Strength Anaysis And Reliability Research Of Giant Steel Sphere

The steel sphere is one of important pressure stocking devices in the petroleum and chemical industry. It's used to contain combustible and explosive medium. In case the giant sphere cracks while it is working, accidents will be occurred.This paper calculate force and stress of sphere during usage at different liquid levels though finite elements method, analyze making material and welding material affection on strength 0By researching the corrosion ferture and theory, look for the reasons of cracks occurred on the sphere. Find the reason is resulted from sub-sulphide hydrogen stress corrosion according to characteristics of cracks detected on site, furthermore electron microscope analysis, metallographic examination, component test and hardness test. The most sensitive cracks of sub-sulphide hydrogen stress corrosion only occurred under 90 'C,usually,around 20桽O'C.Above 90"C,it is just a common sulphide hydrogen corrosion, sub-sulphide hydrogen stress corrosion cracks occurred on heating influded area.We also find the sensitability of sub-sulphide hydrogen stress corrosion cracks has closely related with component, metallographic strenghth and hardness.Obtain reasonable measures preventing cracks and repairing test through study theory, conditions and rules of sub-sulphide hydrogen stress corrosion enlarging. Decrease the percentage of sulphide hydrogen; Remove hydrogen from shell bady and recover materal mechanical performance; Dispel sulphide hydrogen stress corrosion cracks, hydrogen bubbles and other defacts by by means of soften organization mending weld; Improve welding line performance and drop down hardness and anti-corrosion ability; Slack and eliminate reminded strees, especially, welding reminded strees; resist hydrogen adsorption and penetration on the inner surface of shell by coating layer.demonstrale that the giant steel shere cracks filling with lighter hydrocarbon can be repaired very well by means of soften organization mending weld and heating treat experiments after welding.