench, and then lower the completed welded pipe to the bottom of the trench with special lifting equipment as soon as possible.
This is the last process to ensure the burial depth of long-distance pipeline, and also an important factor to ensure the quality of pipeline installation and operational safety. During the backfilling process, communication fiber optic cable is laid in the same trench as the “highway” for intelligent pipeline remote monitoring information transmission.
Pipeline cleaning, sizing, pressure testing
Adopt pipe cleaning ball (device) to clean the pipe and remove the debris in the pipe; adopt the diameter measuring plate to measure the diameter, after the measuring plate passes through the pipe section, no deformation and wrinkles are qualified; adopt water (gas) medium to fill the pipe and increase the injection pressure to do the test to ensure that the pipe can withstand sufficient pressure.
After the backfilling process of the pipe trench is completed, the construction materials and debris in the operation zone will be cleaned up and restored according to the pre-construction landforms.
Project completion and acceptance
After the construction phase is completed, the project completion acceptance can be carried out after the successful completion of the commissioning, delivery acceptance and special acceptance processes. This is the last work of engineering project management, the work is a symbol of the formal transfer of the project from construction to operation, but also a comprehensive assessment of investment benefits, test the design and construction quality of an important link.
After a long period of research and exploration, China’s oil and gas pipeline construction technology has made great progress. In the future, the national pipeline network will also rely on scientific and technological innovation and management innovation to vigorously promote the construction of long-distance oil and gas pipelines, promote the sustainable economic and social development of areas along the pipeline, and build a “national network” as soon as possible.
Source: China Steel Pipeline Manufacturer – Yaang Pipe Industry (www.metallicsteel.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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