The Study Of The External Pressure Stress Factor B Curve Of Typical Domestic Material

Cylindrical shell under external pressure is widely used in the industry. It is extremely important to ensure container’s safe and reliable.The main failure of external pressure vessel is buckling, so the key to ensure its safety is to ensure its in stability. External pressure factor B curve has played a key role in the external pressure vessel’s stability design.Factor B curve in current Standard GB150is partly from Standard ASME’s, partly from the experament’s curve in1970s.Due to the material’s different between domestic and abroad,and the progress of smelting technology, it is necessary to redeterminate and study some material curves in Standard GB150.This paper reseach the inadequate about external pressure factor B curve in current Standard.(1) Doing tensile test of eight kinds of different materials at normal temperature and high temperature.Select the Ramberg-Osgood model for all curve fitting after compareing various types of fitting model,then obtain the external pressure factor B curve of different materials at different temperatures.(2) Comparing the external pressure factor B curve’s different in test curve, Standard GB150and Standard ASME.It is found that austenitic stainless steel and low carbon steel curve in Standard GB150is diffierent from tests’,but the high-strength steel curve is the same to the test, and then analyzes the causes of the differences..(3)The material divided into three categories which named low-carbon steel, high-strength steel and stainless steel base on the test curve.This paper uses unified external pressure factor B equation to describe each of three categories,and given the external pressure design methods and formulas according to the the unified external pressure factor B. Examples demonstrate the deviation is less when it designed by unified external pressure factor B curve compared to the common method Also proposed a unified curve for most materials, and numerical examples prove that there is a certain error calculate the results compared with the traditional uniform curve, but within the acceptable range.(4)It is account that the stability safety factor in GB150is quitely conservative after comparing the diffenent stability safety factor in each countries’s standard.This paper obtain a new variable coefficients external pressure factor B curve which reflect safety factor on the basis of test curve,and make the safety factor closer to which in ASME VIII-2. Examples demonstrate the external pressure allowable stress caculated by variable coefficients external pressure factor B is higher than that caculated by the method in GB150,the design level is equal to the ASME VIII-2and EN13445.