The Analysis Of Welding Cracks Of Low Temperature Separation-condensator Of Natural Gas

This article apply modern methods and means of failure analysis, to explore the low temperature separation condenser explosion accident of the natural gas treatment plant of a oil company. by observation and measurement of the accident site , investigating and understanding of equipment operating conditions and the process of the accident occurred, Sampling debris from the scene, to complete determination of the chemical composition and mechanical properties, microstructure inspection, electro-microscopic scanning of the fracture, X-phase scan, the technical inspection, identification and calculation of vessels explosion energy , to conduct comprehensive failure analysis, to identify the cause of the explosion of the low-temperature separation condenser, to analyze the existing problems in the production process, take effective measures, to provide technical basis for guaranteeing the safe operation of equipment, preventing accidents.That is found in the failure analysis : Cracks in two main sources; First, non-metallic inclusions in the weld gathering, another is Composites / substrate interface cracks, holes and other defects. Microstructure and scanning electron microscopy confirmed: non-metallic in weld inclusions is very serious , this reduced the weld strength and low temperature impact toughness, this conclusion is confirmed by determination of mechanical properties; in the observation ,we also found more cracks, minute holes and melting metal balls in the composites / substrate interface, caused by the high temperature of the explosion welding or a number of heating and cooling of the conjecture composite plate , These deficiencies greatly reduce the bonding strength, as one source of cracks.In this paper, by failure analysis, we eventually find the root cause of the accident: welding defects in the low temperature separation condenser is the main reason of the accident, welding defects caused weld performance to drop, at the same time caused gas leak so the explosion occurred.The process of the accident is : because of the defects in the welds of the low temperature separation condenser, combustible gases leaking the containers ,so, the first explosion occurred after mixing with the air, Thus make the separator ruptured , large amount of air got into the separator, caused the second explosion.The paper discussed the types of weld defects of pressure vessels and it's cause,...