Analysis Of Pipe Elbows Creep Under Multiaxial Stress State

With the rapid pace of our economy, the demanding of electricity is becoming urgent. As so far, Large numbers of ultra-supercritical plants have been developed. In the following one or two decades, the prevailing plants will be supercritical and ultra-supercritical ones, with the steam temperature and pressure up to600℃and30MPa respectively. The safety of pipes under high temperature and pressure conditions will turn to be more and more essential, especially for inspecting the pipe bends under multi-axial stress states due to elevated temperature creep.This paper aims at fitting the uniaxial stress experiment data of P92steels, with the software ANSYS,applying the creep constitutive equations to the pipe elbows under elevated temperatures conditions. Firstly, the stress distribution and its changes of the pipe elbows, subjected to internal pressure, are analyzed. And then coMPare them with theoretical formulas. During the analysis the creep is involved, analysis of the thickness and skeletal point stress of the pipe elbows are considered. Then, with the effect of the outer load bending moment, discussed the relationship of the45°elbow section stress and the tension, the change of the ovality and thickness. With the constant stress, the creep deformation increases slowly, then it will result in the damage to the pipeline. Finally, after lots of computing, which provide theoretical support for the full-size pipe elbows creep experiment, which will reveal the law of creep damage under the multiaxial stress state.