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Vol.13, No1, 2013, pp.63–74
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QUALITY ASSURANCE OF STORAGE TANKS AFTER IN-SERVICE CRACK REPAIRS Ramo Bakić1, Ljubica Milović2, Radomir Jovičić3, Stojan Sedmak4 1)Tehnička škola, Tutin. Serbia, ramo.bakic@gmail.com 2)University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia 3)University of Belgrade, Faculty of Mechanical Engineering – Innovation Centre, Belgrade, Serbia 4)Society for Structural Integrity and Life (DIVK), Belgrade, Serbia |
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Abstract According to the Pressure Equipment Directive (PED 97/23/EC) a new produced storage tank can be accepted on the market only if the required quality is proved. In this way the structural integrity might be at the requested level. However, it is not possible to apply all rules and standards for the quality during service and after performed repairs that are necessary to sustain the structural integrity of the storage tank. Storage tanks of steel are produced in general as cylindrical or spherical, and individual segments are joined by welding. Welded joints are prone to crack occurrence, and for that they are critical locations for safety and structural integrity. According to standard EN ISO 5817 cracks are not acceptable defects in welded structures, and detected cracks have to be removed. The applicability of quality assurance approach to repaired pressure equipment is analysed and discussed in this paper. In the first case welded joints in spherical storage tanks produced of normalized high strength steel (460 MPa yield stress) microalloyed with vanadium are analysed, considering repair and structural integrity assessment. In the second case, dissimilar welded joints of structural and stainless steel are examined. Keywords: storage tank, cracks in welded joint, heat-affected-zone (HAZ), normalized structural steel, stainless steel, structural integrity assessment |
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full article (587 kB)
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