Authors : M. Rama, Rr. Maksuti, H. Mehmeti and M. Shala-Mehmeti
Abstract: In recent years, the demand for welded steel pipes of large diameter for oil and gas transmission (pipelines) over long distance was increased rapidly. One of the most economical ways of producing these steel line pipes is Double side Submerged Arc Welding process (DSAW) of previously hot rolled steel coils formed into a round shape by uniformly plastic deformation, having a double side single pass spiral weld entire length of the pipe. In order to continuously production, the tail end of the previous coils and lead of the incoming coils are sheared and welded together on one side single pass in the transverse direction of the coils length and this welded joint is called transverse or scalp end weld. In the absence of the outside weld pass of this weld joint must be completely repaired by Manual Arc Welding process (MAW) and controlled on the purpose to increase the reliability and quality of the welded pipes. The objective of this study is to determine hardness distribution within repaired transverse welded joint in vanadium micro alloyed X65 steel pipes. This is achieved by careful hardness measurements (HV30/15 and metallographic examination of selected specimens, extracted from the repaired transverse welded joints in vanadium micro alloyed X65 steel pipes Ø 812.8x12 mm. Hardness distribution within repaired welded joint has its own hardness range and meet all the standard requirements of API 5L-X65.
M. Rama, Rr. Maksuti, H. Mehmeti and M. Shala-Mehmeti, 2009. Hardness and Microstructural Changes During Repaired Welding of the Pipes of Power Plant Kosova. Journal of Engineering and Applied Sciences, 4: 348-352.