Girth welding process and application of X60/625 nickel-based alloy clad pipe

In girth welding of X60/625 bimetal clad pipe, because of the great differences of the chemical composition and physical properties of the two kinds of materials, it was prone to cause oxidation and dilution of nickel-based alloy layer, thus affecting the corrosion resistance of cladding layer and pipeline integrity. For the problem, the weldability and welding process of the X60/625 bimetal clad pipe were analyzed and studied in this article, so as to develop a girth welding process for X60/625 bimetal clad pipe. After nondestructive test, physical and chemical properties test, corrosion resistance test and dilution rate test of the weld, the results met the relevant standards and specifications. The welding process were successfully applied to first part clad pipeline of Saudi Arabia Halad Project, 612 welded joints were finished and the weld pass rate was 99.7%.Highlights: In order to solve the welding problem of dissimilar metal in the ring weld of X60/625 bimetal composite pipe, welding method of GTAW + SMAW with homogenous welding material was proposed in this paper, and the welding process of 7 layers and 16 passes was adopted. The welding process were successfully applied to first part clad pipeline of Saudi Arabia Halad Project and the weld pass rate was 99.7%.