Thesis Type: Postgraduate
Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2019
Thesis Language: Turkish
Student: MURAT SEZGİN
Supervisor: CEMİL ÇETİNKAYA
Abstract:Energy consumption in the world increases every year with the development of technology and industry. Oil and natural gas are the main sources used to meet the energy needs. Turkey is between the Middle East and Caucasus geography, rich in oil and natural gas, and Europe. Because of its position, Turkey is located in a powerful transmission line. Pipeline transmission in natural gas transfer is increasing day by day. Especially with the projects in recent years, Turkey shows itself in natural gas transfer. Welding methods used in field joining of pipelines are developing with the developing technology. Despite these developments, the scarcity studies on natural gas pipelines in Turkey is remarkable. In this study, the Orbital Welding System used in field joints of API X70 material used in natural gas pipelines was examined considering this deficiency. Root and cover pass welding processes are done by using arc welding method with covered electrode for API X70 quality 56” pipe. Hot and fill pass welds were done by Orbital-MAG Welding Method. The welding was carried out clockwise and counterclockwise from 6 to 12. At the end of the welding process, samples were divided into 4 zones as 12-3, 3-6, 6-9, and 9-12 in order to examine the structure. The heat input of each zone was examined on microstructure images. They were also subjected to destructive tests to examine the mechanical properties of these zones. As a result of these tests, the effect of heat distribution on microstructure and mechanical properties was evaluated. According to the test results obtained from the welded joint, the desired welding capability is achieved