TYPICAL APPLICATION OF PRIMARY STRUCTURE METHOD IN STRESS ANALYSIS ON SPHERICAL TANKS, TOWERS AND HEAT EXCHANGERS[1] Sang Rubao, Huang Yongli, Liu Hanbao （ SINOPEC Engineering Incorporation, Beijing , 100101） Abstract： Strength analysis of pressure vessel involves static strength, shakedown and fatigue strength.Generally,finite element analysis （FEA） is the most commonly used method for strength analysis.Since the results given by FEA only include the total stress while the primary stress related to the static strength and secondary stress related to the shakedown cannot be given,the corresponding stress evaluation can＇t be made.