High con-centration of chloride ion in processing fluid and poor welding quality ol evaporator were the main causes of evapo-rator failure.

• 而蒸发釜工作介质中较高氯元素的存在是形成应力腐蚀的特定介质条件；焊接工艺不当是造成蒸发釜产生应力腐蚀，并快速失效的主要原固。