Weldability of pipes produced for crude oil and natural gas pipelines with the method of submerged and spiral arc welding and researching their mechanical properties

WELDABILITY OF PIPES PRODUCED FOR CRUDE OIL AND NATURALGAS PIPELINES WITH THE METHOD OF SUBMERGED AND SPIRALARC WELDING AND RESEARCHING THEIR MECHANICALPROPERTIES(M.Sc. Thesis)Hakan ADAGAZİ UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYOctober 2006ABSTRACTSpiral pipes made of steel with the method of submerged arc welding are usedquite extensively in the transmission line of crude oil and natural gas. However,especially under high pressures, the need for the quality in the performance ofcrude oil and natural gas pipelines is getting more and more significant. Thekind of the steel material used, the wall thickness of the material, chemicalcomposition of welding metal and its mechanical properties, the kind ofwelding wire and powder, the amount of additional welding metal, the speedand the parameters of the welding are the leading factors affecting theperformance of the crude oil and natural gas pipeline. All of these factorsemphasize the importance of the study on welding design.In this study, primarily a fully comprehensive research on the production ofspiral pipe with the method of submerged arc welding has been done. What isaimed at in the experimental studies is the examiantion of the mechanicalperformance of the pipes produced for the crude oil and natural gas pipelineswith the method of submerged arc welding and spiral pipe using differentmaterials and effects of welded composition on microstructures and mechanicalproperties in addition to the comparison of materials used. In the experimentalstudies, X65, X52, X70, X60 natural gas pipeline in the standard of API 5L andX65 crude oil pipes in different sizes have been composed by welding andchemical analysis, hardness, tensile strength, charpy impact, bending tests havebeen made. Besides, macro and micro photographs of these weldedcompositions have been taken. As a result of experiments performed, the mostproductive mechanic test results among the materials used are obtained fromnatural gas pipe which is manufactured from X70 material.Science Code : 710.3.019Key Words : Submerged arc weldingPage Number : 157Adviser : Prof. Dr. Cemil ÇETİNKAYA