The gas pipelines perform various tasks in the distribution sector, including the transfer of gas from the transmission sector to the pressure-reducing stations, the transfer of gas from the stations to each other, and the transfer of gas from the stations to the stations of consumption. In general, gas pipelines in the distribution sector are divided into two types of supply pipelines and distribution network pipelines. The supply pipelines are responsible for the transmission of gas from downstream stations to the cities, while the distribution of natural gas in the urban pipeline network is the responsibility of the distribution pipelines. Pipelines can be categorized in several other respects. Pipelines are divided into two types of underground gas pipelines and ground gas pipelines from the point of view of location. Also in terms of pipe type can be mentioned types of protected or unprotected steel, cast iron, iron, polyethylene and copper. Depending on the design, capacity, environmental characteristics, soil characteristics and other influencing parameters of each of the following types of pipes can be used.
National Iranian Gas Company supplies its used gas pipe from several suppliers. On the other hand, the information printed on the pipes by the common methods during the storage of these pipes in the open warehouses due to the rusting of the pipe wall and also in the final stage of preparation of the pipes for the execution of the gas pipeline during the coating workshop. The shotgun process will be eliminated. Then, after running the pipeline and any other accident or problem, no pipe identification is available and it is virtually impossible to determine the pipe manufacturer.
Implementation of gas and oil pipelines
The gas and oil pipelines are the main and vital arteries of the countries. As the tenders of the transmission lines grow and the projects are transformed from domestic to international projects of the National Iranian Gas Company, it has to supply its required pipes from numerous sources and factories simultaneously. A major challenge is to track the pipes and their resources after the production phase until the pipelines are implemented.
Implementation of gas transmission lines requires high levels of safety and hence all pipes go through several stations for quality control and inspection to meet the requirements of relevant standards, from the beginning of the process to the installation site.
The process of producing a longitudinal welded gas pipe
The raw materials for pipe making are hot and cold rolled sheets that are purchased as coils from steel companies. The coils are divided into smaller parts, called coils or strips, according to the order and need of manufacture. Splitting the coil into the coil is done by the cutting machine. After the coil is cut and turned into a coil, the coils are transferred to the rolling section.
To produce a longitudinal seam pipe, the sheet used must have the following properties
Have high weldability
The defects of climbing and separation in steel should be minimal
The surface of the sheet is smooth and the oxide shells on the outer surface of the sheet are not high.
Curvature along the sheet should be minimal
Do not have sheets of internal tension.
Characteristics of sheet used for gas pipe production
The steel sheets used must have a specific chemical composition as they affect the mechanical properties, microstructure, grain size and weldability. Commercial steel is usually used to produce steel welded pipes or pipes that later become profiled. The methods of pipe manufacturing are divided into two general categories, including seamless methods and methods of pipe welding. The methods of producing the seam tube use a heated work sheet, or a cold sheet. The sheet should be shaped into a tube and welded to the seam.
One of the methods of sheet forming is the O&U method. In this method, the molds are first converted to U and then to O. Sheet molding is done in cold mode. Before forming, the edges of the sheet are bent and welded directly after forming